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Showing 1 - 200 of 3162 Journals sorted alphabetically
A Practical Logic of Cognitive Systems     Full-text available via subscription   (Followers: 9)
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 33, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 23, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 95, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 25, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 36, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 5)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 7)
Acta Astronautica     Hybrid Journal   (Followers: 412, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 27, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 2)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 10, SJR: 0.18, CiteScore: 1)
Acta Haematologica Polonica     Free   (Followers: 1, SJR: 0.128, CiteScore: 0)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 249, SJR: 3.263, CiteScore: 6)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.504, CiteScore: 1)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.542, CiteScore: 1)
Acta Oecologica     Hybrid Journal   (Followers: 12, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 1, SJR: 1.793, CiteScore: 6)
Acta Poética     Open Access   (Followers: 4, SJR: 0.101, CiteScore: 0)
Acta Psychologica     Hybrid Journal   (Followers: 27, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access   (Followers: 1)
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 6, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 6)
Acute Pain     Full-text available via subscription   (Followers: 14, SJR: 2.671, CiteScore: 5)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.53, CiteScore: 4)
Addictive Behaviors     Hybrid Journal   (Followers: 16, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 8, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 9, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 148, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 8, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 12, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 28, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 10, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 11, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 23, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 14, SJR: 0.572, CiteScore: 2)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.61, CiteScore: 7)
Advances in Botanical Research     Full-text available via subscription   (Followers: 2, SJR: 0.686, CiteScore: 2)
Advances in Cancer Research     Full-text available via subscription   (Followers: 32, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 8, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 3)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 27, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.713, CiteScore: 1)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 10, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 29, SJR: 1.562, CiteScore: 3)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19, SJR: 1.977, CiteScore: 8)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.205, CiteScore: 1)
Advances in Dermatology     Full-text available via subscription   (Followers: 15)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 12)
Advances in Digestive Medicine     Open Access   (Followers: 9)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 25)
Advances in Ecological Research     Full-text available via subscription   (Followers: 44, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 28, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 44, SJR: 5.39, CiteScore: 8)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 58, SJR: 0.591, CiteScore: 2)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Genetics     Full-text available via subscription   (Followers: 16, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 8, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 12, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 36, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Marine Biology     Full-text available via subscription   (Followers: 17, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 11, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 22)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 3)
Advances in Oncobiology     Full-text available via subscription   (Followers: 1)
Advances in Organ Biology     Full-text available via subscription   (Followers: 1)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 17, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.174, CiteScore: 0)
Advances in Parasitology     Full-text available via subscription   (Followers: 5, SJR: 1.579, CiteScore: 4)
Advances in Pediatrics     Full-text available via subscription   (Followers: 24, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 11)
Advances in Pharmacology     Full-text available via subscription   (Followers: 16, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.574, CiteScore: 1)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.109, CiteScore: 1)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 9)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 62)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (Followers: 1, SJR: 0.263, CiteScore: 1)
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.101, CiteScore: 0)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 6)
Advances in Space Research     Full-text available via subscription   (Followers: 395, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
Advances in Surgery     Full-text available via subscription   (Followers: 10, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 33, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 17)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 46, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 342, SJR: 0.796, CiteScore: 3)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.42, CiteScore: 2)
African J. of Emergency Medicine     Open Access   (Followers: 6, SJR: 0.296, CiteScore: 0)
Ageing Research Reviews     Hybrid Journal   (Followers: 11, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 449, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 17, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 31, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 42, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 3)
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 57, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 6, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 11, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 9)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 11, SJR: 1.142, CiteScore: 4)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.504, CiteScore: 1)
Allergology Intl.     Open Access   (Followers: 5, SJR: 1.148, CiteScore: 2)
Alpha Omegan     Full-text available via subscription   (SJR: 3.521, CiteScore: 6)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 9, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 52, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 4, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 4, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 6)
American Heart J.     Hybrid Journal   (Followers: 50, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 54, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 45, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 10)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 34, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 28, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 35, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 46)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3, SJR: 1.967, CiteScore: 2)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 209, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 63, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5, SJR: 0.265, CiteScore: 0)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.289, CiteScore: 1)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, CiteScore: 1)
American J. of Pathology     Hybrid Journal   (Followers: 28, SJR: 2.139, CiteScore: 4)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 28, SJR: 2.164, CiteScore: 4)
American J. of Surgery     Hybrid Journal   (Followers: 38, SJR: 1.141, CiteScore: 2)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.767, CiteScore: 1)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 7)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 62, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 17, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 3, SJR: 0.277, CiteScore: 0)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription  
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 5, SJR: 4.849, CiteScore: 10)
Analytica Chimica Acta     Hybrid Journal   (Followers: 43, SJR: 1.512, CiteScore: 5)
Analytical Biochemistry     Hybrid Journal   (Followers: 175, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 11, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 11)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 23, SJR: 0.683, CiteScore: 2)
Angiología     Full-text available via subscription   (SJR: 0.121, CiteScore: 0)
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1, SJR: 0.111, CiteScore: 0)
Animal Behaviour     Hybrid Journal   (Followers: 194, SJR: 1.58, CiteScore: 3)

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Journal Cover
Analytica Chimica Acta
Journal Prestige (SJR): 1.512
Citation Impact (citeScore): 5
Number of Followers: 43  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0003-2670 - ISSN (Online) 1873-4324
Published by Elsevier Homepage  [3162 journals]
  • Ultrasensitive detection of glutathione based on liquid crystals in the
           presence of γ-glutamyl transpeptidase
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Lele Zhou, Qi Kang, Oiongzheng Hu, Li Yu Glutathione (GSH) is of significance in human pathology due to its many cellular functions. γ-Glutamyl transpeptidase (γ-GT) plays a key role in the balance of GSH by breaking down extracellular GSH. In this study, we proposed a novel strategy for sensitive and selective detection of GSH based on LC sensing platform coupled with its inhibition of γ-GT. The γ-GT cleavable surfactant, dodecyl N-ethanamide N, N, N-trimethylammonium bromide (DAA), was synthesized and utilized to decorate the aqueous/LC interface. A black optical image of LCs was observed due to formation of the self-assembled DAA monolayer at the interface. Subsequently, the optical response of LCs returned to bright appearance after transferring γ-GT to the DAA-laden interface because DAA could be enzymatically hydrolyzed by γ-GT and the monolayer was disrupted. Interestingly, LCs remained dark images after the DAA-decorated interface in contact with the pre-incubated GSH and γ-GT. The detection limit of GSH reached 1 pg/mL, which demonstrates high competitiveness with the current assays. The detection mechanism of GSH was explained by Isothermal titration calorimetry (ITC) measurements and Fourier transform infrared (FTIR) spectroscopy. This work presents an appealing route to achieve ultrasensitive detection of GSH according to its hydrolysis by γ-GT and the as-prepared simple and robust LC-based sensing platform has potentials in the diagnosis of GSH-related diseases (e.g. cancer, liver damage, and malignant neoplasms).Graphical abstractImage 1
  • Colorimetric sensor for the detection of H2S and its application in
           molecular half-subtractor
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Rahul Kaushik, Amrita Ghosh, Ajeet Singh, D. Amilan Jose Azine based new colorimetric sensor 1 for the detection of gasotransmitter H2S has been reported. Sensor 1 used to detect the H2S with a remarkable red shift of 105 nm in the absorption spectra with a colour change from light yellow to brown red. Importantly, rare example of azine derivative has been used as a colorimetric probe for H2S detection using deprotonation mechanism. H2S induced deprotonation of one of the -OH proton followed by a change in resonance of 1 is responsible for the ratiometric spectral and colour change. The detection response was quick and the LOD calculated as 18.2 μM. Sensor 1 was also explored in the detection of H2S in biological fluids such as human serum and mouse serum. Moreover, for the first time, we have shown the applicability of H2S for the construction of half subtractor molecular logic gate.Graphical abstractColorimetric sensor 1 for the detection of H2S via deprotonation mechanism has been reported. The response was fast and the LOD calculated as 18.2 μM. Sensor 1 is applicable to determine H2S level in biological fluid like mouse/human serum and also to construct a molecular logic function half-subtractor.Image 1
  • Detection of nitrite with a surface-enhanced Raman scattering sensor based
           on silver nanopyramid array
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Peng Zheng, Sujan Kasani, Xiaofei Shi, Ashley E. Boryczka, Feng Yang, Haibin Tang, Ming Li, Wanhong Zheng, Daniel E. Elswick, Nianqiang Wu Nutrient pollution is of worldwide environmental and health concerns due to extensive use of nitrogen fertilizers and release of livestock waste, which induces nitrite compounds in aquatic systems. Herein a surface-enhanced Raman scattering (SERS) sensor is developed for nitrite detection based on coupling between the plasmonic gold nanostars and the silver nanopyramid array. When nitrite is present in the assay, an azo group is formed between the 1-naphthylamine-functionalized silver nanopyramids and the 4-aminothiophenol-functionalized gold nanostars. This not only generates the SERS spectral fingerprint for selective detection, but also creates “hot spots” at the gap between the Au nanostars and the Ag nanopyramids where the azo group is located, amplifying SERS signals remarkably. Finite-difference time-domain (FDTD) simulation shows a SERS enhancement factor of 4 × 1010 at the “hot spots”. As a result, the SERS sensor achieves a limit of detection of 0.6 pg/mL toward nitrite in water, and enables nitrite detection in real-world river water samples. In addition, this sensor eliminates the use of any Raman reporter and any expensive molecular recognition probe such as antibody and aptamer. This highly sensitive, selective and inexpensive SERS sensor has unique advantages over colorimetric, electrochemical and fluorescent devices for small molecule detection.Graphical abstractImage 1
  • Highly sensitive electrochemical immunosensor for golgi protein 73 based
           on proximity ligation assay and enzyme-powered recycling amplification
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Ying Zhang, Xiaocui Huang, Fang Luo, Yun Lei, Li Chen, Zuquan Weng, Longhua Guo, Zhenyu Lin Golgi protein 73 (GP73) is a potential hepatocellular carcinoma serum marker with better sensitivity and specificity. In this study, a highly sensitive electrochemical immunosensor which combines the highly selective proximity ligation assay (PLA) and highly efficient enzyme-powered recycling amplification has been developed for GP73 determination. PLA is triggered by affinity binding of two labelled antibody-DNA (P1-RAb and P2-MAb) to target protein, resulting in increased specificity. The formed immunocomplex hybrids with DNA2 to realize the release of methylene blue labelled mononucleotides fragment with the help of exonuclease III, which acts as the power of recycling amplification. The fragment can diffuse easily to the nafion modified indium tin oxide electrode surface and a strong electrochemical signal can be detected. Under the optimized conditions, the enhanced electrochemical intensity has a linear relationship with the concentration of GP73 in the range of 0.3 pg mL−1 to 6.0 ng mL−1 with the detection limit of 0.10 pg mL−1. The developed immunosensor has been applied to detect the GP73 in the clinical serum samples with satisfactory results.Graphical abstractImage 1
  • Highly luminescent green-emitting Au nanocluster-based multiplex lateral
           flow immunoassay for ultrasensitive detection of clenbuterol and
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Tao Peng, Jianyi Wang, Sijun Zhao, Yuyang Zeng, Pimiao Zheng, Demei Liang, Ghulam Mujtaba Mari, Haiyang Jiang A multiplex lateral flow immunoassay sensor based on highly luminescent green-emitting Au nanoclusters (AuNCs-MLFIA sensor) was successfully established for the simultaneous and quantitative determination of clenbuterol (Clen) and ractopamine (RAC) in swine urine. The antigens of Clen and RAC were dispersed on a nitrocellulose membrane as two test lines, and the Au nanoclusters were synthesized from 6-aza-2-thiothymine and l-arginine to obtain highly green luminescence and ultra-small nanoparticles (Arg/ATT/AuNCs). Free carboxyl groups on Arg/ATT/AuNCs enabled conjugation with biomolecules to afford an indicator for the biosensor. The AuNCs-MLFIA sensor is based on the indirect competition assay and could successfully detect samples within 18 min without sample pretreatment, qualitative results can be obtained by visual inspection under a UV lamp. The limits of detection of Clen and RAC by the naked eye were both 0.25 μg L−1. In addition, the AuNCs-MLFIA sensor allowed quantitative detection combined with a portable fluorescence reader. The half-maximal inhibitory concentrations of Clen and RAC were 0.06 and 0.32 μg L−1, respectively, with detection limits of 0.003 and 0.023 μg L−1. Thirty blind-spiked swine urine samples were analyzed by the AuNCs-MLFIA sensor and liquid chromatography–tandem mass spectrometry, and the results of the two methods showed a significant correlation. The newly developed AuNCs-MLFIA sensor overcomes several limitations of conventional LFIA sensors, including their low sensitivity, limitation to quantify analytes, and single-analyte detection.Graphical abstractMultiplex LFIA sensor based on highly luminescent green-emitting gold nanoclusters for simultaneous and quantitative determination of Clen and RAC in swine urine.Image 1
  • Cu-Mn codoped ZnS quantum dots-based ratiometric fluorescent sensor for
           folic acid
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Yongbo Wang, Min Yang, Yingkun Ren, Jun Fan In the design of new fluorescent sensors, exploration of new materials with excellent properties and smart designs is of continuing interest. Herein, we designed a dual-emission ratiometric fluorescent sensor by doping ZnS quantum dots (QDs) with Cu2+ and Mn2+ ions. The codoped ZnS QDs with two separated dopant emissions were used as ratiometric fluorescent sensors for folic acid (FA). With addition of FA, the Cu dopant emission was quenched while the Mn dopant emission was enhanced. The fluorescence intensity ratios versus the FA concentrations could be fitted to a linear regression equation ranging from 0.01 to 5 μM (R2 = 0.995) and the detection limit was calculated to be 6 nM. Thus, this method generated ratiometric fluorescence signals for quantitative detection of FA. To understand the specific fluorescence response of the sensors for FA, the sensing mechanism was proposed based on electron transfer between QDs and FA. Additionally, the sensors were successfully applied to the determination of FA in spiked samples and recoveries were ranged from 95.5 to 102.2%. Therefore, the sensors show high sensitivity and selectivity for FA and the proposed method has good potential for extension to the detection of other biological molecules after further development.Graphical abstractImage 1
  • Experimental development of a biosensor system to measure the
           concentration of phenol diluted in water using alternative sources of
           oxidoreductase enzymes
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Gilmar Tuta-Navajas, Katherin Gutierrez-Avila, Sebastian Roa-Prada, Graciela Chalela-Alvarez The presence of phenol in industrial wastewater is an issue of great relevance for petrochemical and energy companies, among others. The high toxicity level of this substance requires polluting industries to continuously monitor the concentration of phenol in their wastewaters so as to comply with environmental regulations and to minimize environmental impact. This research work proposes the experimental development of an analytical method for “in situ” measurement of the concentration of phenol diluted in water, with application in Oil & Gas production wastewater monitoring. The method is based on the principle of selectivity exhibited by the oxidoreductase enzymes in the presence of phenolic compounds. The differences in the performance found when using organic tissues and microorganisms, as natural alternative sources of the enzyme, are also highlighted. These alternative sources of oxidoreductase enzyme work as the recognition element of the biosensor. A dissolved oxygen sensor is used as the transducer of the chemical signal produced by the reaction between the analyte and the enzyme. The bioencapsulation technique is very adequate in this case, because it offers a nutrient medium to the microorganisms and is reusable, making it ideal for repetitive measurement applications. The results show that the biosensor exhibits an approximately linear behavior when measuring phenol concentrations from 0.2 to 2 ppm.Graphical abstractImage 1
  • A facile plasmonic silver needle for fluorescence-enhanced detection of
           tumor markers
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Naseer Ullah Khan, Zhenzhen Feng, Hua He, Qian Wang, Xu Liu, Shan Li, Xinjian Shi, Xiaojuan Wang, Baosheng Ge, Fang Huang Tumor markers have been regularly detected for early cancer diagnosis in clinical oncology. The development of facile and low cost technology has become an important challenge for their diagnosis. We here report a low-cost plasmonic silver needle (PSN) for immunofluorescence detection of tumor biomarkers. The fluorescence signal is enhanced on the needle by up to 220-fold, allowing high-performance detection of tumor markers down to 0.08 ng mL-1. To assess the clinical potential of the proposed assay technique, PSN-based sandwich immunoassay for the detection of alpha-fetoprotein and carcinoembryonic antigen were performed for blood as well as for serum sample. The results from serum sample have an excellent agreement with an electrochemluminecence assay. The small relative error and a good linear correlation suggest that the accuracy and precision of this analytical technology are satisfactory. This assay technique with lower cost, use of less sample, higher sensitivity and easier procedure shows great promise for the facile and early cancer diagnosis.Graphical abstractImage 1
  • Integrated multichannel all-fiber optofluidic biosensing platform for
           sensitive and simultaneous detection of trace analytes
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Wei Li, Haoyu Wang, Rong Yang, Dan Song, Feng Long, Anna Zhu An integrated multichannel all-fiber optofluidic biosensing platform (M-AOB) has been developed for a sensitive, rapid, and simultaneous detection of up to three trace analytes. The M-AOB platform employs a 1 × 3 fiber optical switch and three single-multimode fiber optic couplers for the transmission of excitation light and fluorescence and one photodiode detector for the simultaneous detection of fluorescence signals of multiple channels based on the time-resolve effect of the fiber optical switch. This design greatly simplified the entire system structure and improved light transmission efficiency. Through an indirect competitive immunoassay mechanism, we detected two highly regulated small molecules, namely, atrazine and 2,4-D, to demonstrate the value of M-AOB to the simultaneous measurement of trace analytes in water samples. The limits of detection of 0.03 μg/L and 0.04 μg/L were obtained for atrazine and 2,4-D, respectively, and were highly comparable with those of other analytical techniques. The high sensitivity of M-AOB benefited from the high light collective efficiency and low light loss of the excellent all-fiber optical structures and from the advantages of the evanescent wave technique. The regeneration of the biosensor surface, 200 assay cycles, were performed without any significant activity loss. Each assay cycle was less than 15 min. The immunoassay performance of the M-AOB, evaluated in several spiked water samples, showed good recovery, accuracy, and precision, indicating that the M-AOB was less susceptible to matrix effects of water samples. All these results illustrated that M-AOB can be readily extended toward the simultaneous and rapid detection of other trace small molecules using different biosensors modified by other analyte conjugates and their respective fluorescence-labeled antibodies.Graphical abstractImage 1
  • A fast and visual method for duplex shrimp pathogens detection with high
           specificity using rapid PCR and molecular beacon
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Cheng Qian, Rui Wang, Cui Wu, Liu Wang, Zunzhong Ye, Jian Wu, Feng Ji Molecular diagnosis of genome is one of the major methods for pathogens detection. The commonly used PCR method can realize an exponential amplification of the target gene but is time-consuming. In this work, we proposed a duplex and visual method using rapid PCR combined with molecular beacons to specifically detect two kinds of shrimp pathogens in one reaction tube. We only need to observe the fluorescence change of the reaction tube with naked eye to determine the result. A home-made automatic transfer equipment allows reaction tubes shuttling quickly between two water baths to achieve rapid PCR amplification. A simple device was also designed to present the detection results easily determined with naked eye. This duplex and visual detection method is fast, low-cost and of high specificity. From DNA extraction to results judgment, only 15 min was enough. Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) and Vibrio parahaemolyticus (VP) are two common shrimp pathogens which were chosen as our detection objects. This method may give a possibility to conduct end-point visual duplex detection, which may make a positive influence on the pathogen prevention.Graphical abstractImage 1
  • Imprinted proteins as a receptor for detection of zearalenone
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Pavel Pidenko, Huiyan Zhang, Pieterjan Lenain, Irina Goryacheva, Sarah De Saeger, Natalia Beloglazova A strategy to design an immunoassay based on imprinted proteins to detect a foodborne toxin zearalenone (ZEN) has been proposed. Proteins were used as scaffolds for generation of binding cavities with a high specificity against ZEN. Different proteins and different bioimprinting approaches were tested. The imprinted proteins primarily prepared in a tube and then immobilized on a microwell plate, and directly prepared in the microwell plate were compared for an application in immunosorbent detection of ZEN in naturally contaminated wheat and maize samples. The assay was combined with a rapid extraction technique. Specific interactions between the imprinted proteins and the target in a μg kg−1 linear range was achieved. As a confirmatory method, liquid chromatography coupled to tandem mass spectrometry was used. The obtained results allow using the developed immunoassay for the analysis of ZEN with a sensitivity matching the maximum permitted level for ZEN in unprocessed cereals established by the European Commission (100 μg kg−1).Graphical abstractImage 1
  • Surface plasmon resonance biosensor for the accurate and sensitive
           quantification of O-GlcNAc based on cleavage by
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Li Gao, Ruihuan Zhao, Yiwen Wang, Mei Lu, Dingding Yang, Mengmei Fa, Xin Yao Abnormal O-linked-N-acetylglucosamine (O-GlcNAc) concentrations have been associated with a variety of diseases (e.g., cancer, Alzheimer's disease, cardiovascular disease, etc.). However, O-GlcNAc detection is complicated, time-consuming and has poor specificity, therefore, the accurate detection of O-GlcNAc is difficult. In this study, an accurate and sensitive surface plasmon resonance (SPR) biosensor for O-GlcNAc detection that is based on β-D-N-acetylglucosaminidase (OGA) and Au nanoparticles (AuNPs) was developed. In this strategy, AuNPs were used to amplify the SPR signal and improve the biosensor's sensitivity; OGA was used to cleave O-GlcNAc from O-GlcNAcylated biomolecules. The interaction between AuNPs labeled wheat germ agglutinin (AuNPs/WGA) and O-GlcNAcylated biomolecules on a modified Au film treated with and without OGA was recorded by SPR. The change of the SPR signal moves linearly with the amount of O-GlcNAc on the Au film and thus could be used for the detection of O-GlcNAc. By recording the difference of the SPR signals, this method can avoid disturbances from other sugars and nonspecific adsorption of AuNPs and thus enable the accurate detection of O-GlcNAc. The accurate detection range of O-GlcNAc was 4.65 × 10−12 to 4.65 × 10−7 M which was obtained by quantifying the amount of a standard O-GlcNAcylated peptide (O-GlcNAc-CREB), and the detection limit is 4.65 × 10−13 M. More importantly, the strategy was successfully used to detect O-GlcNAc in a real α-crystallin protein, cancer cell lysates and blood samples with satisfactory results. The study's results imply that this accurate and sensitive method has the potential to be applied in the early clinical diagnosis of O-GlcNAc-related diseases.Graphical abstractThe principle of accurately detect O-GlcNAc by OGA specific cleavage effect on O-GlcNAc.Image 1
  • Development of a self-priming PDMS/paper hybrid microfluidic chip using
           mixed-dye-loaded loop-mediated isothermal amplification assay for
           multiplex foodborne pathogens detection
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Bo Pang, Kaiyue Fu, Yushen Liu, Xiong Ding, Jiumei Hu, Wenshuai Wu, Kun Xu, Xiuling Song, Juan Wang, Ying Mu, Chao Zhao, Juan Li Foodborne pathogen is the primary cause of foodborne disease outbreak. Given its great damage, a sensitive, simple and rapid detection method is demanded. Herein, we described a self-priming polydimethylsiloxane (PDMS)/paper hybrid microfluidic chip, termed SPH chip, with mixed-dye-loaded loop-mediated isothermal amplification (LAMP) for multiplex foodborne pathogens detection. Staphylococcus aureus (SA) and Vibrio parahaemolyticus (VP) were chosen to verify the novel method. Compared to other similar detection devices, the SPH chip required easier fabrication process, less operation steps and lower cost. Additionally, the reaction result, especially for the weak-positive reaction, could be judged more accurately and conveniently due to the use of mixed-dye. Without pre-enrichment of bacteria in the food contaminated sample, the limit of detection (LOD) reached down to 1000 CFU mL−1 with high specific. Additionally, for fully exploiting the potential of SPH chip, a conceptual eight-channel detection chip was also developed. Overall, the reliable and excellent result demonstrated that the novel method had great potential to be applied in the wider range of pathogens detection or disease diagnose, especially in some resource-limited area.Graphical abstractImage 1
  • A cotton thread fluidic device with a wall-jet pencil-drawn paper based
           dual electrode detector
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Nicolò Dossi, Rosanna Toniolo, Fabio Terzi, Nicola Sdrigotti, Franco Tubaro, Gino Bontempelli A simple and sensitive device is presented based on the use of pencil-drawn paper based electrochemical detector placed at the end of a cotton thread fluidic channel in wall-jet configuration. This innovative and fast responding electroanalytical system can be adopted for both single and dual electrode electrochemical detection, this last achieved by applying two different potentials at two independent working electrodes drawn on the opposite faces of the paper based detector. Its performance was preliminarily optimized by adopting hexacyanoferrate(II) as probe species undergoing reversible electrochemical processes. These devices were then used for the single electrode detection of ascorbic acid in aqueous samples and the dual electrode detection of orthodiphenols in extra virgin olive oils (EVOOs). In fact, these devices enable hydrophilic orthodiphenols, typically present in EVOOs (extracted by a 80:20% v/v acetonitrile/water mixture), to be discriminated from hydrophilic monophenols instead present in almost all vegetable oils. Flow-injections runs were conducted by using a 0.01 M H2SO4 + 0.5 KCl running electrolyte allowing the rapid and selective detection of hydrophilic orthodiphenols with satisfactory sensitivity and a low enough detection limit (2 μM). Different real samples of EVOOs and sunflower oils were analyzed. Abundant enough contents of orthidiphenols were found in EVOO samples, while no trace of these antioxidants was found in sunflower oils.Graphical abstractImage 1
  • One-step DNA purification and amplification on an integrated plastic
           microdevice for on-site identification of foodborne pathogens
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Kieu The Loan Trinh, Yu Zhang, Nae Yoon Lee In this study, we demonstrate a simple and facile method to enable DNA purification and amplification in a continuous step inside a thermoplastic microdevice. The innate property of thermoplastics was adopted to simplify DNA purification because negatively charged DNA can electrostatically interact with the induced positively charged surfaces of thermoplastics as a sample flows inside a microchannel; thus, the DNA purification step can be eliminated. We report the use of natural plastics for the selective adsorption of DNA and conduct a subsequent flow-through polymerase chain reaction (PCR) using a thermoplastic microdevice. Four thermoplastics—poly(methyl methacrylate) (PMMA), polycarbonates (PC), polystyrene (PS), and polypropylene (PP)—were selected as analytical models, and DNA adsorption phenomena on their pristine surfaces were examined. DNA was successfully immobilized onto the pristine thermoplastic surfaces, and the results were confirmed by fluorescent measurement and contact angle measurement and by performing PCR using a thermocycler. The electrostatically attached DNA was subsequently released from the pristine thermoplastic surface using a PCR reagent, which contained a low ionic strength salt as a component that could be used for DNA elution. The eluted DNA was then seamlessly amplified in the subsequent microchannel designed to perform flow-through PCR. The PCR products were collected by a microchamber connected at the end of the microchannel for on-site fluorescence detection. The PMMA microdevice was used to successfully purify and amplify a 210 bp target amplicon from a foodborne pathogen, Escherichia coli O157:H7, within 35 min. This study is expected to pave the way for developing an integrated monolithic thermoplastic microdevice suitable for rapidly identifying foodborne pathogens with reduced operation, decreased manufacturing cost, and enhanced device disposability.Graphical abstractWe fabricate a fully integrated monolithic PMMA microdevice and demonstrate DNA purification, amplification, and on-site detection of major foodborne pathogens in one continuous flow.Image 1
  • Optimization and validation of a fast digestion method for the
           determination of major and trace elements in breast milk by ICP-MS
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Maria Luisa Astolfi, Elisabetta Marconi, Carmela Protano, Matteo Vitali, Elisa Schiavi, Paola Mastromarino, Silvia Canepari Breast milk guarantees all the nutrients required by infants during their first few months of life and remains the most important food source for their health and growth. However, the mother may transfer potentially toxic chemicals to the suckling infant through breastfeeding. The aim of this study was to optimize and validate a fast method for the determination of a total content of 34 elements (Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sb, Se, Si, Sn, Sr, Te, Ti, Tl, U, V, and Zn) in liquid and lyophilized breast milk. The samples were subjected to HNO3:H2O2 (2:1) digestion in an open vessel heated in a water bath (WBD; 80 °C) and subsequently analysed by quadrupole inductively coupled plasma mass spectrometry equipped with a collision-reaction interface.The performance of the proposed method was evaluated in terms of selectivity, detection and quantification limits, linearity, accuracy, and robustness by using standard reference materials and filed samples of breast milk. Compared to microwave-assisted acid digestion, the proposed open vessel digestion allows a significant reduction in treatment time and sample manipulation, while maintaining a similar analytical performance. Masses of 0.5 g of breast milk were efficiently digested with the WBD treatment allowing a residual carbon content lower than 60 mg L−1 and a residual acidity lower than 0.87 mol L−1 in final digested samples. Thus, it shows great potential for application to routine analysis. The method provides satisfactory detection limits and good performance (trueness and recovery percentages 80–111%; coefficient of variation
  • Mixed Vapor Generation Device for delivery of homemade explosives vapor
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Lauryn E. DeGreeff, Christopher J. Katilie, Michael Malito, Braden Giordano While there is a large body of research on the properties and detection of traditional military high explosives and propellant low explosives, there is a dearth of research on homemade explosive (HME) materials, though they are prevalent today. The safety of working with these materials in the laboratory is the greatest limiting factor preventing HME research. A vapor delivery tool, the Mixed Vapor Generation Device (MV-Gen), was designed to safely contain the individual solid or liquid components that often compose homemade explosives vapor plumes and deliver the mixed component vapors for instrumental sampling and analysis. Within the MV-Gen, each component is separated and only the vapors mix as they are carried through the device by flowing air. The resulting mixed vapor is representative of either mixed explosive material or bulk explosives. Component materials are held in up to four individual, removable vials with vapor concentrations controlled by vial orifice size, temperature, and diluent airflow. The total concentration can be adjusted by altering vial temperature via a thermal water jacket surrounding the entirety of the device, or by adjusting the flow rate of diluent air through the device. The MV-Gen was evaluated first with surrogate compounds, followed by two types of homemade explosives, to include a binary explosive mixture and a peroxide explosive. To evaluate the device, vapors were cold-trapped on an online sampling system and analyzed by gas chromatography/mass spectrometry. It was determined that the device yielded reproducible vapor concentrations of both single and mixed components, and the ratio of these vapors can be easily adjusted to mimic varying forms of homemade explosives.Graphical abstractImage 1
  • Hollow-fiber renewal liquid membrane extraction coupled with 96-well plate
           system as innovative high-throughput configuration for the determination
           of endocrine disrupting compounds by high-performance liquid
           chromatography-fluorescence and diode array detection
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Daniela Lopes, Adriana Neves Dias, Josias Merib, Eduardo Carasek This paper describes a new configuration of the hollow fiber renewal liquid membrane (HFRLM) procedure for the high-throughput determination of the endocrine disrupting compounds 4-nonylphenol, 4-octylphenol, 4-tert-octylphenol, methylparaben, ethylparaben and bisphenol A using a 96-well plate system and high-performance liquid chromatography. In this configuration, cylindrical blades were adapted as a support for polypropylene membranes used as supported liquid membranes in the HFRLM approach. The proposed configuration exhibited important advantages including high-throughput, low solvent and sample consumption, and good analytical performance. The optimized extraction conditions were achieved with the use of a mixture comprised of 50:50 v/v 1-octanol:hexane as the supported liquid membrane, sample pH 5, extraction solvent 15 μL (hexane) and extraction time 45 min. The limits of quantification varied from 0.5 μg L−1 for 4-octylphenol to 15 μg L−1 for methylparaben and ethylparaben and the r2 ranged from 0.9908 for methylparaben to 0.9992 for 4-tert-octylphenol. HFRLM combined with the use of a 96-well plate provides an environmentally-friendly configuration. It offers good accuracy when applied to analyze water samples, with relative recoveries ranging from 72 to 130%, for 4-octylphenol and 4-nonylphenol, respectively, and precision varying from 1 to 14.3%, for 4-nonylphenol at 1.0 μg L−1 and bisphenol A at 8.0 μg L−1, respectively.Graphical abstractImage 1
  • Application of chemometric methods to XRF-data – A tutorial review
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Vitaly Panchuk, Irina Yaroshenko, Andrey Legin, Valentin Semenov, Dmitry Kirsanov X-ray fluorescence (XRF) spectrometry is a modern method of element analysis, widely applied in forensic science, archeology, geochemistry and other fields. Chemometric data processing tools and approaches may help XRF to become even more informative. These tools allow for convenient data visualization, exploration of hidden relations in the data, classification of samples and quantitative treatment of noisy and overlapped spectra. This review describes the most popular chemometric techniques employed in XRF studies and provides typical examples of such applications.Graphical abstractImage 1
  • Opportunities for green microextractions in comprehensive two-dimensional
           gas chromatography / mass spectrometry-based metabolomics – A review
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): João R. Belinato de Souza, Fernanda F.G. Dias, Jaqueline D. Caliman, Fabio Augusto, Leandro W. Hantao Microextractions have become an attractive class of techniques for metabolomics. The most popular technique is solid-phase microextraction that revolutionized the field of modern sample preparation in the early nineties. Ever since this milestone, microextractions have taken on many principles and formats comprising droplets, fibers, membranes, needles, and blades. Sampling devices may be customized to impart exhaustive or equilibrium-based characteristics to the extraction method. Equilibrium-based approaches may rely on additional methods for calibration, such as diffusion-based or on-fiber kinetic calibration to improve bioanalysis. In addition, microextraction-based methods may enable minimally invasive sampling protocols and measure the average free concentration of analytes in heterogeneous multiphasic biological systems. On-fiber derivatization has evidenced new opportunities for targeted and untargeted analysis in metabolomics. All these advantages have highlighted the potential of microextraction techniques for in vivo and on-site sampling and sample preparation, while many opportunities are still available for laboratory protocols. In this review, we outline and discuss some of the most recent applications using microextractions techniques for comprehensive two-dimensional gas chromatography-based metabolomics, including potential research opportunities.Graphical abstractGreen, highly efficient sample preparation for GC × GC-based metabolomics.Image 1
  • Outside Front Cover
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s):
  • Label-free cytosensing of cancer cells based on the interaction between
           protein and an electron-transfer carbohydrate-mimetic peptide
    • Abstract: Publication date: 21 December 2018Source: Analytica Chimica Acta, Volume 1040Author(s): Kazuharu Sugawara, Hideki Kuramitz, Toshihiko Kadoya We used an electron-transfer carbohydrate-mimetic peptide (YYYYC) to construct an electrochemical cytosensing system. Magnetic beads were modified with either asialofetuin (ASF) or soybean agglutinin (SBA) to evaluate the effect on cell sensing. Because SBA binds to the galactose residue that exists at the terminals of the carbohydrate chains in ASF, the target protein was accumulated on the protein magnetic beads. SBA is an example of N-acetylgalactosamine- and galactose-binding proteins that readily combine with YYYYC. When the peptides and protein-immobilized beads competed for a target protein, the peak current of the peptides changed according to the concentration of the protein at the 10−12 M level. Next, human myeloid leukemia cells (K562 cell) were measured using the peptide and the carbohydrate chains on the cell surface that recognize SBA. The electrode response was linear to the number of K562 cells and ranged from 1.0 × 102 to 5.0 × 103 cells mL−1. In addition, detection of a human liver cancer cell (HepG2 cell) was carried out using interactions with the peptide, the ASF receptors in HepG2 cells, and the carbohydrate chains of ASF. The peak currents were proportional and ranged between 5.0 × 101 and 1.5 × 103 cells mL−1. When the values estimated from an electrochemical process were compared with those obtained by ELISA, the results were within the acceptable range of measurement error.Graphical abstractImage 1
  • Flavanols react preferentially with quinones through an electron transfer
           reaction, stimulating rather than preventing wine browning
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Lingjun Ma, Andrew L. Waterhouse Wine oxidation changes the chemistry, sensory profile and color of wines. In wine oxidation, phenolics are oxidized to quinones and these reactive compounds can be quenched by sacrificial nucleophiles, such as the A-ring on flavanoids, preventing oxidative damage from the loss of desirable flavor molecules. The “catechol” B-ring on flavanoids, in contrast, can be oxidized by quinones through electron transfer reactions that lead to flavanoid quinones, precursors of browning products. Here we compared the rate of flavanoids reacting by either nucleophilic quinone quenching, or by electron transfer to generate flavanoid quinones. Our approach is based on mathematical modeling of reaction data to derive the rate constants of reactions of A-ring quenching vs B-ring electron transfer with caffeic acid quinone, by fitting the predicted loss of precursors and the appearance of products (or derivatives) with experimental data collected by LC/MS. The rate constant of the electron transfer reaction of caffeic acid quinone towards 4-methyl-catechol was fast (k4MC  = 3.43E-2 mLmol−1sec−1) but nucleophilic reactions with afzelechin (kAfz  = 2.53E-3 mLmol−1sec−1) or malvidin-3-glucoside (kMal  = 5.34E-3 mLmol−1sec−1), were much slower. No reaction was detected between caffeic acid quinone and isorhamnetin. Additionally, the electron transfer reaction rate of catechin and caffeic acid quinone was much faster at pH 7 (1.22E-02 mLmol−1sec−1) vs pH 3.5 (1.79E-03 mLmol−1sec−1). These results help explain why the reaction of catechin and caffeic acid quinone favors the formation of browning products, and more so at higher pH values. Furthermore, bisulfite reacted with quinones faster than the electron transfer reactions, preventing the browning observed in the reaction of catechin with caffeic acid quinone in the absence of bisulfite.Graphical abstractImage 1
  • Silver-filled MWCNT nanocomposite as a sensing element for voltammetric
           determination of sulfamethoxazole
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Abdollah Yari, Azim Shams Here, we introduce a new electrode based on Silver-filled multi-walled carbon nanotube (Ag-MWCNT) and methyltrioctyl ammonium chloride (MTOAC) for highly sensitive voltammetric measurement of Sulfamethoxazole (SMX). The electrode showed an electrocatalytic activity as it led to the diminution of the overpotential and an increase in peak current for SMX oxidation in a phosphate buffer solution (pH 6.0).Analysis of surface topography and electrochemical properties of the modified electrode was examined by TEM, EDX and EIS, respectively. Electrochemical performance of the modified electrode was investigated with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques for determination of SMX in aqueous solution. In addition, the oxidation process was found to be dependent on the pH of the buffer solution. Under optimal conditions, a linear relationship between the oxidation current and SMX concentration was found in a range 0.05–70 μM (R2 = 0.997) with a detection limit of 0.01 μM after 2 min of accumulating time. The electrode was successfully used to quantify SMX in pharmaceutical formulations and human urine by DPV.Graphical abstractImage 1
  • Detection and quantification of the toxic marine microalgae Karlodinium
           veneficum and Karlodinium armiger using recombinase polymerase
           amplification and enzyme-linked oligonucleotide assay
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Anna Toldrà, Míriam Jauset-Rubio, Karl B. Andree, Margarita Fernández-Tejedor, Jorge Diogène, Ioanis Katakis, Ciara K. O'Sullivan, Mònica Campàs Karlodinium is a dinoflagellate responsible for fish-killing events worldwide. In Alfacs Bay (NW Mediterranean Sea), the presence of two Karlodinium species (K. veneficum and K. armiger) with different toxicities has been reported. This work presents a method that combines recombinase polymerase amplification (RPA) with an enzyme-linked oligonucleotide assay (ELONA) to identify, discriminate and quantify these two species. The system was characterised using synthetic DNA and genomic DNA, and the specificity was confirmed by cross-reactivity experiments. Calibration curves were constructed using 10-fold dilutions of cultured cells, attaining a limit of detection of around 50,000 cells/L, far below the Karlodinium spp. alert threshold (200,000 cells/L). Finally, the assay was applied to spiked seawater samples, showing an excellent correlation with the spiking levels and light microscopy counts. This approach is more rapid, specific and user-friendly than traditional microscopy techniques, and shows great promise for the surveillance and management of harmful algal blooms.Graphical abstractImage 1
  • Potassium-induced ionic conduction through a single nanofluidic pore
           modified with acyclic polyether derivative
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Mubarak Ali, Ishtiaq Ahmed, Saima Nasir, Ivana Duznovic, Christof M. Niemeyer, Wolfgang Ensinger Solid-state nanofluidic pores have been attracting considerable attention of scientific community because of their structural and chemical resemblance with biological ion channels for mimicking biological processes in living systems. Compared to ion channels, synthetic nanopores exhibit high stability, control over pore dimensions (size and geometry) and their surface chemical properties can be tuned on demand. Therefore, they are considered perfect candidates to design and develop nanofluidic sensory devices by introducing a variety of functional moieties on the inner pore surface. Here, we present a nanofluidic pore for the recognition of potassium cations using acyclic polyether derivative in confined environment. To this end, amine terminated acyclic polyether derivative (bis-podand–NH2) is synthesized and covalently coupled with the carboxylic acid groups on the single conical nanopore walls prepared in polymer membrane. The bis-podand moieties fixed on the pore walls in the presence of potassium cation yield recognition domain for the specific binding of K+ cation. Therefore, the changes in rectified ion flux are only noticed on exposure to potassium chloride solution due to formation of positively charged bis-podand–K+ complexes on the pore surface. In contrast, for the case of other alkali metal chloride solutions, only slight changes in the ion current rectification are noticed. We believe that the proposed device provides a strategy to develop and miniaturize different nanofluidic pore based sensors for the efficient detection of other cations/anions by simply changing the length of polyethylene glycol units.Graphical abstractImage 1
  • A wide-color-varying ratiometric nanoprobe for detection of norepinephrine
           in urine samples
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): M. Amin Farahmand Nejad, Forough Ghasemi, M. Reza Hormozi-Nezhad Owing to its dual role as a hormone and neurotransmitter, norepinephrine (NE) detection is of great significance to biomedical diagnosis. In the present work, we have explored intense green fluorescence of poly (norepinephrine) (PNE) nanoparticles synthesized by oxidizing NE in alkaline condition, in combination with red fluorescent bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) for naked-eye detection of NE. The effect of sodium hydroxide on the emission behavior of NE was studied. The surface morphology and optical properties of PNE nanoparticles were characterized by UV–Vis, fluorescence, FTIR, Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS) techniques. For ratiometric sensing of NE, red fluorescent BSA-AuNCs were served as an internal reference while NE delivered a new emission peak at 527 nm, resulting in a wide distinguishable color change from strong red into red, pink, orange, and green under a UV lamp. The ratiometric approach was demonstrated to be highly sensitive and selective for NE detection against even structurally similar biomolecules with a detection limit of 49 nmol L−1. Furthermore, the proposed method was successfully applied to determine NE in urine samples.Graphical abstractImage 1
  • Detection of chloramphenicol using a novel apta-sensing platform based on
           aptamer terminal-lock in milk samples
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Mahbobeh Javidi, Mohammad Reza Housaindokht, Asma Verdian, Bibi Marzieh Razavizadeh In this paper, a novel apta-sensing colorimetric platform for rapid detection of chloramphenicol (CAP) in raw milk was developed. The AuNPs are stabilized by short-sequences aptamers against salt induced aggregation and this is the base of most colorimetric aptasensors development. However, the statute shows low sensitivity for the long-sequence aptamers. Herein, we propose an alternative strategy that use intact long-sequence aptamers for develop a highly sensitive AuNP-based colorimetric aptasensor. Determination of CAP in animal derived foods is an urgent demanded in the effort to minimize food safety risk. Therefore, we chose it as the representative model to construct the colorimetric sensing platform based on aptamer terminal-lock (ATL). In the ATL, intact aptamer was used as a molecular recognition element and a short-sequence oligonucleotide serving as a locker probe (LP) which is complementary of aptamer terminal fragments. By formation of aptamer/target complex, the LP leaves the ATL and adsorbs on the surface of AuNPs, leading to the AuNPs stabilization against salt-induced aggregation. This aptasensor shows a low limit of detection (0.03 nM) with high selectivity toward CAP. Moreover, the designed sensing platform was successfully applied to detect CAP in the milk samples. These results demonstrate our introduced label-free method for CAP detection is simple, sensitive, and highly selective.Graphical abstractImage 1
  • Lectin-mediated in situ rolling circle amplification on exosomes for
           probing cancer-related glycan pattern
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Yimei Feng, Yuna Guo, Yiran Li, Jing Tao, Lin Ding, Jie Wu, Huangxian Ju Exosomal surface glycans play important roles in microvesicle protein sorting and exosome-cell interactions, and also provide promising biomarkers for various diseases. However, in situ detection techniques for exosomal glycans are largely lacking. In this work, an exosomal array is fabricated for probing cancer-related exosomal glycan signatures by lectin recognition-mediated in situ rolling circle assembly of fluorophore-labeled DNA. Different from commonly used lectin array, the proposed strategy enables the direct and amplified conversion of glycan recognition signals to fluorescence detection signals. Focusing on tumor-associated glycans including sialic acids, fucose and truncated O-glycans, the method has been used not only to compare glycan patterns between exosomes with different origins, but also to reveal the specific exosomal glycan characteristics compared to their parent cells. The limits of detection were identified to be 5.4 × 106 and 1.3 × 106 particles mL−1 for HeLa and PANC-1 exosomes, respectively. The dynamic ranges were 4.7 × 105 to 4.7 × 108, 4.7 × 108 to 4.7 × 109 for HeLa exosomes, and 4.7 × 105 to 1.2 × 109, 1.2 × 109 to 4.7 × 109 particles mL−1 for PANC-1 exosomes. The remodeling of exosomal glycans can also be monitored as demonstrated on the cleavage of sialic acids under sialidase treatment. It could be anticipated that this strategy would become a powerful tool for development of exosome-based glyco-biomarkers and elucidation of biological significance of exosomal glycans.Graphical abstractImage 1
  • Magnetic-bioluminescent-nanoliposomes for ultrasensitive and portable
           detection of protein biomarkers in blood
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Peng Liu, Xueen Fang, Hongmei Cao, Mingli Gu, Jilie Kong, Anmei Deng Protein biomarkers play an important role in the diagnosis and treatment of disease. Herein, we report an ultrasensitive magnetic-bioluminescent-nanoliposome based technique using a portable ATP luminometer for the point-of-care testing (POCT) of protein biomarkers in blood. In this study, we use alpha-fetoprotein (AFP, a protein biomarker associated with hepatocellular carcinoma) as a model protein. The bioluminescent nanoliposomes conjugated to magnetic particles (LBM) enabled target protein capture, isolation and detection. In this assay, we use a portable magnetic bead separation pen to simplify the steps. The output RLUs (relative light units) had a linear correlation with AFP concentration between 0.05 and 1000 ng/mL, with a limit of detection of 0.016 ng/mL. Our LBM assay for AFP based on the portable luminometer exhibited high specificity for AFP, with no cross-reactivity with other proteins tested at 25 ng/mL. Forty clinical samples (twenty AFP positive and twenty AFP negative) were tested by the LBM assay, and the results were in good agreement with those determined by electrochemiluminescence, with relative deviations of less than 10%. The successful application of magnetic-bioluminescent-nanoliposomes with a portable ATP luminometer system to detect protein biomarkers in blood has opened a new avenue for biomarker testing. Thus, our LBM assay holds great potential as a POCT assay for use in clinical diagnostics.Graphical abstractImage 1
  • Ultrasensitive fluorescent detection of nucleic acids based on label-free
           enzymatic-assisted cascade signal amplification
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Yingfeng Qin, Suqi Liao, Yufeng Huang, Jingjin Zhao, Shulin Zhao A simple and homogenous label-free fluorescent method based on target-triggered and enzymatic-assisted isothermal cascade signal amplification was established for nucleic acid detection. This amplification method consists of two circuits that depend on polymerase and nicking endonuclease. In the presence of a target, a hairpin probe was opened to initiate the polymerization and nicking reaction, producing target analogues and G-rich sequences, and releasing the original target DNA. The released target and produced target analogues then trigger a new amplification cycle. Large amounts of G-rich sequences were generated through this cascade amplification process. The fluorogenic dye thioflavin T (ThT) specifically recognized G-rich sequences to form a G-quadruplex/ThT complex, which induced a strong fluorescence intensity. The approach was ultrasensitive for nucleic acid detection, and the detection limit was as low as 5.6 fM. The system discriminates single-nucleotide mutations in DNA and provides a promising strategy for nucleic acid detection in complex biological samples. This simple, label-free and ultrasensitive approach is a promising tool for biomedical research and clinical diagnostics.Graphical abstractImage 1
  • Facile preparation of Silicon/ZnO thin film heterostructures and
           ultrasensitive toxic gas sensing at room temperature: Substrate dependence
           on specificity
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): C.A. Betty, Khushwant Sehra, K.C. Barick, Sipra Choudhury Two types of silicon-Zinc oxide (ZnO) heterostructures were prepared simply by depositing (drop casting) chemically prepared ZnO nanoparticles onto single crystalline (p-type) silicon substrates (Si) as well as electrochemically prepared p-type porous silicon (PS). ZnO nanoparticles and PS/ZnO structures were characterized structurally by various techniques. By depositing in-plane gold contacts on the heterostructures, gas sensors were fabricated and characterized electrochemically by dc and ac impedance measurements. The PS/ZnO sensors showed specific response at room temperature for NO2 with increase in current and no significant response for other reducing and oxidizing gases. The sensor is sensitive to 200 ppb NO2 at 25 °C with 35% change in current and 50 s response time. Temperature dependent studies of sensor in the range of 25–100 °C have shown maximum sensitivity at 40 °C (50% change for 200 ppb) with decreasing sensitivity thereafter (23% change at 60 °C), indicating the suitability of the sensor till 60 °C. Alternatively Si/ZnO heterostructures showed maximum response with NO2, along with lesser specific responses for SO2 and NH3. Detailed multifrequency impedance studies with temperature suggested the role of space charge layers at various interfaces in the charge transport properties of PS/ZnO and Si/ZnO heterostructures resulting in their specific gas sensing properties.Graphical abstractImage 1
  • A novel fluorimetric sensing strategy for highly sensitive detection of
           phytic acid and hydrogen peroxide
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Zhengyi Qu, Weidan Na, Yixin Nie, Xingguang Su In this paper, we developed a sensitive sensor for phytic acid (PA) and hydrogen peroxide (H2O2) detection based on glutathione-functionalized graphene quantum dots (GQDs@GSH). The fluorescence of GQDs@GSH was found to be effectively quenched by Fe3+ ions via photo-induced electron transfer (PET) process. Upon the addition of PA to GQDs@GSH/Fe3+ system, the fluorescence of GQDs@GSH was significantly restored due to the strong chelating and reducing ability of PA, Fe3+ ions could be reduced to Fe2+ ions by PA and formed PA/Fe2+ complex. Therefore, the “off–on” fluorescence method was constructed to detect PA by using GQDs@GSH/Fe3+ as a fluorescent probe. Furthermore, the method can be used for the detection of H2O2. H2O2 can destroy the chelate structure of PA/Fe2+, release Fe2+ ions and oxidize Fe2+ ions to produce Fe3+ ions, leading to the fluorescence quenching of GQDs@GSH again. Under optimal conditions, the fluorescence sensing platform showed good linear relationship between the relative fluorescence intensity I/I0 and the concentration of PA and H2O2 in the range of 0.05–3 μmol L−1 and 0.5–10 μmol L−1, respectively. The detection limits of PA and H2O2 were 14 nmol L−1 and 0.134 μmol L−1, respectively. Furthermore, the fluorescence assay method was also applied in real sample analysis and satisfactory results were obtained.Graphical abstractImage 1
  • High-throughput screening of phthalate-containing objects in the
           kindergartens by ambient mass spectrometry
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Hung Su, Min-Zong Huang, Jo-Han Chou, Ting-Hao Chang, Yu-Min Jiang, Yi-Tzu Cho, Sy-Chyi Cheng, Ming-Tsang Wu, Jentaie Shiea High-throughput screening of plastic products in children's living environment is necessary to identify phthalate-containing objects for the concern of public health and safety. A novel strategy of probe collecting technique combined with ambient mass spectrometry was developed to carry out the large-scale sample analysis. Analytes from the surface of approximately 500 objects each in two kindergartens in Taiwan were collected using the same number of the metallic probes. After being delivered to laboratory, the analytes on the probes were analyzed with thermal desorption-electrospray ionization/mass spectrometry (TD-ESI/MS). As sample pretreatment was unnecessary, the analysis of phthalates on a probe was completed within 30 s enabling high-throughput screening of a large number of objects. All procedure including sampling and TD-ESI/MS analysis together with report writing for a kindergarten was completed in one day. A reasonable relative standard deviation (2 ng) of phthalates and 40–60% of the objects in the kindergartens contained more than one kind of phthalate.Graphical abstractImage 1
  • An available strategy for elemental composition determination of organic
           impurities in commercial preparations based on accurate mass and peak
           ratio of isotopic fine structures (IFSs) by dual mode combined-FT-ICR-MS
           and fraction collection technology
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Xintong Li, Xiaowen Chu, Xue Wang, Ran Yin, Xiaoxue Zhang, Yangyang Zhao, Aihua Song, Fei Han A strategy to determine the elemental composition of organic impurities in commercial preparations was established by combining high-performance liquid chromatography (HPLC)-Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and fraction collector with direct infusion-FT-ICR-MS (DI-FT-ICR-MS). Under HPLC-FT-ICR-MS mode, all impurities in model sample were chromatographically separated and collected by fraction collector according to their retention time. The accurate mass of each impurity and their candidate formulae under 1 ppm mass tolerance were calculated. Subsequently, theoretical isotopic fine structures (IFSs) of the candidate formulae were generated. Furthermore, the collected fractions were tested and the experimental IFSs of impurities were acquired by DI-FT-ICR-MS mode. Finally, the elemental composition of all impurities was decisively determined by comparing the experimental and theoretical IFSs. Our results demonstrate that the combined strategy is effective in separating impurities and acquiring accurate mass by HPLC-FT-ICR-MS, obtaining the appropriate samples by fraction collection technology for DI-FT-ICR-MS, and acquiring the IFSs of impurities by DI-FT-ICR-MS. It could be concluded that the strategy is an accurate and standard independent approach to determine the elemental composition of organic impurities in commercial preparations.Graphical abstractImage 1
  • Simultaneous observation of concurrent two-dimensional carbon and
           chlorine/bromine isotope fractionations of halogenated organic compounds
           on gas chromatography
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Caiming Tang, Jianhua Tan It has been reported that isotope fractionation can occur on gas chromatography (GC), yet little is known about concurrent dual-elements isotope fractionations on GC. Revelation of concurrent two-dimensional carbon and chlorine/bromine isotope fractionations of halogenated organic compounds (HOCs) on GC may be of important significance for compound-specific isotope analysis (CSIA). This study presents an in-depth investigation of the two-dimensional C and Cl/Br isotope fractionations of HOCs on GC using GC-double focus magnetic-sector high resolution mass spectrometry (GC-DFS-HRMS). The two-dimensional C and Cl/Br isotope fractionations of four organochlorines and four bromobenzenes on GC were simultaneously measured by GC-DFS-HRMS. The isotope fractionations were evaluated with isotope ratios, relative variations of isotope ratios (△hE) and isotope fractionation extents (ΛhE). All the HOCs exhibited significant inverse C and Cl/Br isotope fractionations, with Λ13C of 38.14‰–307.56‰, Λ37Cl of 59.60‰–146.85‰, and Λ81Br of 25.89‰–142.10‰. The isotope fractionations were significant in both ends of chromatographic peaks, while the isotope ratios in center retention-time segments were the closest to comprehensive isotope ratios in the whole peaks. Significant correlations between C isotope fractionation and Cl/Br isotope fractionation were observed, indicating that the isotope fractionations might have strong relationships and/or be dominated by similar factors. Relevant mechanisms for the two-dimensional C and Cl/Br isotope fractionations were tentatively proposed on basis of a modified two-film model and the theories related to zero point energy. The results of this study gains new insights into concurrent two-dimensional isotope fractionation behaviors of HOCs during physical processes, and are conducive to CSIA studies involving C, Cl and Br for obtaining high-quality data, particularly to dual-elements CSIA of C and Cl/Br.Graphical abstractImage 1
  • A disposable and ultrasensitive ITO based biosensor modified by
           6-phosphonohexanoic acid for electrochemical sensing of IL-1β in human
           serum and saliva
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Elif Burcu Aydın, Mustafa Kemal Sezgintürk In this study, we constructed a new and sensitive ITO based electrochemical immunosensor for detection of interleukin 1β (IL-1β), a cancer biomarker found in serum and saliva. 6-phosphonohexanoic acid (PHA) was used as a biomolecule immobilization matrix for the first time. Anti-IL-1β antibody was utilized as a biorecognition molecule that immobilized onto carboxyl groups of 6-phosphohexanoic acid (PHA) via amide bond. Selective interaction between anti- IL-1β antibodies and IL-1β antigens was investigated by Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV) and Single Frequency Impedance (SFI) methods. The surface characterization of the immunosensor was performed by fourier transform infrared spectroscopy (FTIR), raman spectroscopy, scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) in order to illustrate individual steps of biosensor construction. Under the optimized experimental conditions, the change in impedance was proportional to IL-1β concentrations in the range of 0.025–3 pg/mL (R2 = 0.99) with detection limit of 7.5 fg/mL. The reproducibility, repeatability, stability, and specificity of the developed immunosensor were analyzed. In addition, the developed immunosensor was successfully utilized for the determination of IL-1β in serum and saliva samples by using the standard addition method with recoveries of 96.7–105.4%. This immunosensor was applicable for the requirements of routine analysis with respect to performance, functionality and cost.Graphical abstractImage 1
  • Multifunctional solid-state electrochemiluminescent chemosensors and
           aptasensor with free-standing active sites based on task-specific
           pyrene-terminated polymers via RAFT polymerization
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Yuanhong Xu, Tao Chen, Jing Sun, Jingquan Liu Based on the flexible molecular engineering technique of reversible addition-fragmentation chain transfer (RAFT) polymerization, various polymers carrying positive or negative charges and different terminal groups such as pyrene or tertiary amine were synthesized for fabricating multifunctional solid-state electrochemiluminescent (ECL) sensors. Accordingly, the chemosensors immobilizing the ECL probe or co-immobilizing the ECL probe and the coreactant were realized for the quantification of small molecules (e.g., tripropylamine, tetracycline), and an aptasensor was developed for the specific and sensitive lysozyme assay (limit of detection: 0.1 ng/mL). All of the sensors were realized via a simple design exploiting the π−π stacking and electrostatic interactions. It was confirmed that the proposed strategy is simple but universal for the fabrication of versatile ECL sensors that showed simplicity, cost-effectiveness, high sensitivity, long-term stability, and excellent reproducibility.Graphical abstractMultifunctional sensitive and selective solid-state electrochemiluminescent chemosensors and aptasensor with free-standing active sites were established based on various task-specific pyrene-terminated polymers, which were synthesized via the flexible molecular engineering technique of reversible addition-fragmentation chain transfer polymerization. All of these sensors were achieved just through a simple but universal design via π−π stacking and electrostatic interactions.Image 1
  • Quantitative assessment of the metabolic products of iron oxide
           nanoparticles to be used as iron supplements in cell cultures
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): J. García Fernández, C. Sánchez-González, J. Bettmer, J. Llopis, N. Jakubowski, U. Panne, M. Montes-Bayón Iron nanoparticles (NPs) metabolism is directly associated to human health due to their use as anemia treatment and should be studied in detail in cells. Here we present a speciation strategy for the determination of the metabolic products of iron oxide nanoparticles coated by tartaric and adipic acids in enterocytes-like cell models (Caco-2 and HT-29). Such methodology is based on the use of SDS-modified reversed phase high performance liquid chromatography (HPLC) separation using inductively coupled plasma-mass spectrometry (ICP-MS) as Fe selective detector. Post-column isotope dilution analysis is used as quantification tool by adding 57Fe as isotopically enriched standard. To assess the separation capability of the method, two different iron nanostructures: iron sucrose nanoparticles -Venofer®- used as model suspension and iron tartrate/adipate-modified nanoparticles, both of about 4 nm (core size) were evaluated. The two nanostructures were injected into the system showing good peak profiles and quantitative elution recoveries (>80%) in both cases. In addition, both nanoparticulate fractions could be based-line separated from ionic iron species, which needed to be complexed with 1 mM citrate to elute from the column. Exposed cells up to 0.5 mM of iron tartrate/adipate-modified nanoparticles were specifically treated to extract the internalized NPs and the extracts examined using the proposed strategy. The obtained results revealed the presence of three different fractions corresponding to nanoparticle aggregates, dispersed nanoparticles and soluble iron respectively in a single chromatographic run. Quantitative experiments (column recoveries ranging from 60 to 80%) revealed the presence of the majority of the Fe in the nanoparticulated form (>75%) by summing up the dispersed and aggregate particles. Such experiments point out the high uptake and low solubilization rate of the tartrate/adipate NPs making these structures highly suitable as Fe supplements in oral anemia treatments.Graphical abstractImage 1
  • “Metal oxide -based heterostructures for gas sensors”- A
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Dario Zappa, Vardan Galstyan, Navpreet Kaur, Hashitha M.M. Munasinghe Arachchige, Orhan Sisman, Elisabetta Comini This review focuses on the synthesis and chemical sensing characterization of metal oxide heterostructures reported since 2012. Heterostructures exhibit strong interactions between closely packed interfaces, showing superior performances compared to single structures. Surface effects appear thanks to the magnification of nanostructures’ surface leading to an enhancement of surface related properties (the base of chemical sensors working mechanism).The combination of different metal oxides to form heterostructures further improves the selectivity and/or other important sensing parameters. A very large number of different morphologies and structures have been proposed, each one exhibiting peculiar sensing properties towards specific chemical compounds. Among the different preparation methodologies, a significant number has been performed by means of hydrothermal method. However, the combination of various fabrication methods seems a very efficient strategy to obtain metal oxide-based heterostructures with different morphologies and dimensions such as core-shell nanostructures, one-dimensional heterostructures, two-dimensional layered heterojunctions, and three-dimensional hierarchical heterostructures.Despite all extraordinary advances in both material science and nanotechnology and the results achieved with heterostructured chemical sensors, there are few points that still deserve further studies and investigations, such as possible diffusion across the junctions, reproducibility of the fabrication process, synergistic or catalytic effects among the materials forming the heterostructures and influence/stability of the contacts. Moreover, perfect control over their growth is mandatory for their application in commercial devices. Only a careful understanding of the growth and the interface properties could fill the existing gap between laboratory studies and real-world exploitation of these heterostructures.Graphical abstractImage 1
  • Outside Front Cover
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s):
  • Ultra-high performance supercritical fluid chromatography in impurity
           control: Searching for generic screening approach
    • Abstract: Publication date: 18 December 2018Source: Analytica Chimica Acta, Volume 1039Author(s): Kateřina Plachká, František Švec, Lucie Nováková In this study, 63 compounds measured as 10 individual mixtures containing in each case an active pharmaceutical ingredient and its relevant impurities, and additional set of 7 basic beta blockers were analyzed using ultra-high performance supercritical fluid chromatography with UV and mass spectrometry detection. The separations were accomplished using 8 different stationary phases (diol, diethylamine, 2-picolylamine, 1-aminoanthracene, BEH 2-ethylpyridine, BEH, CSH pentafluorophenyl, and HSS C18 SB), 6 modifiers (methanol, ethanol, isopropanol, methanol/acetonitrile, methanol/ethanol, ethanol/acetonitrile) and 5 additives in methanol (0.1% formic acid, 10 mmol/L ammonium formate, 10 mmol/L ammonium acetate, 0.4% ammonium hydroxide, and 2% water).The resulting chromatograms were evaluated using 6 selected parameters: number of eluted peaks, number of separated peaks, resolution between active pharmaceutical ingredient and following impurity, peak symmetry, peak width at 50% of the peak height, and selectivity. Volatile additives such as ammonium formate, ammonium acetate, and especially ammonium hydroxide provided overall generic approach with very good chromatographic performance. Combined modifier methanol/acetonitrile (1:1) was important for separations of some critical pairs in case of neutral compounds. Diol stationary phase proved its suitability for wide range of applications when the separations of all mixtures were satisfactory on this column, except for vardenafil and beta blockers mixture. HSS C18 SB stationary phase offered unique complementary selectivity especially for analysis of structurally close compounds and/or isomers.Graphical abstractImage 1
  • A novel nucleic acid fluorescent sensing platform based on nanostructured
           films of intrinsically conducting polymers
    • Abstract: Publication date: Available online 12 October 2018Source: Analytica Chimica ActaAuthor(s): Graciela C. Pedro, Filipe D.S. Gorza, Romário J. da Silva, Kamila T.O. do Nascimento, Juan C. Medina-Llamas, Alicia E. Chávez-Guajardo, José J. Alcaraz-Espinoza, Celso P. de Melo When fluorophores attach to nanostructured films of intrinsically conducting polymers (ICPs), a quenching of their fluorescence may occur. We have exploited these characteristics for the development of polymeric films that can be used in a simple and efficient molecular diagnosis protocol based on the selective detection of nucleic acids. Our procedure rests on the fact that the fluorescence of 6-carboxyfluorescein-labeled single-stranded DNA (FAM-ssDNA) probes is quenched upon their immobilization on nanostructured ICP – polypyrrole (PPY) and polyaniline (PANI) – films deposited on polyethylene terephthalate (PET) substrates. Hybridization occurs whenever a sample with the complementary sequence is brought in contact with the immobilized probe, with the newly formed ds-DNA chains detaching from the flexible polymeric film and causing the restoration of the fluorescence. This sensing system exhibits a low background signal that depends on both the thickness and hydrophobicity of the films. As a model system, we used a FAM-ssDNA probe specific for the Leishmania infantum parasite. The results confirm this procedure as a simple, fast and highly sensitive scheme for the recognition of the target DNA, with a detection limit of the 1.1 nM and 1.3 nM for the PPY/PET and PANI/PET films, respectively. In addition, this biosensor has excellent stability and exhibits a good and reproducible performance even when used for the direct detection of ssDNA in relatively complex biological samples.Graphical abstractImage 1
  • Experimental analysis of waveguide-coupled surface-plasmon-polariton cone
    • Abstract: Publication date: Available online 26 September 2018Source: Analytica Chimica ActaAuthor(s): Charles K.A. Nyamekye, Qiaochu Zhu, Russell Mahmood, Stephen C. Weibel, Andrew C. Hillier, Emily A. Smith Experimental data for waveguide-coupled surface-plasmon-polariton (SPP) cones generated from dielectric waveguides is presented. The results demonstrate a simpler route to collect plasmon waveguide resonance (i.e., PWR) data. In the reverse-Kretschmann configuration (illumination from the sample side) and Kretschmann configuration (illumination from the prism side), all the waveguide modes are excited simultaneously with p- or s-polarized incident light, which permits rapid acquisition of PWR data without the need to scan the incident angle or wavelength, in the former configuration. The concentric SPP cone properties depend on the thickness and index of refraction of the waveguide. The angular intensity pattern of the cone is well-matched to simulation results in the reverse-Kretschmann configuration, and is found to be dependent on the polarization of the incident light and the polarization of the waveguide mode. In the Kretschmann geometry, all waveguide-coupled SPP cones are measured at incident angles that produce attenuated light reflectivity. In addition, the enhanced electric field produced under total internal reflection allows high signal-to-noise ratio multimodal spectroscopies (e.g., Raman scattering, luminescence) to measure the chemical content of the waveguide film, which traditionally is not measured with PWR.Graphical abstractImage 1
  • Application of CdTe/CdS/ZnS quantum dot in immunoassay for aflatoxin B1
           and molecular modeling of antibody recognition
    • Abstract: Publication date: Available online 26 September 2018Source: Analytica Chimica ActaAuthor(s): Fuyuan Zhang, Bing Liu, Yan Zhang, Junping Wang, Yang Lu, Juan Deng, Shuo Wang In order to develop a sensitive immunoassay for Aflatoxin B1 (AFB1) monitoring, a hybridoma secreting anti-AFB1 monoclonal antibody with high binding affinity was screened. A new type of CdTe/CdS/ZnS quantum dot was synthesized and conjugated with an artificial antigen for use as a fluorescent probe in a simple one-step fluorescence immunoassay (FLISA). The developed FLISA allowed a sensitive determination of AFB1 in cereal samples in a wide linear range, from 0.08 to 1.97 ng mL−1, with a detection limit of 0.01 ng mL−1 in cereal samples. The corresponding immunoglobulin genes of the Fab fragment were cloned and sequenced, and expression of Fab was successfully verified in HEK293 cells, with a KD value of 1.09 × 10−7 mol L−1 for AFB1. To investigate the interactions between the antibody and AFB1, molecular docking, molecular dynamic simulation, and quantum-chemical computation were performed on AFB1 and a homology model of the Fab fragment. Our results showed that residues Ser32, Trp93, and Trp98 played the most important roles in the binding through hydrogen bonds formation, Pi-Pi stacked/Pi-alkyl interactions, and van der Waals interactions. In addition, the electrostatic potential study of AFB1 demonstrated that electrostatic interactions also played an important role in the recognition process. Results from theoretical studies provide guidance for hapten design and antibody improvement through genetic engineering.Graphical abstractImage 1
  • Preparation of platinum-based 'cauliflower microarrays’ for enhanced
           ammonia gas sensing
    • Abstract: Publication date: Available online 25 September 2018Source: Analytica Chimica ActaAuthor(s): Ghulam Hussain, Leigh Aldous, Debbie S. Silvester In amperometric gas sensors, the flux of gas to electrode surfaces determines the analytical response and detection limit. For trace concentration detection, the resulting low current prevents the miniaturisation of such sensors. Therefore, in this study, we have developed repeating arrays of nanostructures which maximise flux towards their surface. Unique platinum 3D cauliflower-shaped deposits with individual floret-shaped segments have been produced in a single step electrodeposition process. The confined walls of recessed microelectrode arrays (10 μm in diameter, 90 electrodes) are utilized to produce these structures with a high surface area. Distinct segments are observed, with the gaps corresponding to electrodes adjacent in the microarray; thus the majority of the deposits face the primary diffusion zones. The sizes and shapes of the deposits are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) and the largest structures are found to be 22 ± 1 μm in width and 7.9 ± 0.2 μm in height over the microhole. These modified electrodes are employed to detect ammonia using the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C2mim][NTf2], as an electrolyte. Current responses on the cauliflower arrays were seven times higher for linear sweep voltammetry and ca. 12 times higher for chronoamperometry, relative to the bare microrrays, and limits of detection were less than 1 part per million of ammonia (gas phase concentration). This work highlights the use of modified microarrays with highly accessible 3D structures for enhanced electroanalytical detection of analyte species at ultra low concentrations.Graphical abstractImage 1
  • Gravitational field flow fractionation: Enhancing the resolution power by
           using an acoustic force field
    • Abstract: Publication date: Available online 25 September 2018Source: Analytica Chimica ActaAuthor(s): Jae Youn Hwang, Sangyeon Youn, In-Hwan Yang An acoustic field flow fractionation (FFF) device was developed to fractionate a micro-particle mixture on the basis of the particle diameter using an acoustic force field in a carrier liquid flow. In the acoustic FFF channel used in the device, ultrasound waves generated from piezoelectric transducers driven by a sinusoidal signal of 2.02 Mhz propagated into the carrier liquid flow and built up a quarter-wavelength ultrasound standing wave field across the channel height. It was experimentally demonstrated that the acoustic field with a pressure node plane at the bottom surface of the channel reduced the thickness of the particle diffusion layer in a stagnant liquid proportional to the applied voltage driving the piezoelectric transducer. In the size-dependent particle separation, the particle mixture flowing through the acoustic FFF channel experienced an acoustic radiation force in the gravitational direction. As a result, suppressing the diffusion of small particles, particles were transported along the bottom surface of the channel with the local velocity of the carrier liquid at the particle center. The developed acoustic FFF device successfully fractionated a fluorescent micro-particle mixture (1, 3, 5, and 10 μm diameter), whereas the 3 and 5 μm particles were not fractionated in the FFF device using only the gravitational force field due to the diffusion of 3 μm particles.Graphical abstractImage 1
  • Silver-based polymeric ionic liquid sorbent coatings for solid-phase
           microextraction: Materials for the selective extraction of unsaturated
    • Abstract: Publication date: Available online 25 September 2018Source: Analytica Chimica ActaAuthor(s): María J. Trujillo-Rodríguez, Jared L. Anderson A new generation of silver-based polymeric ionic liquid (PIL) sorbent coatings has been developed and applied in solid-phase microextraction (SPME). The new materials are based on ionic liquid monomers formed by cations containing the silver(I) ion coordinated with two 1-vinylimidazole ligands. Up to seven different silver-based PIL sorbent coatings were developed by polymerizing the silver-IL monomer in the presence of either silver bis[(trifluoromethyl)sulfonyl]imide, and/or a dicationic ionic liquid crosslinker. The obtained sorbent coatings were found to possess adequate thermal stability despite the presence of the silver(I) ions. Thermal desorption of the analytes at 175 °C was effectively used without any significant decrease in extraction efficiency. The developed sorbent coatings were used in two different applications: the determination of alkenes/alkynes via headspace SPME and the determination of unsaturated fatty acids using direct-immersion SPME. In the former approach, the silver-based PILs were particularly selective for the determination of unsaturated compounds with terminal double bonds such as 1,5-hexadiene, 2-methyl-1,5-hexadiene, and 1,8-nonadiene. A study of the extraction mechanism of the analytes to the sorbent coating revealed a competitive partitioning of the analytes. In the second approach, the most selective silver-based PILs were applied for the determination of oleic acid, linoleic acid, and linolenic acid. After proper optimization of the method, the coatings were found to be more or as sensitive as the commercial polydimethylsiloxane fiber. Limits of detection between 2.6 and 8.2 μg L−1 in ultrapure water and from 12 to 14 μg L−1 in tap water were obtained for the best silver-based PIL, with relative standard deviations lower than 13% in all cases at a spiked level of 160 μg L−1. Finally, the fiber was effectively applied for the analysis of rinse water from a dairy farm, with adequate detection of the analytes at concentrations between 52 and 179 μg L−1.Graphical abstractImage 1
  • Quantitative determination of potential urine biomarkers of respiratory
           illnesses using new targeted metabolomic approach
    • Abstract: Publication date: Available online 25 September 2018Source: Analytica Chimica ActaAuthor(s): Mona M. Khamis, Darryl J. Adamko, Randy W. Purves, Anas El-Aneed The diagnosis of asthma and chronic obstructive pulmonary disease (COPD) can be challenging due to the overlap in their clinical presentations in some patients. There is a need for a more objective clinical test that can be routinely used in primary care settings. Through an untargeted 1H-NMR urine metabolomic approach, we identified a set of endogenous metabolites as potential biomarkers for the differentiation of asthma and COPD. A subset of these potential biomarkers contain 7 highly polar metabolites of diverse physicochemical properties. To the best of our knowledge, there is no liquid chromatography-tandem mass spectrometry (LC-MS/MS) method that evaluated more than two of the target metabolites in a single analytical run. The target metabolites belong to the families of monosaccharaides, organic acids, amino acids, quaternary ammonium compounds and nucleic acids, rendering hydrophilic interaction liquid chromatography (HILIC) an ideal technology for their quantification. Since a clinical decision is to be made from patient data, a fully validated analytical method is required for biomarker validation. Method validation for endogenous metabolites is a daunting task since current guidelines were designed for exogenous compounds. As such, innovative approaches were adopted to meet the validation requirements. Herein, we describe a sensitive HILIC-MS/MS method for the quantification of the 7 endogenous urinary metabolites. .Detection was achieved in the multiple reaction monitoring (MRM) mode with polarity switching, using quadrupole-linear ion trap instrument (QTRAP 6500) as well as single ion monitoring in the negative-ion mode. The method was fully validated according to regulatory guidelines. Linearity was established between 6 to 21000 ng/mL and quality control samples demonstrated acceptable intra- and inter-day accuracy (85.7%-112%), intra- and inter-day precision (CV%
  • A rhodamine B-based probe for the detection of HOCl in lysosomes
    • Abstract: Publication date: Available online 24 September 2018Source: Analytica Chimica ActaAuthor(s): Shi-Li Shen, Xiao-Qing Huang, Hong-Li Jiang, Xiao-Hui Lin, Xiao-Qun Cao A rhodamine B-based derivative (RL1) was developed as a specific fluorescent probe for HOCl. Meanwhile, morpholine moiety was introduced into the probe. It was found that the probe could display highly selective, sensitive and naked-eye detection upon the addition of HOCl. And the detection limit (LOD) was calculated to be as low as 2.8 nM. Furthermore, cellular confocal microscopic studies revealed that the introduction of morpholine moiety realized the lysosome-targeting capability. Moreover, RL1 was successfully applied for the imaging of endogenous HOCl with low cytotoxicity. Therefore, all the desirable features made probe RL1 particularly suitable for HOCl detection in aqueous buffer solution samples as well as the bio-imaging applications.Graphical abstractImage 1 A lysosome-targeting fluorescent probe (RL1) for HOCl was developed based on rhodamine B. Importantly, probe RL1 was capable of targeting lysosome and detecting endogenous HOCl.
  • Multiplexed assessment of the surface density of DNA probes on DNA
           microarrays by surface plasmon resonance imaging
    • Abstract: Publication date: Available online 24 September 2018Source: Analytica Chimica ActaAuthor(s): László Simon, Róbert E. Gyurcsányi In terms of hybridization assays surface plasmon resonance imaging (SPRi) offers high throughput, label-free and real-time monitoring of the binding kinetics. This requires DNA microarrays on bare or modified gold SPRi chips, which are generally premade by an off-line microspotting procedure. Therefore, the surface density of the immobilized probes is not known although it is an essential quality control parameter, especially, when it can vary in a broad range as in case of self-assembled thiol-labeled DNAs on gold surface. Here we show that the small molecular weight ruthenium(III) hexamine complex (RuHex) introduced earlier for electrochemical quantitation of DNA coverage on gold electrodes can be used also in SPRi to assess the surface density of DNA probes in DNA microarrays. A single injection of RuHex solution allows the simultaneous visualization and quantification of the surface density of DNA probes (ranging in this study from 4 × 1011 to 1.7 × 1013 molecules cm−2) on all spots of a microarray made by microspotting thiol labeled short DNA probes both in prehybridized and single-stranded form on a gold SPRi chip. The methodology was applied to determine the effect of the surface density of DNA probes on the hybridization efficiency and kinetics of complementary microRNAs, using hsa-miR-208a-3p as model. Single mismatch duplexes were found to be more effectively destabilized than fully complementary duplexes by steric hindrance at large surface densities of the DNA probes, which offers an effective mean to increase single mismatch selectivity.Graphical abstractImage 1
  • Low-cost and environment-friendly synthesis of carbon nanorods assembled
           hierarchical meso-macroporous carbons networks aerogels from natural
           apples for the electrochemical determination of ascorbic acid and hydrogen
    • Abstract: Publication date: Available online 24 September 2018Source: Analytica Chimica ActaAuthor(s): Nan Wang, Yashuang Hei, Jingju Liu, Mimi Sun, Tianze Sha, Mehboob Hassan, Xiangjie Bo, Yingna Guo, Ming Zhou In this work, the low-cost carbon nanorods assembled hierarchical meso-macroporous carbons networks aerogels (CNs-HMCNAs) was environment-friendly synthesized from a cheap and abundant biomass of apples (Malus pumila Mill) for the first time. The biomass of apples derived CNs-HMCNAs exhibited the unique hierarchical meso-macroporous structure with large specific surface area and high density of edge defective sites. At the CNs-HMCNAs modified GCE (CNs-HMCNAs/GCE), the electron transfer between the glassy carbon electrode (GCE) and the ascorbic acid (AA) (or hydrogen peroxide (H2O2)) was effectively enhanced, and thus induced a low overvoltage for AA electrooxidation (or H2O2 electroreduction). As an electrochemical AA (or H2O2) sensor, the CNs-HMCNAs/GCE exhibited wider linear range, lower detection limit, higher sensitivity and stability than GCE and the carbon nanotubes modified GCE (CNTs/GCE). In particular, the CNs-HMCNAs/GCE showed great potential feasibility in the practical determination of AA (in AA injection, Vitamin C tablet and kiwi juice) or H2O2 (in human urine, milk and beer).Graphical abstractImage 1
  • Peptide cleavage-based electrochemical biosensor coupling graphene oxide
           and silver nanoparticles
    • Abstract: Publication date: Available online 24 September 2018Source: Analytica Chimica ActaAuthor(s): Fanyu Meng, Haixuan Sun, Yue Huang, Yuguo Tang, Qiang Chen, Peng Miao Herein, a novel electrochemical biosensor for sensitive analysis of prostate specific antigen (PSA) is demonstrated. A specific peptide is employed on the gold electrode as a molecular recognition element for target induced cleavage. In the absence of PSA, graphene oxide (GO) is directly immobilized on the peptide modified electrode, which triggers the aggregation of silver ions and subsequent reduction reaction to form silver nanoparticles (AgNPs). Well defined sharp silver stripping peak can thus be achieved, which stands for a highly characteristic solid-state Ag/AgCl reaction. However, in the presence of PSA, the peptide is specifically recognized and cleaved. The resulted product on the electrode surface cannot aid the immobilization of GO and subsequent formation of AgNPs. Therefore, electrochemical response is decreased remarkably, which can be used to indicate the concentration of PSA. This work demonstrates that the combination of the transduction of peptide cleavage event with GO/AgNPs nanocomposites is a promising attempt for PSA analysis with high sensitivity and selectivity.Graphical abstractImage 1
  • Combination of field amplified sample injection and hydrophobic
           interaction electrokinetic chromatography (FASI-HIEKC) as a signal
           amplification method for the determination of selected macrocyclic
    • Abstract: Publication date: Available online 23 September 2018Source: Analytica Chimica ActaAuthor(s): Piotr Kowalski, Ilona Olędzka, Alina Plenis, Natalia Miękus, Michał Pieckowski, Tomasz Bączek In this study, a field amplified sample injection (FASI) and hydrophobic interaction electrokinetic chromatography (HIEKC) method has been developed for the separation of five macrolide antibiotics: spiramycin, ivermectin, tylosin, josamycin, rapamycin, and one ansamycin drug – rifamycin. By the manipulation of both the sample and separation buffer compositions, their pH values and molarity, a systematic approach has been achieved to maximize analyte differential electrophoretic mobility and signal amplification. The impact of the sample solution composition and the injection mode on the signal amplification effect of the six tested antibiotics was also investigated. Moreover, the influence of the injection of the sample and the water plug on the quantity, symmetry and height of the analyte signal was demonstrated. All the analytes were completely resolved in less than 8 min in an uncoated fused-silica capillary of 75 μm internal diameter (I.D.) x 50 cm length. The electrophoretic separations were performed in a 60% (v/v) acetonitrile and 20 mM phosphate electrolyte system (pH 7.1) with an applied voltage of 25 kV. The established method was validated and confirmed to be applicable for the determination of the active ingredients in a quality control analysis.Graphical abstractImage 1
  • Preparation of a poly(ethyleneimine) embedded phenyl stationary phase for
           mixed-mode liquid chromatography
    • Abstract: Publication date: Available online 23 September 2018Source: Analytica Chimica ActaAuthor(s): Xiujun Ren, Chengxia Hu, Die Gao, Qifeng Fu, Kailian Zhang, Fengjiao Zu, Jing Zeng, Lujun Wang, Zhining Xia A poly(ethyleneimine) embedded phenyl mixed-mode stationary phase was prepared through epoxide ring opening reaction. Elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) were used to characterize whether functional groups have been modified on the surface of silica successfully. The researches of chromatographic performance for designed column were divided to four parts. The retention behavior under reversed-phase mode was studied using polycyclic aromatic hydrocarbons (PAHs), positional isomers and alkylbenzenes. The retention characteristic under hydrophilic interaction mode was studied by nucleosides, nucleobases and flavonoids. The chromatographic performance of anion exchange mode was evaluated by benzoic acids and phenols. Due to a high content of amino and phenyl groups on the stationary phase, aromatic amines were chosen for the evaluation of retention mechanisms of benzene ring attraction and amino repulsion. The investigations about effects of mobile phase constitution and pH on retention demonstrated the mixed-mode retention mechanisms of the column. Furthermore, due to amino selectivity of the column, a method for the rapid separation and determination of phenylenediamines in hair dye was established. And both linear correlation coefficients of p-diaminobenzene and m-diaminobenzene in concentration range from 0.1 to 30 μg mL−1 were over 0.999. In conclude, the prepared mixed-mode stationary phase could realize various separation modes by adjusting chromatographic conditions, and it had the potential for the rapid separation and determination of aniline compounds in various complex samples.Graphical abstractImage 1
  • Detection of antibiotic residues in pork using paper-based microfluidic
           device coupled with filtration and concentration
    • Abstract: Publication date: Available online 22 September 2018Source: Analytica Chimica ActaAuthor(s): Azadeh Nilghaz, Xiaonan Lu This work demonstrates a sensitive and rapid method for the detection of antibiotic residues in food samples by employing the filtration behaviour of paper combined with aggregation and precipitation of chemical reagents. Using this concept, we successfully determined the presence of oxytetracycline and norfloxacin residues in pork using metal complexation on microfluidic paper-based analytical devices (μPADs). The base substrate (top layer of the device) was fabricated by printing letter channels of the words “oxytetracycline” and “norfloxacin” before functionalization with copper (II) sulfate pentahydrate in 0.5 M sodium hydroxide and iron (III) nitrate nanohydrate in 5 mM ammonia solution for the detection of oxytetracycline and norfloxacin separately. A transition metal hydroxide formed upon reaction that created solid precipitates on paper and allowed antibiotic residues to bind to the metal ions via coordination chemistry. The metal ion-antibiotic complex could form on the filter paper and generated a visible color change with the detection limit of 1 ppm for both oxytetracycline and norfloxacin in pork. This procedure of filtration and concentration in combination with a simple text-reporting approach allows the end users to achieve a low limit of detection as well as easy result interpretation in food safety monitoring.Graphical abstractImage 1
  • On-line solvent exchange system: Automation from extraction to analysis
    • Abstract: Publication date: Available online 22 September 2018Source: Analytica Chimica ActaAuthor(s): Elisenda Fornells, Emily F. Hilder, Robert A. Shellie, Michael C. Breadmore Removal of organic solvent from sample extracts is required before analysis by reversed phase HPLC to preserve chromatographic performance and allow for bigger injection volumes, boosting sensitivity. Herein, an automated on-line extraction evaporation procedure is integrated with HPLC analysis. The evaporation occurs inside a 200 μm microfluidic channel confined by a vapor permeable membrane. A feedback control algorithm regulates evaporation rate keeping the output flow rate constant. The evaporation process across this membrane was firstly characterized with water/solvent mixtures showing organic solvent removal capabilities. This system allowed continuous methanol, ethanol and acetonitrile removal from samples containing up to 80% organic solvent. An evaporative injection procedure was developed demonstrating the use of the device for fully integrated extract reconstitution coupled to HPLC analysis, applied to analysis of the antibiotic chloramphenicol in milk samples. Sample reconstitution and collection was performed in less than 10 min and can be executed simultaneously to HPLC analysis of the previous sample in a routine workflow, thus having minimal impact on the total sample analysis time when run in a sequence.Graphical abstractImage 1
  • Thinning shell thickness of CuInS2@ZnS quantum dots to boost
           detection sensitivity
    • Abstract: Publication date: Available online 21 September 2018Source: Analytica Chimica ActaAuthor(s): Yun Tian, Chenqi Xin, Zhenlan Fang, Xiaodie Fang, Jia Zhou, HaiDong Yu, Lin Li, Qiang Ju Quantum dots (QDs), drawing large attention during the past three decades, have been extensively applied in lighting, display, and biodetection. However, the mechanism for their ability in biodetection, especially in recognizing toxic metal ions, has scarcely been explored. In this work, three sets of CuInS2@ZnS QDs systems with inert shell thickness varying from 1.1 to 4.1 nm have been performed. As the shrinkage of inert shell, QDs not only show red-shift emission but also demonstrate more sensitive and higher response to the added Cd2+. The thin-shell CuInS2@ZnS QDs could detect 0.91 nM Cd2+, and could further detect 4.36 nM Cd2+ when integrated with paper-based platform. Importantly, thin-shell CuInS2@ZnS QDs combined with paper-based platform can detect 105.86 nM Cd2+ even just applying mobile phone as detector and hand-held UV lamp as excitation resource. The mechanism is further proposed based on the energy transfer routes. The thin inert shell can not completely protect the emissive core away from the surface defects, but it can neither exclude the energy transfer from the surface to the emissive core. The added Cd2+ would facilitate the formation of CdS on the surface of QDs, which not only can alleviate the surface defects but also can transfer energy to emissive CuInS2, thus thinning the thickness of inert shell greatly boost the detection sensitivity.Graphical abstractThinning the thickness of inert shell of CuInS2@ZnS has been demonstrated to modulate the capability of QDs to recognize Cd2+, and moreover, CuInS2@ZnS QDs combining with paper-based platform could detect out trace Cd2+ when just using UV lamp as excitation resource and smartphone camera as detector.Image 1
  • Acid-base properties of phosphoric and acetic acid in aprotic organic
           solvents – A complete thermodynamic characterisation
    • Abstract: Publication date: Available online 20 September 2018Source: Analytica Chimica ActaAuthor(s): D. Barišić, V. Tomišić, N. Bregović Knowledge regarding the acid-base behaviour in non-aqueous media has remained relatively scarce in spite of its importance for many aspects of chemistry. The research presented in this work fills some of particularly important gaps in the corresponding thermodynamic data.We report on a detailed study of acid-base properties of dihydrogen phosphate and acetate in aprotic organic solvents (acetonitrile, dimethyl sulfoxide, and dimethylformamide). It was found that several processes, i.e. protonation, homoassociation, and dimerisation play important roles in defining the basicity of these widely important anions. In the case of dihydrogen phosphate, formation of higher homoassociates (two anions, one acid molecule and vice versa) was detected, whereas acetate formed only simple homoassociates of 1:1 stoichiometry. The dimerisation of dihydrogen phosphate and acetic acid were confirmed to be important processes as well. The thermodynamics of the above mentioned reactions was characterised in detail by means of various experimental methods: ITC, spectrophotometry, NMR-spectroscopy, and conductometry. Reliable equilibrium constants and other thermodynamic reaction functions were determined. The obtained results were discussed in terms of hydrogen bonding potential of the anions and their conjugated acids, as well as solvent properties, i.e. their ability to solvate the species involved in the studied processes.Graphical abstractImage 1
  • Sensitive and selective colorimetric detection of alkaline phosphatase
           activity based on phosphate anion-quenched oxidase-mimicking activity of
           Ce(Ⅳ) ions
    • Abstract: Publication date: Available online 20 September 2018Source: Analytica Chimica ActaAuthor(s): Hongwei Song, Hangyu Wang, Xin Li, Yinxian Peng, Jianming Pan, Xiangheng Niu As alkaline phosphatase (ALP) plays crucial roles in disease warning and dephosphorylation-related cellular regulation, it is widely recognized as an important biomarker for clinical diagnosis. In this work, we proposed a facile colorimetric assay based on phosphate anion-quenched oxidase-mimicking activity of Ce(Ⅳ) ions for sensitive and selective detection of ALP activity. Free Ce(Ⅳ) ions exhibited a strong oxidase-like capability (providing a 40-fold catalytic turnover number compared with CeO2) to catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into its blue product TMBox mediated by dissolved O2 at neutral pH, thus triggering a remarkable color reaction visually. When PO43− was added, its strong affinity to Ce(Ⅳ) ions rapidly precipitated the free Ce(Ⅳ) ions, resulting in the quenching of their enzymatic ability. Given that ALP catalyzed the hydrolysis of adenosine triphosphate to produce PO43−, determination of ALP activity could be achieved using the colorimetric assay with no need of complicated instrumentation and protocol. As demonstrated, our assay offered a highly sensitive readout for ALP activity in two linear scopes of 0–50 U L−1 and 50–250 U L−1, providing a detection limit down to 2.3 U L−1. Besides, it could provide specific response toward ALP against other enzymes and biological species. Furthermore, the developed assay was successfully applied to evaluate ALP activity in human plasma accurately and reliably, indicating its great promise as a powerful and convenient tool for monitoring of ALP activity in clinical practice.Graphical abstractImage 1
  • Exploring a phage-based real-time PCR assay for diagnosing Acinetobacter
           baumannii bloodstream infections with high sensitivity
    • Abstract: Publication date: Available online 19 September 2018Source: Analytica Chimica ActaAuthor(s): Jun Luo, Mengwei Jiang, Jin Xiong, Junhua Li, Xiaoxu Zhang, Hongping Wei, Junping Yu In the present study, we developed a phage-based real-time quantitative PCR (qPCR) methodology for sensitive diagnosis of bloodstream infection (BSI) caused by Acinetobacter baumannii (A. baumannii). An isolated A. baumannii phage p53 was used for Taqman qPCR through detecting phage replication in live A. baumannii cells in serum samples. At the phage concentration of 103 PFU/mL, the sensitive detection of A. baumannii (down to 10 CFU in 100 μL serum) has been obtained within 4 h in spiked serum samples without bacteria isolation and DNA extraction. Subsequent testing of 22 simulated serum samples spiked by different strains has shown that the results from the phage-based Taqman qPCR method have 100% agreement with the spiked concentrations of the bacteria. The assay built in this study, gathering all the advantages for detections of high rapidity, high sensitivity, good specificity, being able to detect only live bacteria not dead bacteria and no DNA extraction or purifications, can be developed to detecting other bacterial pathogens in serum or other complicated samples through switching to other types of phages and realize the rapid and sensitive detection of bacteria in BSI, which would potentially be applied for fast diagnosis in sepsis clinically.Graphical abstractImage 1
  • Synthetic cannabinoid isomers characterization by MALDI-MS3 imaging:
           Application to single scalp hair
    • Abstract: Publication date: Available online 19 September 2018Source: Analytica Chimica ActaAuthor(s): Angéline Kernalléguen, Christine Enjalbal, Jean-Claude Alvarez, Omar Belgacem, Georges Léonetti, Daniel Lafitte, Anne-Laure Pélissier-Alicot New designer drugs, as synthetic cannabinoids (SCs), continuously appear on the market and are booming due to their cannabis-like effect. New generation of smokable SCs, structurally dissimilar from Δ9-tetrahydrocannabinol (THC), have isomers with distinguishable pharmacokinetic parameters and therefore different in vivo effects. The isoforms are misidentified using conventional techniques such as gas or liquid chromatography coupled to mass spectrometry - or tandem mass - spectrometry. The aim of this study was to differentiate three positional isomers (JWH-007, JWH-019 and JWH-122) in single human hair samples, which store numerous substances revealing a way of life and consumption style.Matrix-assisted laser desorption/ionization (MALDI) combined with imaging is an innovative and powerful tool used since few years, especially in forensic research. Herein, we propose an innovative method to monitor the drugs of abuse consumption through direct mapping of the compounds with a high spatial distribution in human hair samples, by state-of-art imaging MALDI-MSn. Three positional SC isomers (JWH-007, JWH-019 and JWH-122) were analysed using high and low fragmentation energy and the resulting MS/MS and even MS3 spectra differentiated the SCs. The MALDI-MS/MS and MS3 imaging was performed on hair soaked in a mixture of the three SCs as well as on hair from self-reported SC user, proving the potential of the technique for a forensic use. Keeping in mind that spatial distribution of organics from whole hair remains a challenge, the described methodology is a very promising analytical tool to probe the consumption of complex drugs and obtain correlation with its origin.Graphical abstractImage 1
  • Carbon quantum dots encapsulated in super small platinum nanocrystals
           core-shell architecture/nitrogen doped graphene hybrid nanocomposite for
           electrochemical biosensing of DNA damage
    • Abstract: Publication date: Available online 19 September 2018Source: Analytica Chimica ActaAuthor(s): Qi Zhang, Qiuyue Zhao, Mingxuan Fu, Xinyu Fan, Haijun Lu, Haiyang Wang, Yufan Zhang, Huan Wang In this work, carbon quantum dots (CQD) encapsulated in super small platinum nanocrystals core-shell architecture/nitrogen doped graphene hybrid nanocomposite (CQD@PDA@PtNCs-NGR) was design synthesized. Without using any capping reagent, stabilizer and surfactant, very small CQD was served as template and anchoring point for the synthesis of Pt NCs with a super small size (2.25 nm) and a uniform distribution. Meanwhile, dopamine (DA) was used as bridging agent, positioning agent and weak reducing agent to make Pt2+ grow on the CQD. Combine the high dispersed Pt NCs with high specific surface area and high conductivity of NGR, the CQD@PDA@PtNCs-NGR shows excellent electrocatalytic performance towards the biosensing of DNA damage biomarker- 8-Hydroxy-2′-deoxyguanosine (8-OH-dG). A very low detection limit of 0.45 nM and 0.85 nM (S/N = 3), a wide linear range of 0.013 μM–109.78 μM and a high sensitivity of 7.912 μA μM−1cm−2 and 4.190 μA μM−1cm−2 were obtained. The fabricated CQD@PDA@PtNCs-NGR realized the detection of 8-OH-dG in human urine practical sample. Furthermore, CQD@PDA@PtNCs-NGR was applied for the determination of 8-OH-dG generated from damaged DNA and damaged guanine (G), respectively. This work effectively combines the electrochemical signal of 8-OH-dG with DNA damage, confirms the mechanism of DNA damage, which might pave a new way to establish the associations between degree of DNA damage and 8-OH-dG.Graphical abstractImage 1
  • Multi-Element Analysis of Size-Segregated Fine and Ultrafine Particulate
           via Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry
    • Abstract: Publication date: Available online 12 October 2018Source: Analytica Chimica ActaAuthor(s): Sabrina Rovelli, Winfried Nischkauer, Domenico M. Cavallo, Andreas Limbeck In this study a novel and reliable Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) measurement protocol for the elemental characterization of size-segregated particulate was developed. Special efforts were made to improve and optimize sample pre-treatment steps and LA operating conditions to avoid some critical drawbacks encountered during analysis and make the particulate samples suitable for an accurate and reproducible LA-ICP-MS analysis, regardless of the mass loading on each filter. For example, a new approach for dust-fixation on the sample-carrier was developed using a glycerol coverage, which allowed to overcome problematic sample losses during the ablation process. Under the optimum conditions, dust samples, blank filters and standards for calibration were analyzed by multiple rastering of defined spot areas. Quantitative analysis was accomplished with dried-micro droplets of aqueous standard solutions. Derived method detection limits varied between 0.001 and 0.1 ng m–3 and allowed even for the smallest particle fraction quantitative measurements. The accuracy of LA-ICP-MS results was verified by comparison with conventional ICP-MS analysis of selected PM samples after sample mineralization. The proposed LA treatment procedure benefits from a simple and fast sample preparation, thus overcoming the laborious pre-treatment steps required for wet chemical digestion. Moreover, the better sensitivity of the LA-ICP-MS approach provided more complete information about the mass concentration and size-distribution of the investigated elements, thus allowing to deeper investigate the composition of the most dangerous PM fractions in terms of health concern.Graphical abstractImage 1
  • Rapid quantitative analysis with low matrix effects of capsaicin in
           various samples by thermal desorption carbon fiber ionization mass
    • Abstract: Publication date: Available online 11 October 2018Source: Analytica Chimica ActaAuthor(s): Qiang Zhang, Xiaopan Liu, Zhongquan Li, Yue Su, Yinlong Guo It is difficult to conduct rapid quantitative studies by direct analysis of mass spectrometry because of the matrix effects. In order to overcome the matrix effects in rapid quantitative analysis of complex sample and to find a rapid mass spectrometry method for capsaicin quantitation, the thermal desorption carbon fiber ionization mass spectrometry (TD-CFI-MS) was developed and optimized. TD-CFI-MS allows timesaving, less cost, less solvent consumption and no auxiliary gas. In this method the metal ceramics heater (MCH) was used for analyte desorption. The protonated water clusters in carbon fiber ion source provided proton for analytes through ion-molecular interactions. Desorption and ionization processes were separated in time and space so the analyte was less affected by the matrix during ionization, and the signal intensity of the analyte was enhanced. The matrix effects were investigated by the quantitative analysis of capsaicin in various samples using TD-CFI-MS, and the results were within 93.3-97.6 % which indicated that almost no significant effects on the quantitation of capsaicin by this method. Finally, TD-CFI-MS was successfully applied for the quantitation of capsaicin in various real samples including foods and medicines indicating that this technique was a valuable strategy.Graphical abstractImage 1
  • Detecting Transcription Factors with Allosteric DNA-Silver Nanocluster
    • Abstract: Publication date: Available online 11 October 2018Source: Analytica Chimica ActaAuthor(s): Bingzhi Li, Yue Chen, Jing Wang, Qiaoyun Lu, Wanying Zhu, Jieping Luo, Junli Hong, Xuemin Zhou Sensitive and efficient detection of protein markers, such as transcription factors (TFs), is an important issue in postgenomic era. In this paper, we report a DNA nanodevice, allosteric DNA-silver nanocluster switches (AgSwitches), for TFs detection. The mechanism of this nanodevice is based on the binding-induced allostery whereby the binding between AgSwitches and TFs alters the conformation of AgSwitches. This alteration brings DNA-silver nanocluster (DNA-AgNCs) and guanine-rich enhancer sequences (GRS) into close proximity, generating fluorescent enhancement for quantifications. Our results revealed that the sequence design of AgSwitches can be rationally optimized according to stimulated free energy, and we demonstrated that this method can not only be used for detecting TFs in nuclear extracts of cells, but also be developed as a tool for screening inhibitors of TFs. Overall, this work expanded the category allosteric DNA nanodevices by first introducing DNA-AgNCs into this area, and the obtained method was efficient for TFs-related investigations.Graphical abstractImage 1
  • Facile Synthesis of Stable CdTe/CdS QDs Using Dithiol as Surface Ligand
           for Alkaline Phosphatase Detection Based on Inner Filter Effect
    • Abstract: Publication date: Available online 11 October 2018Source: Analytica Chimica ActaAuthor(s): Guobin Mao, Qin Zhang, Yeling Yang, Xinghu Ji, Zhike He Alkaline phosphatase (ALP) is a universal and important hydrolase that has been proved to be associated with several diseases. Herein, a simple and effective method was proposed for ALP detection based on the inner filter effect of p-nitrophenol (pNP) on the fluorescence of CdTe/CdS quantum dots (QDs). For the preparation of CdTe/CdS QDs, Na2TeO3 was used as the Te source, and dithiol as the S source and surface ligand. The as-prepared CdTe/CdS QDs show good fluorescence properties, such as high quantum yield (∼80%), and good chemical/photo-stability. pNP is a hydrolysate of p-nitrophenol phosphate disodium salt under the catalysis of ALP, which could effectively quench the fluorescence of QDs due to the absorption spectra of pNP overlaps well with the excitation spectra of the CdTe/CdS QDs. Therefore, the prepared CdTe/CdS QDs could be applied for ALP detection. A good linear relationship ranging from 2.2 to 220 U/L was obtained with the limit of detection as low as 0.34 U/L. In addition, this method was successfully applied for the assay of ALP in human serum with the satisfactory results.Graphical abstractA simple and effective method was proposed for ALP detection based on inner-filter effect of p-nitrophenol on the fluorescence of CdTe/CdS QDs. CdTe/CdS QDs were prepared with good fluorescence properties, such as high quantum yield, and good chemical/photo-stability.Image 1
  • A multicolorimetric assay for rapid detection of Listeria monocytogenes
           based on the etching of gold nanorods
    • Abstract: Publication date: Available online 11 October 2018Source: Analytica Chimica ActaAuthor(s): Yushen Liu, Juan Wang, Chao Zhao, Xiaoxiao Guo, Xiuling Song, Wei Zhao, Sijie Liu, Kun Xu, Juan Li Listeria monocytogenes (L. monocytogenes) is one of the most common food-borne pathogens. The authors describe a sensitive and reliable multicolorimetric assay for L. monocytogenes using a sensing system based on TMB2+ etching of gold nanorods. Apt-MNP was used as the capture probe, and IgY-BSA-MnO2 NPs was chosen as an oxidase-like nano-artificial enzyme to oxidize TMB to generate TMB2+. Under the optimized conditions, the longitudinal shift of localized surface plasmon resonances had a linear correlation with the L. monocytogenes concentration in the range between 10 to 106 cfu mL−1. Meanwhile, the sensing system can generate vivid color responses as colorful as a rainbow, and the limit of detection is as low as 10 cfu mL−1 at a glance. Recoveries ranging from 97.4 to 101.3% are found when analyzing spiked food samples without pre-enrichment. In our perception, it shows promise in rapid instrumental and on-site visual detection of L. monocytogenes.Graphical abstractImage 1
  • Exciton energy transfer-based fluorescent sensor for the detection of Hg2+
           through aptamer-programmed self-assembly of QDs
    • Abstract: Publication date: Available online 11 October 2018Source: Analytica Chimica ActaAuthor(s): Huan Guo, Jingshuai Li, Yuewen Li, Dan Wu, Hongmin Ma, Qin Wei, Bin Du Herein, an original exciton energy transfer-based sensitive fluorescence sensor for the determination of Hg2+ has been designed through DNA aptamer-programmed self-assembly of CdTe quantum dots (QDs). In this work, CdTe QDs were applied as fluorescence signal source. The two pieces of T-rich aptamer played a role as molecular recognition probes which could bind to the target Hg2+ specifically. The extent of Hg2+-triggered self-assembly of QDs depended on the concentration of Hg2+, which resulted in an exciton energy transfer effect between QDs, giving an obvious fluorescence signal decrease and red-shift of the fluorescent peak. Based on this principle, we could detect the Hg2+ in two different signal modes. The limit of detection (LOD) was 3.33 nM. The proposed sensing method exhibited its application in detecting Hg2+ in real water samples with satisfactory performance. The results indicated that this proposed sensor will be of great potential in biological and analytical fields.Graphical abstractImage 1
  • A novel electrochemical immunosensor based on catalase functionalized
           AuNPs-loaded self-assembled polymer nanospheres for ultrasensitive
           detection of tetrabromobisphenol A bis(2-hydroxyethyl) ether
    • Abstract: Publication date: Available online 11 October 2018Source: Analytica Chimica ActaAuthor(s): Shuaibing Dong, Shaochen Wang, Eric Gyimah, Nuanfei Zhu, Kun Wang, Xiangyang Wu, Zhen Zhang A competitive immunosensor was established using an electrochemical amperometric strategy for sensitive detection of tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA-DHEE), an important derivative of tetrabromobisphenol A (TBBPA). In this system, the amplified electrochemical signal towards the reduction of hydrogen peroxide (H2O2) was recorded by amperometric method. Meanwhile, the synthetized catalase functionalized AuNPs-loaded self-assembled polymer nanospheres showed an excellent electrocatalytic ability to catalyze H2O2, which was beneficial for strengthening the electrochemical signals. Under the optimized conditions, this method displayed: (i) low detection limits (0.12 ng/mL, 7 times lower than the traditional ELISA with the same antibody); (ii) satisfactory accuracy (recoveries, 78-124%; RSD, 2.1-8.3%) and good agreement with the corresponding ELISA; (iii) low sample consumption (6 μL) and low cost. The proposed approach was applied for investigation of TBBPA-DHEE from environmental waters, and our results indicated that this immunosensor has great potential to detect the trace pollutants in aquatic environments.Graphical abstractImage 1
  • Determination of progesterone in saliva using an electrochemical
           immunosensor and a COTS-based portable potentiostat
    • Abstract: Publication date: Available online 11 October 2018Source: Analytica Chimica ActaAuthor(s): V. Serafín, G. Martínez-García, J. Aznar-Poveda, J.A. Lopez-Pastor, A.J. Garcia-Sanchez, J. Garcia-Haro, S. Campuzano, P. Yáñez-Sedeño, J.M. Pingarrón This paper describes the reliable determination of progesterone (P4) in undiluted saliva making use of a disposable amperometric immunosensors implemented on low-cost and portable device/potentiostat constructed with commercial-off-the-shelf (COTS) components. The immunosensor allows the fast (45 min), selective and sensitive determination (5 pg mL-1 LOD) of P4 using amperometry in stirred solutions. The immunosensor was coupled to the COTS-based potentiostat and amperometry was made into drops of quiescent solutions. No significant differences were apparent between the analytical performance achieved with the immunosensor for P4 using both a conventional and the COST-based potentiostats. The practical applicability of the immunosensor coupled with the COTS-based potentiostat was demonstrated by determining the endogenous P4 content in different undiluted saliva samples with highly variable endogenous contents of the target hormone. The obtained results were in good agreement with those provided by the conventional ELISA methodology and with the contents reported in the literature for samples with similar characteristics. This validated the combined device for the reliable and minimally invasive determination of the target hormone involving a very simple protocol and taking only 45 minutes.Graphical abstractImage 1
  • A Clean-up Method for Determination of Multi-classes of Persistent Organic
           Pollutants in Sediment and Biota Samples with an Aliquot Sample
    • Abstract: Publication date: Available online 10 October 2018Source: Analytica Chimica ActaAuthor(s): Xingru Zhao, Tingting Cui, Rui Guo, Yan Liu, Xing Wang, Yue-xia An, Xiaocui Qiao, Binghui Zheng In the present study, we developed a novel method to simultaneously detect eight classes of persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), polychlorinated naphthalenes (PCNs), organochlorine pesticides (OCPs), short-chain chlorinated paraffins (SCCPs) and Dechlorane Plus (DP), in sediment and fish tissue samples. The samples were extracted by accelerated solvent extraction (ASE) system, and the extracts were purified and fractionated into fraction1 and fraction2 with multi-layer silica gel column, followed by further fractionation using a basic alumina column (fraction1) and a Florisil column (fraction2), respectively. Finally, fractions were analyzed with different chromatographic columns and different detectors according to the properties of a chemical compound. The limit of detection for eight classes of POPs ranged from 1 to 30 pg/gdw in fish tissue samples, and from 1 to 33 pg/gdw in sediment samples, except for SCCPs (from 5.6 to 7.6 ng/g in fish tissue samples, and from 1.2 to 8.3 ng/gdw in sediment samples). The recoveries of eight classes of POPs spiked in fish tissue and sediment samples ranged from 43% to 120%, and from 45% to 115%, respectively. The relative standard deviation (RSD) was less than 25%. The accuracy of method was satisfactorily demonstrated by analysis of standard reference materials NIST SRM 1649b and WMF-01. In addition, the newly developed method was successfully applied for analysis of sediment and fish samples collected from the Baiyangdian Lake.Graphical abstractImage 1
  • A simple modification increases specificity and efficiency of asymmetric
    • Abstract: Publication date: Available online 10 October 2018Source: Analytica Chimica ActaAuthor(s): Zoltán Tolnai, Ákos Harkai, Zsuzsanna Szeitner, Éva Nagyné Scholz, Krisztina Percze, Anna Gyurkovics, Tamás Mészáros Although various methods have been developed to suffice the oligonucleotide demand of molecular biology laboratories, in vitro production of high-purity ssDNAs remains to be a challenging task. We hypothesized that complementing the asymmetric PCR with 3’ phosphate blocked limiting primer decreases the mispriming thus reduces polymerisation of DNA by-products. The presented results attest our assumption that the primer blocked asymmetric PCR (PBA-PCR) selectively produces ssDNA of interest and is even suitable for effective amplification of DNA libraries of large sequence space. The high-throughput sequence analysis demonstrated that PBA-PCR also alleviates the PCR bias obstacle since it does not distort the sequence space. The practicability of the novel method was verified by monitoring the process of SELEX and screening of aptamer candidates using PBA-PCR produced ssDNAs in Amplified Luminescent Proximity Homogeneous Assay. In summary, we have developed a generally applicable method for straightforward, cost-effective production of ssDNA with on demand labelling.Graphical abstractImage 1
  • Fabrication of super pure single−walled carbon nanotube electrochemical
           sensor and its application for picomole detection of olaquindox
    • Abstract: Publication date: Available online 10 October 2018Source: Analytica Chimica ActaAuthor(s): Hongwu Wang, Yanqing Liu, Su Yao, Gengxin Hu In this study, a novel and simple electrochemical sensor (ECS) was fabricated based on super pure single−walled carbon nanotubes (spSWCNTs) modified electrode. The ECS exhibited superior catalytic performance on the electrochemical reduction of olaquindox. A series of experimental parameters were systematically optimized to achieve optimal ECS performance. Compared with the bare gold electrode, the peak current increased 1700 times under the optimal experimental conditions. The ECS exhibited excellent sensitivity for the determination of trace olaquindox. The current response of the modified electrode was linear to the olaquindox concentration in the range of 0.1−500 nM with a detection limit of 30.0 pM (S/N=3). The ECS was successfully applied for electrochemical recognition of olaquindox in real samples. In addition, the spSWCNTs modified electrode also exhibited remarkable electrocatalytic property in a wide potential range, so it had great potential for sensitive detection of various electroactive compounds.Graphical abstractImage 1
  • A near-infrared fluorescent probe based on photostable Si-rhodamine for
           imaging hypochlorous acid during lysosome-involved inflammatory response
    • Abstract: Publication date: Available online 10 October 2018Source: Analytica Chimica ActaAuthor(s): Guo-Jiang Mao, Zhen-Zhen Liang, Jingjing Bi, Hua Zhang, Hong-Min Meng, Li Su, Yi-Jun Gong, Suling Feng, Guisheng Zhang Hypochloric acid (HClO) is mainly distributed in acidic lysosomes of phagocytes and closely associated with numerous physiological and pathological processes, especially inflammatory response. Fluorescent probe has become an important tool for imaging HClO in lysosomes, but suffered from interference from autofluorescence in vivo, phototoxicity to biosamples and photobleaching phenomenon due to their short-wavelength excitation and emission. Unfortunately, up to now, no near-infrared (NIR) lysosome-targetable fluorescent probe has been reported for imaging HClO. In this paper, a near-infrared fluorescent probe Lyso-NIR-HClO for imaging lysosomal HClO was reported for the first time. Lyso-NIR-HClO based on Si-rhodamine is consisted of a morpholine unit as a lysosome-targetable group and a HClO-mediated cyclization reaction site as a response group, which was applied for highly selective and sensitive detection and imaging for endogenous and exogenous HClO in lysosomes, with a linear range from 5.0 × 10-8 to 1.0 × 10-5 M and a detection limit of 2.0 × 10-8 M in vitro. Attributed to NIR emission and excellent photostability of Si-rhodamine, Lyso-NIR-HClO exhibits excellent performances in vivo, such as low interference from intracellular autofluorescence, stable and persistent fluorescence signal and good tissue penetration, which are in favor of accurate, time-lapse and long-term imaging for HClO. Finally, we applied the probe Lyso-NIR-HClO to visualize endogenous HClO during lysosome-involved inflammatory response including bacteria-infected cells and inflamed mouse model with satisfactory results. The above results proved that Lyso-NIR-HClO would be a potentially useful tool for the study of biological functions and pathological roles of HClO in lysosomes, especially role of lysosome in the inflammatory response.Graphical abstractImage 1
  • Self-stacking of exfoliated charged nanosheets of LDHs and graphene as
           biosensor with real-time tracking of dopamine from live cells
    • Abstract: Publication date: Available online 9 October 2018Source: Analytica Chimica ActaAuthor(s): Ayesha Aziz, Muhammad Asif, Muhammad Azeem, Ghazala Ashraf, Zhengyun Wang, Fei Xiao, Hongfang Liu This study introduces a new strategy for periodic stacking of positively charged NiAl layered double hydroxides (LDHs) nanosheets with negatively charged monolayers of graphene (G) by systematically optimizing several parameters in a controlled co-feeding fashion and resultant heterostacked NiAl LDH/G LBL nanocomposites have been practically applied in sensitive detection of dopamine released from live cells as early Parkinson’s disease (PD) diagnostic tool. PD is the second most chronic neurodegenerative disorder with gradual progressive loss of movement and muscle control causing substantial disability and threatening the life seriously. Unfortunately majority of dopaminergic neurons present in substantia nigra of PD patients are destroyed before it is being clinically diagnosed, so early stages PD diagnosis is essential. Because of direct neighboring of extremely conductive graphene to semiconductive LDHs layers, enhanced intercalation capability of LDHs, and huge surface area with numerous active sites, good synergy effect is harvested in heteroassembled NiAl LDH/G LBL material, which in turn shows admirable electrocatalytic ability in DA detection. The interference induced by UA and AA is effectively eliminated especially after the modifying the electrode with Nafion. The outstanding electrochemical sensing performance of NiAl LDH/G LBL modified electrode has been achieved in terms of broad linear range and lowest real detection limit of 2 nM (S/N=3) towards DA oxidation. Benefitting from superior efficiency, biosensor has been successfully used for real-time in-vitro tracking of DA efflux from live human nerve cell after being stimulated. We believe that our biosensing platform of structurally integrated well-ordered LBL heteroassembly by inserting graphene directly to the interlayer galleries of LDHs material will open up new avenue in diseases determination window.Graphical abstractImage 1
  • Determination of 89Sr and 90Sr in fresh cow milk and raw urine using
           crystalline synthetic tunnel manganese oxides and layered metal sulfides
    • Abstract: Publication date: Available online 9 October 2018Source: Analytica Chimica ActaAuthor(s): Pierre-André Pittet, François Bochud, Pascal Froidevaux 89Sr and 90Sr are both fission products of high radiotoxicity, which can be released in significant amounts in the event of a nuclear accident. Radiostrontium isotopes will follow calcium all along the food chain and, after ingestion, accumulate in the bones. Therefore, it is imperative to be able to determine 89Sr and 90Sr in raw milk samples in case of an accidental situation to evaluate the dose given by both radionuclides to the population. Several methods exist for conducting 89Sr and 90Sr determination. However, most of them use at least one chromatographic step to purify strontium. This, unfortunately, increases the analytical time before the results can be released to the authorities. In addition, they often use liquid scintillation counting to determine the 89Sr and 90Sr activities, a method which can handle only one sample at a time. Here we propose using synthetic tunnel manganese oxides such as cryptomelane and todorokite and layered metal sulfides to selectively extract strontium from fresh milk and raw urine in a batch sorption method. We found that the method is very quick and yields very pure sources of (radio)-strontium, which can be counted in a proportional counter. Data (counts per minute) from the counter were fitted to a mathematical expression enabling the simultaneous determination of 89Sr and 90Sr. Because a proportional counter often has several drawers, it is typically possible to measure up to 16 samples at a time. Since cryptomelane is a binding phase easily synthesized in a large quantity, we anticipate that this technique could be an interesting alternative to conventional solid phase extraction chromatography methods.Graphical abstractImage 1
  • Two-phase micro-electromembrane extraction across free liquid membrane for
           determination of acidic drugs in complex samples
    • Abstract: Publication date: Available online 9 October 2018Source: Analytica Chimica ActaAuthor(s): Andrea Šlampová, Pavel Kubáň A dynamic two-phase micro-electromembrane extraction (μ-EME) using electrically induced transfer of charged analytes directly into free liquid membrane (FLM) is proposed as a novel technique for improving enrichment capabilities of μ-EME. The presented set-up employs aqueous sample as donor solution and water immiscible organic solvent (1-octanol) as FLM, which form the two-phase μ-EME system for efficient extraction of model acidic drugs (ibuprofen, ketoprofen, naproxen and diclofenac) from standard solutions, human urine, human serum and wastewater samples. The FLM eliminates migration of matrix components from the complex samples and simultaneously it acts as an acceptor solution for selective trapping and enrichment of the analyte ions. Electrodes are immersed directly into the sample and the FLM and replenishment of analyte ions at the sample/FLM phase interface is accomplished by stirring the sample solution using a conventional laboratory stirrer. At optimized two-phase μ-EME conditions (100 V, 15 min, 1000 rpm) and optimized volume ratio of sample to FLM (480:16 μL), extraction recoveries of 60 – 97% and enrichment factors up to 29.1 were achieved. Determination of the acidic drugs in resulting FLMs was achieved by capillary electrophoresis with ultraviolet detection with good linearity (r2 ≥ 0.9998) and low limits of detection (4 – 20 ng/mL).Graphical abstractImage 1
  • Isobaric duplex based on a combination OF 16O/18O enzymatic exchange and
           labeling with pyrylium salts
    • Abstract: Publication date: Available online 9 October 2018Source: Analytica Chimica ActaAuthor(s): Mateusz Waliczek, Remigiusz Bąchor, Monika Kijewska, Dorota Gąszczyk, Karolina Panek-Laszczyńska, Andrzej Konieczny, Krystyna Dąbrowska, Wojciech Witkiewicz, Joanna Tracz, Magdalena Łuczak, Zbigniew Szewczuk, Piotr Stefanowicz Enzymatic 18O exchange, the well-established approach in comparative proteomics, has some disadvantages such as back exchange of labeled oxygen and overlapping the peak of a labeled peptide with isotopic peaks of an unlabeled one. Herein we demonstrated a simple procedure in which samples digested with a trypsin (with and without H218O) were reacted with unlabeled and quadrupled 13C-labeled pyrylium salt respectively which results in formation of pyridinium cations. Thus, each isobarically labeled peptide containing zero or four 13C atoms in the mass reporter group, during tandem MS/MS forms an unique reporter ion useful for a relative quantitation. Such a sample treatment improves the signal to noise ratio, reduces overlapping of the isotopic peaks and completely eliminates the back exchange problem.Graphical abstractImage 1
  • Sensitive and Robust MALDI-TOF-MS Glycomics Analysis Enabled by Girard’s
           Reagent T On-target Derivatization (GTOD) of Reducing Glycans
    • Abstract: Publication date: Available online 9 October 2018Source: Analytica Chimica ActaAuthor(s): Ying Zhang, Bo Wang, Wanjun Jin, Yanan Wen, Lijing Nan, Mingming Yang, Rendan Liu, Yuyang Zhu, Chengjian Wang, Linjuan Huang, Xuezheng Song, Zhongfu Wang Sensitive glycomics analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is of great importance but significantly hampered by their low ionization efficiency and labile sialic acid moieties. Chemical derivatization offers a viable way to improve both the ionization efficiency and analytical sensitivity of the glycans in MS analysis by altering their hydrophobicity or charge property. Here we employed Girard’s reagent T (GT) for on-target derivatization (GTOD) of reducing glycan under mild acid condition to form stable hydrazones at room temperature, allowing rapid and sensitive identification of neutral and sialylated glycans in positive-ion mode as only permanently positive charged molecular ions without multiple ion adducts by MALDI-TOF-MS. The MS signal intensities of lactose, sialylated N-glycans derived from bovine fetuin and neutral N-glycans derived from RNaseB and ovalbumin were boosted by 7.44, 9.13, 12.96 and 13.47 folds on average (n=3), respectively. More importantly, after GTOD strategy, unwanted desialylation of sialylated glycans during MS was suppressed. The detection limit of the assay is desirable since the nanogram of N-glycans derived from 0.16 μg ovalbumin could be detected. The assay demonstrated good stability (RSD≤2.95%, within 10 days), reliable reproducibility (RSD=2.96%, n=7) and a desirable linear dynamic range from 78 nmol/mL to 10 μmol/mL. The strategy has been successfully applied to MS analysis of reducing glycans from human milks, neutral and sialylated O-, N-glycans from glycoproteins, and reducing glycans derived from glycosphingolipids, presenting neater [M]+ signals which allow detection of more low-abundance glycans and assignation of Neu5Ac vs. Neu5Gc or fucose vs. hexose in glycans due to the absence of the ambiguous interpretation from multiple peaks (ion adducts [M+Na]+ and [M+K]+). Moreover, the GTOD assay prevents desialylation during MALDI-TOF-MS profiling and enables distinct linkage-specific characterization of terminal sialic acids of N-glycans derived from human serum protein when combines with an esterification.Graphical abstractImage 1
  • Array of multifunctional polymers for localized immobilization of
           biomolecules on microarray substrates
    • Abstract: Publication date: Available online 9 October 2018Source: Analytica Chimica ActaAuthor(s): Laura Sola, Francesco Damin, Marcella Chiari The performance of microarray assays results from the optimization of several parameters: in particular, the physical-chemical properties of the surface play a pivotal role in determining the robustness of the technology. Usually, microarray substrates are entirely modified with coatings able to bind, covalently or not, bioprobes. Here we present a new, fully automated approach for the immobilization of biomolecules, based on the deposition of pL amounts of water solutions of DMA based copolymers on an uncoated surface, followed by the deposition, on the same spot, of the probe. Starting from a common precursor, polymers with different characteristics and functionalities are obtained by post-polymerization modification and by combining different monomers during the synthesis. This strategy, allows to functionalize and tailor the surface properties of discrete areas of the same array with different chemistries, that coexist on a single substrate. As a consequence, probes with different functionalities are bound simultaneously to neutral, positively, negatively charged, hydrophobic, hydrophilic polymers, in micrometer-sized spots. The proposed polymer array, applicable to both DNA or protein, offers advantages in terms of time and costs reduction, since pretreatment and coating steps are totally avoided, and the requested polymer amount is extremely low. Moreover, it provides a strategy perfectly suitable for miniaturization applicable to integrated biosensors or Lab-on-a-chip devices.Graphical abstractAll in one: a new strategy to functionalize and tailor the surface properties of localized areas of the same array with several chemistries is achieved by depositing pL solutions of DMA based copolymers on a single untreated and uncoated substrate. Probes (DNA or protein) with different functionalities are bound simultaneously to polymers with different characteristics, in micrometer-sized spots.Image 1
  • Simple and sensitive fluorescence sensor for methotrexate detection based
           on the inner filter effect of N, S co-doped carbon quantum dots
    • Abstract: Publication date: Available online 8 October 2018Source: Analytica Chimica ActaAuthor(s): Yanan Zhao, Shiying Zou, Danqun Huo, Changjun Hou, Mei Yang, Junjie Li, Minghong Bian Reliable and simple detection methods for chemotherapeutic agent contaminants, such as methotrexate, are required to minimize their possible toxic threat. However, detecting them remains a challenging in environmental and biological analysis. Here, we developed a fluorescent N, S co-doped carbon quantum dots (N, S co-doped CQDs) probe to detect methotrexate on the basis of the inner filter effect of fluorescence. Under optimized conditions, the fluorescent probe exhibits high sensitivity and specific selectivity with a linear detection range from 0.4 μg/mL to 41.3 μg/mL and a low detection limit of 12 ng/mL (S/N=3). Further, this N, S co-doped CQDs fluorescent probe can be used to analyze extracellular fluids and wastewater samples satisfactorily, thereby showing a remarkable potential for broad applications in biological molecule determination and environmental analysis.Graphical abstractA simple and sensitive fluorescence sensor was constructed based on the inner filter effect of N, S co-doped carbon dots for methotrexate detection.Image 1
  • Study of the gas-phase decomposition of multiply lithiated
           polycaprolactone, polytetrahydrofurane and their copolymer by two
           different activation methods: Collision-induced Dissociation and Electron
           Transfer Dissociation
    • Abstract: Publication date: Available online 5 October 2018Source: Analytica Chimica ActaAuthor(s): Kevin Prian, Inès Aloui, Véronique Legros, William BuchmannABSTRACTCollision-Induced Dissociation and Electron-Transfer Dissociation experiments were carried out from various lithium adducts ([M+2Li]2+, [M+3Li]3+) from polycaprolactone diol (pCL), polytetrahydrofurane (pTHF), and one triblock copolymer (pCL-pTHF-pCL).In both cases (pCL and pTHF), CID of triply-lithiated precursors led to complex mass spectra compared to corresponding ETD spectra, which remained relatively simple because CID product ions exhibit multiple charge states whereas ETD mainly led to singly-charged fragment ions. CID of pCL involves charge-remote rearrangements over the ester groups and intramolecular transesterification reactions, whereas ETD leads to radical and charge induced cleavages leading globally to structurally different product ions but accounting for the same bond cleavages: (CO)O-C and (CO)-O respectively. Both CID and ETD can produce a low amount of undesirable reactions such as consecutive fragmentations especially from 3+ precursors but these fragmentations are absent in ETD from 2+ species. CID of a triply-lithiated pTHF involved charge-induced and charge-remote fragmentations. In contrast, under ETD conditions, in the absence of suitable chemical functionality, pTHF did not undergo any backbone fragmentations at all. Nevertheless, proton abstraction by the fluoranthene reagent anion allowed the formation of species that could further be collisionally activated, leading to a depolymerization process from the ends. This strategy combining sequentially ETD and CID led to dramatically simplified product ion spectra. Concerning the supposed triblock copolymer, which was commercially purchased, both CID and ETD led to the same conclusion that at least a part of the copolymer was a diblock rather a triblock.Graphical abstractImage 1
  • Target-driven switch-on fluorescence aptasensor for trace aflatoxin B1
           determination based on highly fluorescent ternary CdZnTe quantum dots
    • Abstract: Publication date: Available online 5 October 2018Source: Analytica Chimica ActaAuthor(s): Xiaoting Lu, Chengquan Wang, Jing Qian, Chanchan Ren, Keqi An, Kun Wang Development of sensitive methods for trace aflatoxin B1 (AFB1) determination is of great significance due to its high toxicity and carcinogenicity. Herein, 3-mercaptopropionic acid (MPA)-capped ternary CdZnTe quantum dots (QDs) have been prepared via a simple hydrothermal route. We found that they exhibited enhanced intensity when benchmarked against their binary counterpart CdTe QDs. On this basis, a target-driven switch-on fluorescence aptasensor for trace AFB1 determination by employing the fluorescence resonance energy transfer (FRET) between the CdZnTe QDs and Au nanoparticles (AuNPs) pair. In the detection diagram, amino group-functionalized aptamers against AFB1 were firstly labelled with the CdZnTe QDs donors coated on silica nanospheres while the AuNPs acceptors were bioconjugated with the thiol group-modified complementary DNA (cDNA) of aptamer. By taking advantage of the DNA hybridization of aptamer and cDNA, the CdZnTe QDs (energy donor) and AuNPs (energy acceptor) were brought into close proximity, thereby leading to the occurrence of FRET during the aptasensor fabrication. When the aptasensor was incubated with AFB1, the specific binding between aptamer and target resulted in the detachment of AuNPs acceptors. This behavior would disturb the FRET process and led to the subsequent fluorescence recovery of CdZnTe QDs. Such designed aptasensor showed an increased fluorescence recovery upon the increasing concentration of AFB1 over a broad range of 50 pg mL–1 – 100 ng mL–1 and succeeded in spiked peanut samples. The proposed aptasensor is separation-free and easy-to-use, which might open up new possibilities in aptasensor fabrication by employing the novel CdZnTe QDs-AuNPs pair.Graphical abstractImage 1
  • Rolling Circle Amplification Integrated with Suspension Bead Array for
           Ultrasensitive Multiplex Immunodetection of Tumor Markers
    • Abstract: Publication date: Available online 4 October 2018Source: Analytica Chimica ActaAuthor(s): Gao Min, Lian Hong, Yu Longjiao, Gong Manfei, Ma Ling, Zhou Yingxing, Yu Muxin, Yan XiaomeiABSTRACTMultiplex detection of ultra-low abundant tumor markers is extremely important for early diagnosis and therapy evaluation. Herein, an ultrasensitive multiplex immunoassay was developed by combination of rolling circle amplification (RCA) and suspension bead array (SBA) technology. Based on a conventional sandwich-type immunoreaction on beads, the detection antibodies were conjugated with DNA primers, so RCA could be implemented to generate long-stranded DNA with abundant repeated sequences allowing for hybridization with fluorochrome-labeled oligonucleotide probes. Thus the fluorescence signal of immunocomplexes on the encoded beads can be greatly enhanced. Using the as-developed immuno-RCA suspension bead array (iRCA-SBA), simultaneous analysis of multiple tumor markers was achieved with the limits of detection of 3.1 pg/mL (∼0.1 pM) for prostate specific antigen (PSA), 9.1 pg/mL (∼50 fM) for carcinoembryonic antigen (CEA), and 0.66 pg/mL (∼9 fM) for α-fetoprotein (AFP), which are two to three orders of magnitude lower than those obtained by the conventional SBA method. The dynamic range were 4.5, 4.7, and 5.5 orders of magnitude for PSA, CEA, and AFP, respectively. Tests on clinical serum samples demonstrate that the tumor marker concentrations measured by the newly developed iRCA-SBA assay agreed well with those obtained by the conventional SBA method. These results indicate that the iRCA-SBA assay significantly increased the detection sensitivity and dynamic range without sacrificing the reliability and accuracy of conventional SBA. Upon the integration with iRCA, SBA could find more applications in the detection of low abundance protein biomarkers for early diagnosis of cancer and other diseases.Graphical abstractImage 1
  • Characterization and Sequencing of Lithium Cationized β-O-4 Lignin
           Oligomers using Higher-energy Collisional Dissociation Mass Spectrometry
    • Abstract: Publication date: Available online 3 October 2018Source: Analytica Chimica ActaAuthor(s): Shardrack O. Asare, Fan Huang, Bert C. Lynn The prospect of developing new bio-based products from lignin partially depends on the development of effective analytical techniques to characterize the end products from lignin degradation experiments. To date, the most utilized mass spectrometric technique for characterizing lignin oligomers has been negative ion mass spectrometry. Positive ion mass spectrometry remains a relatively unexplored approach for lignin sequencing. Here we report on the sequencing of lignin oligomers using lithium cationization positive ion electrospray followed by higher-energy collisional dissociation (HCD) tandem mass spectrometry on a high-resolution accurate-mass Orbitrap mass spectrometer. Thirteen synthetic lignin model oligomers containing β-O-4 and 4-O-α linkages were analyzed and sequenced based on their HCD tandem mass spectrometry fragmentation patterns. Proposed sequence-specific fragmentation pathways are provided. The method presented in this study provides a potential application of lithium cationization tandem mass spectrometry for the analysis of lignin degradation products.Graphical abstractImage 1
  • Stabilization and isotachophoresis of unmodified gold nanoparticles in
           capillary electrophoresis
    • Abstract: Publication date: Available online 2 October 2018Source: Analytica Chimica ActaAuthor(s): Szymon Dziomba, Krzesimir Ciura, Bruna Correia, Bartosz Wielgomas Capillary zone electrophoresis (CZE) of gold nanoparticles (Au NPs) was investigated in terms of dispersion stability during the analysis process. It was shown that CZE of Au NPs can be performed under dynamic coating conditions depending on the background electrolyte (BGE) composition. The influence of both the co-ion and counter-ion in the BGE was evaluated. It was proven that the application of relatively large buffering counter-ions provides steric stability to NPs during CZE. Among the investigated co-ions, citrate and MOPS were found to be advantageous for the CZE of Au NPs. On the other hand, the presence of zwitterionic substances and multiply charged counter-ions in BGE was shown to promote the aggregation and adsorption of the NPs to the capillary wall. A correlation between the particle stability in CZE and isotachophoresis (ITP) performance was observed and discussed. A sensitivity improvement by two orders of magnitude was achieved using the developed ITP methods.Graphical abstractImage 1
  • Derivatization reagent-assisted enantioseparation of 3-hydroxyaspartate
           with two chiral centers in rat cerebrospinal fluid by capillary
           electrophoresis-mass spectrometry
    • Abstract: Publication date: Available online 1 October 2018Source: Analytica Chimica ActaAuthor(s): Mingxia Liu, Hong Zhao, Zhiguo Zhang, Xiangjun Li, Lanqun Mao, Ruiping Zhang, Yuekui Wang A new analytical method based on capillary zone electrophoresis-mass spectrometry (CZE-MS) was proposed and validated for the simultaneous determination of four stereoisomers of 3-hydroxyaspartate with two chiral centers in rat cerebrospinal fluid (CSF) in absence of optically pure single enantiomer standards. The derivatization reagent 9-fluorenylmethyl chloroformate (FMOC-Cl) was found to assist chiral separation and the derivatized enantiomers of 3-hydroxyaspartate can achieve enantioseparation with a lower concentration (6 mM) of β-cyclodextrin (β-CD), while underivatized 3-hydroxyaspartate cannot be separated. The enhanced interactions between derivatized analytes and β-CD were demonstrated by proton nuclear magnetic resonance (1H NMR). The four stereoisomers of FMOC-3-hydroxyaspartate were identified successfully using a new method based on experimental and calculated electronic circular dichroism (ECD) spectra combined with the comparison of CE peak areas. Large volume sample stacking with polarity switching (LVSS-PS) was used to increase sensitivity and the detection limit of 356 nM was achieved for L-THA, which was around 10-fold improvement compared to the normal CE-MS analysis. The composition of the background electrolyte (BGE) was optimized by response surface methodology (RSM). Under the optimal conditions, satisfactory results of L-THA were obtained in terms of linearity over the range of 2-80 μM (R2>0.99) and precision (RSD below 1.43% and 2.56% for migration time and peak area, respectively). The recoveries for all four stereoisomers in spiked rat CSF ranged from 91.2% to 99.5%. The method has been successfully applied to rat CSF analysis and D-threo-3-hydroxyaspartate (D-EHA) was detected.Graphical abstractImage 1
  • Photoelectrochemical DNA biosensor based on g-C3N4/MoS2 2D/2D
           heterojunction electrode matrix and co-sensitization amplification with
           CdSe QDs for the sensitive detection of ssDNA
    • Abstract: Publication date: Available online 1 October 2018Source: Analytica Chimica ActaAuthor(s): Pan-Pan Li, Xing-Pei Liu, Chang-Jie Mao, Bao-Kang Jin, Jun-Jie Zhu A novel enhanced photoelectrochemical (PEC) DNA biosensor, based on a compact heterojunction g-C3N4/MoS2 and co-sensitization effect with CdSe quantum dots (QDs), was first proposed for simple and accurate analysis of a short ssDNA. In this work, the g-C3N4/MoS2 was successfully synthesized and used as the electrode matrix material to construct PEC biosensor for the first time. As expected, 2D/2D heterojunction was formed between g-C3N4 and MoS2, which could promote the separation of photogenerated electron-hole pairs resulting in an enhanced photocurrent. In the present of target DNA, the CdSe QDs labeled reporter DNA was complementary pairing with target DNA which was specific recognized by capture DNA loading on self-assembled CdS QDs film, leading to close contact between CdSe QDs and g-C3N4/MoS2 modified electrode surface, thereby resulting in the enhance photocurrent intensity due to the co-sensitization effect. Under the optimal operating conditions, the photoelectrochemical biosensor demonstrated favorable accuracy and could responds to 0.32 pM (S/N=3) with a linear concentration ranging from 1.0 pM to 2.0 μM. Moreover, the proposed PEC DNA biosensor exhibits high sensitivity, excellent specificity, acceptable reproducibility and accuracy, showing a promising potential in DNA bioanalysis and other relative fields.Graphical abstractA novel enhanced photoelectrochemical DNA biosensor, based on a compact heterojunction g-C3N4/MoS2 and co-sensitization effect with CdSe QDs, was proposed for analysis of a short ssDNA.Image 1
  • Isotope Tracing Assisted Metabolic Profiling: Application to Understanding
           HSP60 Silencing Mediated Tumor Progression
    • Abstract: Publication date: Available online 1 October 2018Source: Analytica Chimica ActaAuthor(s): Haiping Tang, Ruifang Teng, Xinyuan Zhao, Xueying Wang, Lina Xu, Haiteng Deng, Xiaohui Liu Isotope-tracing facilitates the understanding of metabolic regulation in biological systems. Depending on the selection of tracers, some essential metabolites cannot be traced. A comprehensive understanding of the regulated pathways can only be achieved with focus beyond labeled metabolites. The isotope tracing assisted metabolic profiling described here is a platform for high throughput mapping of isotope labeled metabolites with simultaneous metabolomics profiling. This approach incorporates an in-house MS/MS library for metabolite identification and ID-based quantitation. An “Isotopic” software was developed to generate potential labeled isotopomers. Using this platform, a total of 394 metabolites were reliably identified based on MS/MS confirmation in 3 million 293T cells, among which 54 and 43 metabolites were discovered to carry extensive labels (>2%) from 13C6-glucose and 13C5-glutamine respectively. Citrate flowing into malate shuttle was also observed. More interestingly, the rate-limiting step in NAD and UDP-GlcNAc biosynthesis was clearly observed according to time course labeling. In HSP60 knockdown cell lines, enhanced purine and pyrimidine biosynthesis were confirmed by the abundance and labeling percentages of intermediate metabolites.Graphical abstractImage 1
  • Quantification of the soluble Receptor of Advanced Glycation End-Products
           (sRAGE) by LC-MS after enrichment by strong cation exchange (SCX)
           solid-phase extraction (SPE) at the protein level
    • Abstract: Publication date: Available online 29 September 2018Source: Analytica Chimica ActaAuthor(s): Frank Klont, Marc R. Joosten, Nick H.T. Ten Hacken, Péter Horvatovich, Rainer Bischoff The study of low abundant proteins contributes to increasing our knowledge about (patho)physiological processes and may lead to the identification and clinical application of disease markers. However, studying these proteins is challenging as high-abundant proteins complicate their analysis. Antibodies are often used to enrich proteins from biological matrices prior to their analysis, though antibody-free approaches have been described for some proteins as well. Here we report an antibody-free workflow on the basis of strong cation exchange (SCX) enrichment and liquid chromatography-mass spectrometry (LC-MS) for quantification of the soluble Receptor of Advanced Glycation End-products (sRAGE), a promising biomarker in chronic obstructive pulmonary disease (COPD). sRAGE was quantified in serum at clinically relevant low to sub ng mL−1 levels. The method was validated according to U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) guidelines and was compared to an antibody-based LC-MS sRAGE method. The SCX-based method builds upon the bipolar charge distribution of sRAGE, which has a highly basic N-terminal part and an acidic C-terminal part resulting in an overall neutral isoelectric point (pI). The highly basic N-terminal part (pIcalculated = 10.3) allowed for sRAGE to be enriched by SCX at pH 10, a pH at which most serum proteins do not bind. This study shows that ion exchange-based enrichment is a viable approach for the LC-MS analysis of several low abundant proteins following a thorough analysis of their physical-chemical properties.Graphical abstractImage 1
  • Determination of Se(IV) concentration via cathodic stripping voltammetry
           in the presence of Cu(II) ions and ammonium diethyl dithiophosphate
    • Abstract: Publication date: Available online 28 September 2018Source: Analytica Chimica ActaAuthor(s): Ignacio E. Merino, Edgardo Stegmann, Margarita E. Aliaga, Marisol Gomez, Verónica Arancibia, Carlos Rojas−Romo The development of a methodology for the determination of Se(IV) concentration via cathodic stripping voltammetry is described in this work. The methodology is based on the formation of copper selenide (Cu2Se), whose reduction signal at –0.60 V has been used as an analytical response to quantify the Se(IV) concentration in solution. The novelty of our methodology is the study of this system in the presence of a ligand such as ammonium diethyl dithiophosphate (ADTTP), which forms complexes with Cu(II) and Se(IV). The results showed that the presence of ADTTP plays an important role, increasing the sensitivity of the determination by almost a factor of two compared with the methodology in the absence of the ligand. The optimized conditions were pH 1.6 (phosphoric acid, 2.0 x 10–2 mol L–1), CCu(II) = 1.5 mg L−1, CADTTP = 2.0 μmol L−1, Eacc = −0.4 V and tacc = 45 s. The detection and the quantification limits obtained were 0.065 and 0.21 μg L–1, respectively, and linearity was maintained up to 4.0 μg L–1 of Se(IV). The sensitivity was 10.26 nA L μg−1. On the other hand, the relative standard deviation for 15 replicate measurements at 1.0 μg L−1 of Se(IV) was 1.6%. The usefulness of the method was evaluated by determining Se(IV) in two certified reference materials (TMDW and TM−28.4) with relative errors of less than 2.0%. The proposed method was successfully applied to the determination of Se(IV) in spiked tap water and in a liquid pharmaceutical formulation with satisfactory results.The developed methodology presents a low detection limit, good repeatability, selectivity and linear range. Furthermore, the sensibility of the method was achieved by applying a short accumulation time (45 s).Graphical abstractImage 1
  • Collision cross section (CCS) as a complementary parameter to characterize
           human and veterinary drugs
    • Abstract: Publication date: Available online 28 September 2018Source: Analytica Chimica ActaAuthor(s): Carmen Tejada-Casado, Maykel Hernández-Mesa, Fabrice Monteau, Francisco J. Lara, Monsalud del Olmo-Iruela, Ana M. García-Campaña, Bruno Le Bizec, Gaud Dervilly-PinelABSTRACTIn the context of human and veterinary drugs identification, ion mobility spectrometry (IMS) in combination with mass spectrometry (MS) may provide a relevant complementary piece of information to mass-to-charge ratio (m/z), the so-called collision-cross-section (CCS). Up to now, however, the application of CCS as identification parameter has not been fully investigated due to the reduced number of these drugs that have being characterized in terms of CCS. This work proposes a CCS database for 92 human and veterinary drugs, including eighteen benzimidazoles, eleven 5-nitroimidazoles, eleven aminoglycosides, nineteen quinolones, eighteen β-lactams, ten sulfonamides and five tetracyclines. Among them, 37 drugs have been characterized in terms of CCS for the first time. The CCS values of the other 55 compounds have been compared with those from a recently published database in order to evaluate inter-laboratory reproducibility, which is crucial for the implementation of the CCS as identification parameter. CCS values were measured by traveling wave ion mobility spectrometry (TWIMS) under positive ionization conditions. Nitrogen was used as drift gas in the ion mobility cell. The proposed database covers 173 ions including [M+H]+ and [M+Na]+ species. High correlation between m/z and CCS has been observed for [M+H]+ (R2 = 0.9518, n = 91) and [M+Na]+ (R2 = 0.9135, n = 82) ions. As expected, CCS values for sodium adducts are generally greater than for protonated molecules because they exhibit higher molecular weight. However, sodium adducts of aminoglycosides, β-lactams, and of several quinolones and benzimidazoles, were characterized as more compact ions than their related protonated molecule. In addition, this work describes the fragmentation pattern observed for the studied molecules. For the first time, the main fragment ions for most of the compounds have also been characterized in terms of CCS, involving a total of 238 ions. As proof of concept, for the application of this database to biological matrices, eleven veterinary drugs in bovine urine samples were characterized in terms of CCS, showing that this parameter was not influenced by the matrix.Graphical abstractImage 1
  • Bimetallic cerium/copper organic framework-derived cerium and copper
           oxides embedded by mesoporous carbon: Label-free aptasensor for
           ultrasensitive tobramycin detection
    • Abstract: Publication date: Available online 28 September 2018Source: Analytica Chimica ActaAuthor(s): Shijun Wang, Zhenzhen Li, Fenghe Duan, Bin Hu, Linghao He, Minghua Wang, Nan Zhou, Qiaojuan Jia, Zhihong Zhang We reported a novel bimetallic cerium/copper-based metal organic framework (Ce/Cu-MOF) and its derivatives pyrolyzed at different temperatures, followed by exploiting them as the scaffold of electrochemical aptamer sensors for extremely sensitive detection of trace tobramycin (TOB) in human serum and milk. After the calcination at high temperature, the meal coordination centers (Ce and Cu) were transferred to metal oxides containing various chemical valences, such as Ce(III), Ce(IV), Cu(II) and Cu(0), which were embedded within the mesoporous carbon network originated from the organic ligands (represented by CeO2/CuOx@mC). Owning to the strong synergistic effect among the metal oxides, mesoporous carbon, and small cavities and open channels of MOF, the as-prepared CeO2/CuOx@mC nanocomposites not only possess good electrochemical activity but also exhibit strong bioaffinity toward the aptamer strands. By comparing the electrochemical biosensing peroformances using on the Ce/Cu-MOF- and the series of CeO2/CuOx@mC-based aptasensors, the constructed CeO2/CuOx@mC900-based (calcinated at 900 °C) aptasensor exhibits an extremely low detection limit of 2.0 fg mL−1 within a broad linear TOB concentration range from 0.01 pg mL−1 to 10 ng mg L−1. It demonstrates that the proposed aptasensor is substantially superior to those previously reported in the literature, along with high selectivity, good stability and reproducibility, and acceptable applicability in human serum and milk. Thereby, the newly fabricated aptasensing approach based on bimetallic CeO2/CuOx@mC has a considerable potential for the quantitative detection of antibiotics in the food safety and biomedical field.Graphical abstractImage 1
  • An ultrasensitive label free human papilloma virus DNA biosensor using
           gold nanotubes based on nanoporous polycarbonate in electrical alignment
    • Abstract: Publication date: Available online 28 September 2018Source: Analytica Chimica ActaAuthor(s): Mohsen Shariati, Mohammad Ghorbani, Pezhman Sasanpour, Ali Karimizefreh An impedimetric human papilloma virus (HPV) DNA biosensor based on gold nanotubes (AuNTs) in label free detection was materialized. The AuNTs decorated nanoporous polycarbonate (AuNTs-PC) template as biosensor electrode was fabricated by electrodeposition method. The single strand DNA (ss-DNA) probe was covalently immobilized onto the AuNTs-PC electrode. The hybridization of target sequences with the ss-DNA probe was observed by the electrochemical impedance spectroscopy (EIS). The biosensor showed high selectivity and could differentiate between the complementary, mismatch and non-complementary DNA sequences. The EIS measurements were matched to Randle's equivalent circuit. The negatively-charged HPV DNA oligonucleotides under external electric field were oriented in a preferred direction and the bio-sensing responses were intensified by controlling the immobilization and hybridization of the sequences on the AuNTs surface. The fabricated DNA biosensor under electric field amplification was stable up to six weeks and demonstrated 97% of its initial detection responses. The biosensor displayed the HPV DNA hybridization detection in very low concentrations in the linear response ranges of 0.01 pM–1 μM and was able to acquire a limit of detection (LOD) of 1 fM.Graphical abstractImage 1
  • Sol-gel preparation of titanium (IV)-immobilized hierarchically porous
           organosilica hybrid monoliths
    • Abstract: Publication date: Available online 28 September 2018Source: Analytica Chimica ActaAuthor(s): Haiyang Zhang, Xiaowei Li, Yating Yao, Shujuan Ma, Zhen Liu, Junjie Ou, Yinmao Wei, Mingliang Ye Hierarchically porous monoliths as a key feature of biological materials have been applied in enrichment and separation. In this work, a metal immobilized hierarchically porous organosilica hybrid monolith was synthesized by hydrolysis and condensation of tetraethoxysilane (TEOS) and diethoxyphosphorylethyl-triethoxysilane (DPTS) under alkaline environment. Phosphonate ester groups were firstly introduced by the employment of DPTS as functional monomer, and then acidified to phosphonic acids. The surface area of optimal monolith could reach to 1170 m2/g, which simultaneously contained micropores and mesopores (4 nm) obtained from nitrogen sorption measurement. Meanwhile, mercury intrusion porosimetry (MIP) further demonstrated that macropores (1–3 μm) existed in monoliths. Followed by chelating with titanium ion (Ti4+), the hierarchically porous organosilica hybrid monoliths could be applied as IMAC materials. This synthesized process was easy-operating and time-saving, and avoided the tedious and complex process of traditional Ti4+-IMAC materials. Furthermore, the Ti4+-IMAC monoliths exhibited high adsorption capacity for pyridoxal 5′-phosphate (82.6 mg/g). The 3282 unique phosphopeptides could be identified from 100 μg of HeLa digests after enrichment with the monolith, exhibiting excellent enrichment performance of low-abundance phosphopeptides.Graphical abstractImage 1
  • Solid-phase microextraction of antibiotics from fish muscle by using
           MIL-101(Cr)NH2-polyacrylonitrile fiber and their identification by liquid
           chromatography-tandem mass spectrometry
    • Abstract: Publication date: Available online 28 September 2018Source: Analytica Chimica ActaAuthor(s): Sandip Mondal, Jianqiao Xu, Guosheng Chen, Siming Huang, Chuyu Huang, Li Yin, Gangfeng Ouyang Antibiotics are a group of antibacterial drugs used in the treatment and prevention of bacterial diseases in humans, veterinary animals, and farmed fish. Inappropriate and excessive use of antibiotic therapy leads to antibiotic fragment in the water bodies thus affect the aquatic organisms. In this study, an amino group modified high surface area metal-organic framework (MOF) MIL-101(Cr)-NH2 was used to prepare solid-phase microextraction (SPME) fiber to detect four different classes (total 6 ABs) of antibiotics for the first time from living tilapia fish (Oreochromis mossambicus) by coupling SPME with high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The extraction efficiencies of the custom-made fiber were superior as compared with the commercial C18, polydimethylsiloxane (PDMS), PDMS/divinylbenzene (DVB) and polyacrylate fibers. The custom-made fiber also exhibited excellent reproducibility with the low intra-fiber relative standard deviations (RSDs 1.5%–8.3%) and inter-fiber RSDs (7.3%–14.5%), which made it ideal for in vivo extraction in fish muscle. The as-prepared MIL-101(Cr)-NH2 fiber was then used to determine antibiotics in the dorsal-epaxial muscle of living fish. Comparing to the traditional solid-liquid extraction (SLE) method, the SPME method showed reduced invasiveness and higher sensitivity than the SLE method. In general, this study explored a convenient, cost-effective and highly sensitive SPME method based on amino modified MOF for in vivo antibiotic detection in fish muscle.Graphical abstractImage 1
  • Controlled microwave derivatization reaction for reproducible trace
           analysis of budesonide in human plasma
    • Abstract: Publication date: Available online 26 September 2018Source: Analytica Chimica ActaAuthor(s): Sameh Ahmed, Noha N. Atia Microwave reactors with on-line controlled reaction conditions have been recently innovated to improve reaction kinetics and reproducibility. Herein, a modern microwave reactor was dedicated to develop a new, sensitive and reproducible approach for trace analysis of budesonide (BUD) in human plasma. The method was based on fast microwave reaction of BUD with dansyl hydrazine (DNS-HZ) reagent under controlled conditions coupled with high-performance liquid chromatography (HPLC)-fluorescence detection. The microwave irradiation and dansylation conditions were optimized for the best sensitivity and selectivity. The controlled microwave derivatization reaction (CMDR) decreased the reaction time, amplified the reaction yield and enhanced product purities by reducing the unwanted side reactions. The chromatographic separation was attained by isocratic elution on reversed phase column via a mobile phase consisted of methanol and phosphate buffer (10 mM, pH 7.0) at ratio 80:20 (v/v). The fluorescence detector was set at 500 nm after excitation at 330 nm. Betamethasone dipropionate (BDP) was used as an internal standard. CMDR-HPLC method validation was performed in agreement with bioanalytical method validation guidelines by the US food and drug administration (US-FDA). The obtained linearity range was 0.2-100 ng mL-1 with correlation coefficient 0.9991 and the lower limit of quantitation (LLOQ) in human plasma was 0.21 ng mL-1. The developed CMDR -HPLC method was applied successfully for assessment of plasma levels of BUD in allergic rhinitis patients after intranasal administration of the micronized BUD.Graphical abstractImage 1
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