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Showing 1 - 200 of 3161 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: 35, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 24, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 96, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 27, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 37, 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: 414, 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: 259, 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: 3, 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: 7)
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: 17, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 8, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 10, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 23)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 159, 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: 15, 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: 24, 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: 33, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, 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: 4)
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: 9, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 26, 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: 8)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 46, 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: 59, 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: 23, 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: 23)
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: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 18, 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: 7, 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: 23)
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: 2)
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: 12)
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: 10)
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: 19)
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: 64)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (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: 403, 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: 11, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 34, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 18)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 14)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 47, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 349, 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: 456, 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: 4)
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: 12, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 11)
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: 10, 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: 10, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 51, 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: 53, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 56, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 44, 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: 29, 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: 47)
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: 221, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 66, 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: 63, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 18, 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: 42, SJR: 1.512, CiteScore: 5)
Analytical Biochemistry     Hybrid Journal   (Followers: 183, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 12, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 12)
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: 204, 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: 42  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0003-2670 - ISSN (Online) 1873-4324
Published by Elsevier Homepage  [3157 journals]
  • Inverted mirror image molecular beacon-based three concatenated logic
           gates to detect p53 tumor suppressor gene
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Chang Xue, Shuai Xiao, Chang-He Ouyang, Cong-Cong Li, Zhi-Hua Gao, Zhi-Fa Shen, Zai-Sheng Wu Mutation of p53 tumor suppressor gene represents one of the early molecular events in tumor initiation and progression. Although molecular computing holds tremendous potential with important applications in diagnosis, prognosis and treatment of human diseases at the molecular level, designing molecular logic gates to implement cascade amplification via operating autonomously for the detection of point mutations still remains challenging. In this contribution, we developed a three concatenated logic gates (TCLG) to perform multiple strand displacement amplification (m-SDA) for screening the cancer-related point mutations only via designing an innovative molecular beacon (MB). Specifically, using p53 gene as model target, extending the two ends of a MB via adding two fragments with the same sequence achieves two unique terminal single-stranded (ss) overhangs. After self-folding of MB into hairpin structure, the two overhangs exhibit a near inverted mirror image (IM) relationship if taking the base nature and direction into account. For this, the probe is called IM-MB. Because cascade SDAs can occur on IM-MB and promote each other, the target gene can be detected down to 10 pM. Along this line, the TCLG circuit was proposed, and two primers and target gene serve as the indispensable input signals. Utilizing this logic circuit, the point mutation or absence of target gene can be sensitively screened. Moreover, its potential application in the recognition of point mutations in complex biomatrix has been demonstrated via blind test. The proof-of-concept scheme is expected to provide new insight into the development of DNA-based molecular logic gates and their applications in basic research, medical diagnosis and precise treatment and treatment of genetic diseases.Graphical abstractImage 1
  • A novel isolongifolanone based fluorescent probe with super selectivity
           and sensitivity for hypochlorite and its application in bio-imaging
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Zhonglong Wang, Yan Zhang, Jie Song, Yiqin Yang, Xu Xu, Mingxin Li, Haijun Xu, Shifa Wang In this study, a novel biocompatible fluorescent probe (DN) capable of detecting ClO− in physiological medium was rationally designed and synthesized from natural and renewable isolongifolanone. This probe underwent a highly specific and sensitive oxidation reaction with ClO− and liberated an isolongifolanone derivative (PA) emitting intensive blue fluorescence. In response to ClO−, the fluorescence emission of DN was obviously enhanced within a short time. The detection limit of DN toward ClO− was found to be as low as 5.86 × 10−9 M. IR, MS and DFT calculation were employed to further confirm the sensing mechanism. Moreover, the test strips coated with DN could easily recognize ClO− from other relevant species through the changes of fluorescence color under 365 nm UV lamp. More importantly, we also successfully demonstrated the potential application of DN for the detection of intracellular hypochloritein living cells.Graphical abstractThe probe DN exhibited excellent selectivity and sensitivity towards ClO−, and it was successfully used for fluorescence imaging of ClO− in living cells.Image 1
  • Phenanthroline-linked berberine dimer and fluorophore-tagged DNA conjugate
           for the selective detection of microRNA-185: Experimental and molecular
           docking studies
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Xiang-Ming Hu, Rong-Tian Li, Miao-Miao Zhang, Ke-Yang Wu, Huan-Huan Li, Nai-Han Huang, Bin Sun, Jin-Xiang Chen A phenanthroline (phen) tethered berberine dimer 1 is synthesized and further conjugated with carboxyfluorescein (FAM)-labeled single-stranded probe DNA (P-DNA) to give P-DNA@1. The mutual interaction of these two components triggers the fluorescence quenching of FAM, and the non-emissive P-DNA@1, in turn, functions as a sensor to detect cancer-associated microRNA-185 (miRNA-185), characterized by the FAM fluorescence recovery. The results show that P-DNA@1 is capable of detecting miRNA-185 in 2 min with the detection limit of 0.2 nM. The detection mechanism was supported by fluorescence anisotropy, binding constant and molecular docking study. Competing experiments further indicate that P-DNA@1 exhibits a high selectivity for miRNA-185 thus has a good potential in the diagnosis of related cancer at the early stage.Graphical abstractImage 1
  • Fluorescent sensor array for discrimination of biothiols based on
           poly(thymine/cytosine)-templated copper nanoparticles
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Hongyan Xi, Xin Li, Qingyun Liu, Zhengbo Chen In medicine, the detection and identification of biothiols have received increasing attention due to their crucial roles in life activities. Hence, we present a facile, rapid, and effective method for identification of five kinds of biothiols including glutathione (GSH), l-cysteine (Cys), dithiothreitol (DTT), 2-mercaptoethanol (MCE), and 3-mercaptopropionic acid (MPA). The proposed sensor array is fabricated based on single-stranded poly (thymine/cytosine)-templated fluorescent copper nanoparticles (CuNPs), which are controlled through thymine-Hg2+-thymine (T-Hg2+-T) and cytosine-Ag+-cytosine (CAg+C) coordination. The results show that single-stranded poly T and poly C are used as a highly efficient template, and ascorbic acid acts as a reductant to form CuNPs. Owing to the different thiol binding affinity between Hg2+ (pKd = 3.90) and Ag+ (pKd = 5.50), the sensor array produces a unique pattern of fluorescence variations when it interacts with the five biothiols. Linear discriminant analysis (LDA) is applied to analyze the fluorescence pattern and generated a clustering map for a clear identification of the five biothiols. By employing this “turn-on” sensor array, five thiols were successfully discirminated at the 50 nM level in buffer solution and serum samples.Graphical abstractImage 1
  • Real-time cell analysis of the cytotoxicity of a pH-responsive
           drug-delivery matrix based on mesoporous silica materials functionalized
           with ferrocenecarboxylic acid
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Zhihui Xu, Ling Cai, Huijun Jiang, Yujie Wen, Luming Peng, Yuan Wu, Jin Chen During the past decade, accumulating studies have been conducted on the mesoporous silica materials as the matrix of controlled drug-delivery, in which the complicated post-synthesis procedures are often involved with the molecular design to achieve the efficacy. In this study, a simplified drug delivery system of anti-cancer drug of doxorubicin (DOX) based on mesoporous SBA-15 functionalized with ferrocenecarboxylic acid (FCA) was constructed. Through a combination of physicochemical characterizations, the presence of FCA that was anchored inside the pore wall of amine groups grafted SBA-15 exhibits electron-accessible behavior without affecting the intactness of composite material. The pH-responsive release of drug molecules was achieved through the conjugation of DOX with FCA in the interior channels of mesoporous composites, which also favors the more coverage of DOX. Furthermore, the real-time cell analysis was performed to monitor the release of DOX from the mesopores and resulting cytotoxicity of cancer cell of A549 was evaluated, which results in a calculated IC50 of 43.8 μg/ml (24 h). The constructed mesoporous FCA-SBA-15 composite material provides an integrated nanoplatform to exert controlled-delivery of anti-cancer drug molecules.Graphical abstractThe mesoporous silica material of Santa Barbara Amorphous-15 (SBA-15) grafted with ferrocenecarboxylic acids on the internal surface of channels for anticancer drug loading with pH-sensitive releasing characteristics.Image 1
  • Silver nanoparticles-based plasmonic assay for the determination of sugar
           content in food matrices
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Flavio Della Pelle, Annalisa Scroccarello, Simona Scarano, Dario Compagnone A simple colorimetric assay for sugars (monosaccharides, polyols and disaccharides) quantification based on silver nanoparticles (AgNPs) formation is proposed. Sugars are able to form AgNPs reducing Ag+ and stabilizing the suspension. Since the driving force is not only chemical reduction, the optimized assay allows the determination of both “reducing” and “non-reducing” sugars with similar reactivity. The localized surface plasmon resonance (LSPR) absorption band with maximum wavelength centered at ≈ 430 nm (A430) is used for the detection. Monosaccharides, disaccharides and polyols with different functional groups and structure have been investigated: D-(+)-glucose, D-(+)-galactose, D-(−)-fructose, sucrose, D-(+)-raffinose D-(+)-maltose, D-(+)-trehalose, D-mannitol, D-sorbitol, i-inositol, xylitol and D-(+)-xylose. The resulting AgNPs have been characterized by UV–Vis spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The reactivity of monomers and polyols was found higher than the disaccharides. The AgNPs-based method was applied to the determination of the sugars content in soft drinks (n = 6) and apple extracts (n = 5). Sugars content (expressed as glucose equivalents) determined by the proposed assay resulted comparable to results obtained by ion chromatography (R = 0.994). Reproducibility (RSD ≤ 9.4%) and recovery values (from 86.1% to 117.7%) in food matrices were satisfactory. Moreover, the assay is selective vs. potentially interfering compounds found in food. Considering the assay time (10 min), the low cost of reagents, limited volumes of sample (5–100 μL), no use of organic solvents and low waste generation, this assay appears very promising for sugars content determination.Graphical abstractImage 1
  • Design, preparation and evaluation of a high performance sensor for
           formaldehyde based on a novel hybride nonocomposite ZnWO3/rGO
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Muhammad Aqeel Ashraf, Zhenling Liu, Wanxi Peng, Zohreh Parsaee The ultrasound wave assisted synthesis of a novel ZnWO3/rGO hybrid nono composition (ZnWO3/rGO HNC) as a high performance sensor for formaldehyde (FA) has been reported. Different techniques of analysis such as XRD, FE-SEM, TGA, XPS, HRTEM and BET were applied for morphological and spectroscopic characterization of the ZnWO3/rGO HNC. The sensing evaluation of the constructed sensor showed high selectivity, sensitivity and a linear correlation between achieved responses and concentration of target gas (1–10 ppm) with R2 = 0.993 at temperature of 95 °C. The determination of FA was validated and performed using gas chromatography-mass spectrometry combined by solid phase micro-extraction after derivatization with O-(2,3,4,5,6-pentafluoro-benzyl)-hydroxylamine hydrochloride. Validation was carried out in terms of limit of detection linearity, precision, and recovery. The mechanistic evaluation of sensing behavior of the ZnWO3/rGO HNC was interpreted based on large specific surface area (SSA) to volume, mesoporous structure and the heterojunction between rGO and ZnWO3 at the interface between the rGO and ZnWO3.Graphical abstractImage 1
  • Construction and testing of an atmospheric-pressure transmission-mode
           matrix assisted laser desorption ionisation mass spectrometry imaging ion
           source with plasma ionisation enhancement
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Rory T. Steven, Michael Shaw, Alex Dexter, Teresa Murta, Felicia M. Green, Kenneth N. Robinson, Ian S. Gilmore, Zoltan Takats, Josephine Bunch Matrix assisted laser desorption ionisation mass spectrometry (MALDI-MS) at atmospheric pressure (AP) is, with a few notable exceptions, overshadowed by its vacuum based forms and AP transmission mode (TM) MALDI-MS lacks the up-take its potential benefits might suggest. The reasons for this are not fully understood and it is clear further development is required to realise the flexibility and power of this ionisation method and geometry. Here we report the build of a new AP-TM-MALDI-MSI ion source with plasma ionisation enhancement. This novel ion source is used to analyse a selection of increasingly complex systems from molecular standards to murine brain tissue sections. Significant enhancement of detected ion intensity is observed in both positive and negative ion mode in all systems, with up to 2000 fold increases observed for a range of tissue endogenous species. The substantial improvements conferred by the plasma enhancement are then employed to demonstrate the acquisition of proof of concept tissue images, with high quality spectra obtained down to 10 × 10 μm pixel size.Graphical abstractImage 1
  • Identification of very long-chain (>C24) fatty acid methyl esters using
           gas chromatography coupled to quadrupole/time-of-flight mass spectrometry
           with atmospheric pressure chemical ionization source
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): B. Garlito, T. Portolés, W.M.A. Niessen, J.C. Navarro, F. Hontoria, Ó. Monroig, I. Varó, R. Serrano Gas chromatography coupled to a quadrupole time-of-flight mass analyzer (QTOF) with an atmospheric pressure chemical ionization (APCI) source has been tested to study the ionization and mass spectrometric behavior of long-chain and very long-chain polyunsaturated fatty acids (LC-PUFAs, C18–24; VLC-PUFAs,>C24). The protonated molecule ([M+H]+), measured at accurate mass, became the base peak of the spectrum for all the studied compounds and was promoted by the addition of water into the source. This fact overcame the existing difficulties for the identification of VLC-PUFAs when using an electron ionization source (EI). The extensive fragmentation of PUFAs in this source is the main drawback due to the fact that since reference standards are not commercially available, final identification relies on retention time estimation. The application of GC−APCI-QTOF to the screening of lipid extracts from the eyes of different fish species added confidence to the identification of several VLC-PUFAs. Further investigation of ion ratios allowed to predict the position of key double bonds enabling the classification of VLC-PUFAs as ω3 or ω6 compounds. VLC-PUFAs spectra found in biological samples were compared to those obtained from corresponding peaks found in heterologous expression experiments of fish's Elovl4.Graphical abstractImage 1
  • Sieve-through vertical flow platform for efficient liquid exchange in
           particle-based assays
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Yi Zhang, Daniel Yoke San Lee, Aysha Farwin, Jackie Y. Ying Particle-based assays are widely used in many biomedical applications. However, the performance of particle-based systems is often compromised by the carry-over contamination caused by the residual reagents during the liquid-exchange process. We have developed a sieve-through platform that utilizes a porous membrane to sieve out the particles, and an absorbent pad to remove the waste liquid by capillary force. The porous membrane is able to contain the liquid in the reaction chamber, and allows the waste liquid to flow through when it is brought into contact with the absorbent pad. The sieve-through platform is able to effectively remove the waste liquid, thereby achieving a more efficient liquid exchange as compared to the conventional process, and minimizing the carry-over contamination. In this study, we have determined the factors that affect the flow characteristics through the porous membrane on the sieve-through platform. We have shown that the sieve-through platform effectively reduces the carry-over contamination. In addition, we have shown particle-based ELISA on the sieve-through platform for the analysis of proteins and cells. We have further demonstrated the potential of the sieve-through platform for high-throughput analysis by presenting a sieve-array, which allows concurrent analysis of multiple samples in parallel. The sieve-through platform can significantly improve the performance of particle-based systems.Graphical abstractImage 1
  • Effects of extraction method and storage of dry tissue on marine lipids
           and fatty acids
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Fany Sardenne, Nathalie Bodin, Luisa Metral, Anaïs Crottier, Fabienne Le Grand, Antoine Bideau, Blandine Brisset, Jérôme Bourjea, Claire Saraux, Sylvain Bonhommeau, Vincent Kerzérho, Serge Bernard, Tristan Rouyer Various protocols are currently used to study marine lipids, but there is a growing interest in working on dry samples that are easier to transport. However, reference protocols are still lacking for dry samples. In order to make recommendations on this use, lipid classes and fatty acids (FA) obtained from six analytical protocols using two different tissue states (dry vs wet) and three extraction methods (automat vs manual potter vs leaving the solvent to work on tissue) were compared. Three dry storage modes of tissue (freezer vs gas nitrogen vs dry room) during one and three months were also compared. These comparisons were made on seven marine species with different lipid profiles, including fishes, crustaceans and mollusks. Lipid classes and FA obtained from wet and dry tissues were similar, but they were affected by the extraction methods. Regardless of tissue state, “Leave to work” methods obtained the highest lipid quantities, followed by manual potter and automat methods (ca. 90% and 80% of “Leave to work” methods, respectively). Linear relationships allowed correction for lipid classes and FA concentrations obtained from different protocols. The repeatability of all protocols still needs to be improved, especially for fish species. Increasing the replicate number for each sample might be an indirect way to improve lipid quantification. Our results show that storing dry tissues in the freezer for more than one month was associated with a decrease in lipids, which is also observed for other storage methods. For qualitative studies of FA (expressed in %), a three-month storage of dry tissue in freezer did not affect the relative composition of species/tissues with a lipid content below 20% of dry weight.Graphical abstractImage 1
  • Stable isotope labeling derivatization and magnetic dispersive solid phase
           extraction coupled with UHPLC-MS/MS for the measurement of brain
           neurotransmitters in post-stroke depression rats administrated with
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Xian-En Zhao, Yongrui He, Shuyun Zhu, Yanqiu Xu, Jinmao You, Yu Bai, Huwei Liu Synchronous measurement of brain neurotransmitters and blood drug metabolism by dual sites in vivo microdialysis can provide very important information for several neurological disorders such as post-stroke depression (PSD). In this work, d0/d3-6-N-methyl-rhodamine 6G-N-hydroxysuccinimidyl formate (d0/d3-MRSF) were firstly designed, synthesized and used as stable isotope labeling derivatization reagents for the determination of multiple neurotransmitters by ultra-high performance liquid chromatography-tandem mass spectrometry. The light d0-MRSF was used to label neurotransmitters in real samples and the heavy d3-MRSF was used to label standards, which served as internal standards for quantification to minimize matrix effect. The d0/d3-MRSF-neurotransmitter derivatives were easily adsorbed onto the surface of Fe3O4@graphene oxide. Magnetic dispersive solid phase extraction followed with stable isotope labeling derivatization was developed for efficient sample pretreatment. The permanent positively charged moiety of d0/d3-MRSF significantly enhanced the ionization efficiency of neurotransmitters. The comparison results indicated that the synthesized MRSF derivatization method can bring better detection sensitivity than the commercial dansyl chloride method about tens to hundreds of times on the same instrumentation. Specific and regular product ions of m/z 413.3 and 416.3, m/z 429.4 and 432.4 were observed for d0-and d3-MRSF labeled neurotransmitters, respectively. The limits of detection were in the range of 2.0–40.0 pM. The accuracies ranged from 92.3% to 108.2% with the intra- and inter-day precisions in the range of 2.2–12.8%. Synchronous and dynamic determination of concentrations changes of brain neurotransmitters and blood gastrodin of PSD rats was achieved. The results indicated that gastrodin had analogous regulating effect of brain neurotransmitter, which like the clinical medicine fluoxetine of PSD. Taken together, the developed method was demonstrated to be promising for sensitive, accurate and simultaneous determination of multiple neurotransmitters in trace biofluids.Graphical abstractA new strategy of stable isotope labeling derivatization combined with magnetic dispersive solid phase extraction has been developed for the specific extraction and determination of multiple neurotransmitters in PSD rat brain microdialysates by UHPLC-MS/MS with high detection sensitivity, specificity and accuracy. The developed and validated method was successfully applied for the synchronous measurement of brain neurotransmitters and blood gastrodin pharmacokinetics of PSD rats in the combination with dual sites in vivo microdialysis sampling technique.Image 1
  • Sensors based on ruthenium-doped TiO2 nanoparticles loaded into
           multi-walled carbon nanotubes for the detection of flufenamic acid and
           mefenamic acid
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Nagaraj P. Shetti, Deepti S. Nayak, Shweta J. Malode, Raghava Reddy Kakarla, Shyam S. Shukla, Tejraj M. Aminabhavi Recent advances to utilize two or more nanoparticles for developing novel sensors with superior sensitivity have spurred advanced detection limits even at low concentrations. In this research, a blend of rutheniumdoped TiO2 (Ru-TiO2) nanoparticles and multiwalled carbon nanotubes (MWCNTs) loaded into carbon paste matrix to fabricate a novel Ru-TiO2/MWCNTs-CPE sensor was used for the detection and quantification of flufenamic acid (FFA) and mefenamic acid (MFA) drugs. The surface morphology of Ru-TiO2 was assessed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). Sensitivity and selectivity of the electrode was improved at the Ru-TiO2/MWCNTs modified CPE compared to nascent CPE due to the amazing surface distinctive characteristics of the modifier at pH 5.0. The effect of concentration of the modifier, pH, pre-concentration time, sweep rate and concentration on signal enhancement of FFA and MFA was studied. The square wave voltammetry (SWV) currents are linearly related in the concentration range of 0.01 μM–0.9 μM with the detection limit values of 0.68 nM for FFA and 0.45 nM for MFA, respectively. The developed electrode assembly was used for the quantification of both the drug analytes in human urine samples.Graphical abstractImage 1
  • Understanding the dipyrone oxidation allying electrochemical and
           computational approaches
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Rayane N. Gomes, João R. Bezerra-Neto, Camila P. Sousa, Samuel L.S. Medeiros, Helena Becker, Janete Eliza S. Soares, Pedro de Lima-Neto, Adriana N. Correia Electroanalytical methodology by boron-doped diamond electrode (BDDE) associated to the square-wave voltammetry (SWV) for the determination of hydrolyzed dipyrone (DIP) in commercial formulations, raw natural waters and in human urine was developed. Through cyclic voltammetry (CV), it was shown that the oxidation of the DIP on the BDDE was irreversible with diffusional control. Computational studies suggested that the oxidation mechanism of DIP occurred with participation of two electrons and one proton. The analytical curves were obtained for concentrations of DIP ranging from 1.0 × 10−6 to 6.5 × 10−5 mol L−1 (r = 0.9994). The values of detection limit (LOD) and quantification limit (LOQ) of DIP were calculated from SWV and found to be 2.6 × 10−7 mol L−1 and 8.8 × 10−7 mol L−1. The methodology was effectively applied to real samples with the values of calculated recoveries varying between 91.0% and 117.3% and validated by iodometric titration experiments whose values were between 93.3% and 106.9%. The proposed methodology with BDDE represents an alternative tool and it has advantageous, such as very easy handling, low cost, no need for modification, low detection limit. Furthermore, it can be used for the routine analysis of DIP in different real samples.Graphical abstractImage 1
  • Selective capillary electrophoresis separation of mono and divalent
           cations within a high-surface area-to-volume ratio multi-lumen capillary
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Nobutake Nakatani, Joan M. Cabot, Shing Chung Lam, Estrella Sanz Rodriguez, Brett Paull In this study, the separation of inorganic mono and divalent cations using multi-lumen silica capillaries (MLCs) of 126 channels, each with either 4 or 8 μm inner diameter, was investigated using capillary electrophoresis and on-capillary capacitively coupled contactless conductivity detection (CE-C4D). MLCs provided sufficiently high surface area-to-volume ratios to generate significant wall ion-exchange interactions for the divalent cations, which significantly affected resultant selectivity, whereas monovalent cations were predominantly separated by simple electrophoresis. The resultant hybrid selectivity was seen for both 4 and 8 μm channel multi-lumen capillaries, without any preconditioning or capillary wall modification. Remarkably, the electrophoretic mobilities for the divalent cations Mg2+ and Ca2+ were reduced 7.5 times compared to those determined using a single channel open tubular capillary of 50 μm i.d., providing much improved selectivity. Apparent electrophoretic mobilities of divalent cations increased as the concentration of BGE increased, while those of monovalent cations decreased parallel to electroosmotic mobility. These results show the electrostatic interaction between the divalent cations and the silica wall. At least, this specific separation of mono- and divalent cations were clearly observed with a mixture standards solution of less than 200 μmol L−1. Using a MLC with 126 × 8 μm i.d. channels and 49.1 cm in length, together with a 20 mmol L−1 MES/His BGE, containing 2 mmol L−1 18-crown-6, monovalent cations (NH4+, K+ Na+ and Li+) and divalent cations (Ca2+ and Mg2+) could be completely separated within 4 min. For monovalent cations, on-capillary detection using C4D provided calibration curve (0–200 μmol L−1) correlation coefficients in the range R2 = 0.995–0.999, and limits of detection of 2.2–6.6 μmol L−1. Relative standard deviations for migration times were less than 0.6%, and recoveries ranged from the 93.8%–105.4%. The new method was applied to the separation and quantitative determination of monovalent and divalent cations in drinking waters and soil extracts.Graphical abstractImage 1
  • Sparse NIR optimization method (SNIRO) to quantify analyte composition
           with visible (VIS)/near infrared (NIR) spectroscopy (350 nm-2500 nm)
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Yonatan Peleg, Shai Shefer, Leon Anavy, Alexandra Chudnovsky, Alvaro Israel, Alexander Golberg, Zohar Yakhini Visual-Near-Infra-Red (VIS/NIR) spectroscopy has led the revolution in high-throughput phenotyping methods used to determine chemical and structural elements of organic materials. In the current state of the art, spectrophotometers used for imaging techniques are either very expensive or too large to be used as a field-operable device. In this study we developed a Sparse NIR Optimization method (SNIRO) that selects a pre-determined number of wavelengths that enable quantification of analytes in a given sample using linear regression. We compared the computed complexity time and the accuracy of SNIRO to Marten's test, to forward selection test and to LASSO all applied to the determination of protein content in corn flour and meat and octane number in diesel using publicly available datasets. In addition, for the first time, we determined the glucose content in the green seaweed Ulva sp., an important feedstock for marine biorefinery. The SNIRO approach can be used as a first step in designing a spectrophotometer that can scan a small number of specific spectral regions, thus decreasing, potentially, production costs and scanner size and enabling the development of field-operable devices for content analysis of complex organic materials.Graphical abstractImage 1
  • Denoising influence on discrete frequency classification results for
           quantum cascade laser based infrared microscopy
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Paulina Koziol, Magda K. Raczkowska, Justyna Skibinska, Nicholas J. McCollum, Slawka Urbaniak-Wasik, Czeslawa Paluszkiewicz, Wojciech M. Kwiatek, Tomasz P. Wrobel Currently, there is great interest in bringing the application of IR spectroscopy into the clinic. This however will require a significant reduction in measurement time as Fourier Transform Infrared (FT-IR) imaging takes hours to days to scan a clinically relevant specimen. A potential remedy for this issue is the use of Quantum Cascade Laser Infrared (QCL IR) microscopy performed in Discrete Frequency (DF) mode for maximum speed gain. This gain could be furthermore improved by applying a proper denoising algorithm that takes into account the specific data structure. We have recently compared spectral and spatial denoising techniques in the context of Fourier Transform IR (FT-IR) imaging and showed that the optimal methods depend heavily on the exact data structure. In general multivariate denoising methods such as Principal Component Analysis (PCA) and Minimum Noise Fraction (MNF) are the most effective for a dataset containing multiple bands. Histologic classification of QCL IR images of pancreatic tissue using Random Forest was therefore performed to investigate which denoising schemes are the most optimal for such experimental data structure. This work is the first to show the effects of denoising on classification accuracy of QCL data and is likely to be transferable to other QCL microscopes and other modalities using DF imaging, e.g. AFM-IR or CARS/SRS imaging.Graphical abstractImage 1
  • Electrochemical aptamer-based sensors for food and water analysis:
           A review
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Fengqin Li, Zhigang Yu, Xianda Han, Rebecca Y. Lai Global food and water safety issues have prompted the development of highly sensitive, specific, and fast analytical techniques for food and water analysis. The electrochemical aptamer-based detection platform (E-aptasensor) is one of the more promising detection techniques because of its unique combination of advantages that renders these sensors ideal for detection of a wide range of target analytes. Recent research results have further demonstrated that this technique has potential for real world analysis of food and water contaminants. This review summaries the recently developed E-aptasensors for detection of analytes related to food and water safety, including bacteria, mycotoxins, algal toxins, viruses, drugs, pesticides, and metal ions. Ten different electroanalytical techniques and one opto-electroanalytical technique commonly employed with these sensors are also described. In addition to highlighting several novel sensor designs, this review also describes the strengths, limitations, and current challenges this technology faces, and future development trend.Graphical abstractImage 1
  • Outside Front Cover
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s):
  • Molecular structure regulation and enzyme cascade signal amplification
           strategy for upconversion ratiometric luminescent and colorimetric
           alkaline phosphatase detection
    • Abstract: Publication date: 21 March 2019Source: Analytica Chimica Acta, Volume 1051Author(s): Hongyu Chen, Zile Zhou, Qiujun Lu, Cuiyan Wu, Meiling Liu, Youyu Zhang, Shouzhuo Yao Herein, molecular structure regulation and enzyme cascade signals amplification (MRECAmp) strategy was proposed to construct a novel upconversion ratiometric fluorescence and colorimetric dual-readout assay platform for highly sensitive and selective detection of alkaline phosphatase (ALP) activity. The detection strategy is divided into three aspects. Firstly, Ag+ oxidates o-phenylenediamine (OPD) to 2,3-diaminophennazine (OPDox), which can significantly quench upconversion fluorescence at 487 nm based on inner filter effects (IFE) while the upconversion emission at 668 nm was essentially unchanged for Zn2+-doped NaYF4:Yb3+,Er3+,Tm3+ upconversion nanoparticles (UCNPs) probes under the near-infrared (NIR) irradiation. Secondly, ALP catalyzes the hydrolysis of the substrate l-ascorbic acid 2-phosphate (AAP) to ascorbic acid (AA) which can consume part of Ag+ to inhibit the generation of OPDox and the AA was oxidized to dehydroascorbic acid (DHAA). The specific performance of DHAA molecular structure regulation, due to the condensation reaction between dicarbonyl group of DHAA and diamine group of OPD, that is confirmed by ESI-MS and 1H NMR spectra analysis, can remarkably enhance the selectivity of ALP detection, which is conceptually different from the previously reported ALP fluorescent assays. Thirdly, the generated DHAA reacts with OPD to form 3-(dihydroxyethyl)furo [3,4-b]quinoxaline-1-one (DFQ) that further inhibits the generation of OPDox, which makes the enzyme-controlled cascade signal amplification (ECAmp) can be realized with a great fluorescence recovery (60.04%) at 487 nm. Therefore, the fluorescence response signal ((I487/I668)0/(I487/I668)) is amplified by ECAmp strategy, allowing the quantitative analysis of ALP with a detection limit of 0.03 mU/mL. The detection of ALP activity in human serum samples over the conventional methods demonstrates that the MRECAmp method provides a sensing platform for probing ALP activity and shows promising outlook in biomedical studies.Graphical abstractImage 1
  • Analytical nanometrological approach for screening and confirmation of
           titanium dioxide nano/micro-particles in sugary samples based on Raman
           spectroscopy – Capillary electrophoresis
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Virginia Moreno, Mohammed Zougagh, Ángel Ríos Analytical nanometrology is a present challenge in today's analytical science, particularly from a practical point of view and when it is addressed to routine/control laboratories. In this way, a screening-confirmation approach is described for the characterization and distinction between titanium dioxide nano/micro-particles in sugary food samples. The first step involves the confirmation of the presence of TiO2 in the sample (used as additive E171 in sugary samples), using a portable Raman spectrometer, in which the crystalline structure of TiO2 (anatase or rutile) in the positive samples can be also obtained in this step. Then, the second step was only applied to positive samples, and it involves the use of Capillary Electrophoresis (CE), which allows to distinguish between TiO2-nanoparticles (100 nm). Additionally, nanoparticles (TiO2 anatase (5 nm diameter) and TiO2 rutile (60 nm diameter) and rutile microparticles (0.1–0.2 μm diameter) can be electrophoretically separated. The general procedure is simple, fast, and low cost, providing a valuable analytical tool in the field of food safety and control, thus contributing to the development of the analytical nanometrology.Graphical abstractImage 1
  • Ultrasensitive “signal-on” electrochemical aptasensor for assay of
           acetamiprid residues based on copper-centered metal-organic frameworks
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Xueying Qiao, Fangquan Xia, Dong Tian, Peipei Chen, Jianhui Liu, Jinsong Gu, Changli Zhou In present work, a versatile “signal-on” electrochemical aptasensor with ultra-sensitivity and high selectivity for detecting acetamiprid residues has been successfully constructed. Electrochemistry behaviors of as-synthesized copper-centered metal-organic frameworks (CuMOF) on various electrodes were investigated in details. The results indicated that CuMOF exhibited well-behaved redox events. Thus, we used Au-CuMOF as signaling element to label probe DNA (pDNA). The gold nanoparticles-reduced graphene oxide (Au-rGO) has a high specific surface area and excellent conductivity, which was utilized to immobilize complementary strand (cDNA). In the presence of acetamiprid, Au-CuMOF-labeled pDNA would hybridize with the exposed cDNA, allowing CuMOF to approach the electrode and produce a sensitive signaling current. Such a “signal-on” method does not suffer from the drawbacks of “signal-off” methods. The linear range of this proposed electrochemical aptasensor was 0.1 pM–10.0 nM and the detection limit was as low as 2.9 fM. This platform exhibited wonderful selectivity, stability, and repeatability, and was successfully applied to detect acetamiprid residues in tea samples exhibiting enormous practical application potential.Graphical abstractImage 1
  • A novel helper qPCR system for platinum detection via Pt-DNA coordination
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Sheng Cai, Dan Yang, Xueke Tian, Jiawei Ye, Mingcheng Xu, Abdu Ahmed Abdullah AL-maskri, Cheulhee Jung, Su Zeng A novel real-time polymerase chain reaction (qPCR) platform for the simple and robust detection of platinum is described for the first time. Compared with conventional qPCR, a helper template, which is related to the active template for performing qPCR, was introduced in our helper qPCR system. Several guanine (G) bases were introduced in the helper template to obtain a platinum-responsive on/off switch based on G-Pt-G coordination. Because of the helper template, a slight change in platinum concentration would significantly change the signal in the qPCR. This novel helper qPCR technique easily detects platinum with high sensitivity (1 ng/mL) and selectivity over other metal ions. Therefore, it will be a promising technique for the detection of platinum in biomedical and environmental samples.Graphical abstractA novel real-time polymerase chain reaction (qPCR) platform for the simple and robust detection of platinum is described in this paper. Helper template, which is related to the active template for performing qPCR and enhance the efficiency of conventional qPCR, is introduced in our helper qPCR system. Due to its high sensitivity and selectivity, it would be a promising technique for the detection of platinum in biomedical and environmental samples.Image 1
  • Carbon dot-decorated porous organic cage as fluorescent sensor for rapid
           discrimination of nitrophenol isomers and chiral alcohols
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Zhenyu Lu, Xiaotian Lu, Yanhui Zhong, Yufei Hu, Gongke Li, Runkun Zhang Isomers discrimination plays a vital role in modern chemistry, and development of efficient and rapid method to achieve this aim has attracted a great deal of interest. In this work, a novel carbon dot-decorated chiral porous organic cage hybrid nanocomposite (CD@RCC3) was prepared and used to fabricate fluorescent sensor. The resultant CD@RCC3 was characterized by using a range of techniques, finding that CD@RCC3 possesses strong and stable fluorescent property in common organic solvents, especially it exhibits chiral property. The potential application of CD@RCC3 in fluorescence sensing was demonstrated by isomers discrimination. The designed sensor was successfully used to rapid discriminate nitrophenol isomers. Meanwhile, it exhibited differentiation ability towards phenylalaninol and phenylethanol enantiomers. Our work enriches the type of synthetic materials for fluorescence sensing, and provides a simple method for distinguishing structural isomers and chiral isomers.Graphical abstractImage 1
  • Dihydropteroate synthase based sensor for screening multi-sulfonamides
           residue and its comparison with broad-specific antibody based immunoassay
           by molecular modeling analysis
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Xiao Liang, Chenglong Li, Jianyu Zhu, Xiaoli Song, Wanpeng Yu, Jing Zhang, Suxia Zhang, Jianzhong Shen, Zhanhui Wang A biosensor that could simultaneously detect multi-analyte as many as in a single test is more favored when facing lots of samples for screening purpose. In such a biosensor, the recognition element with broad specificity and highly affinity is a key reagent for detection spectrum. Here we report a dihydropteroate synthase (DHPS) based biosensor for detecting 29 sulfonamides (SAs) in milk. The biosensor was established in a competitive format where HRP-labeled tracer and free SAs competitively binding to the limited amount of DHPS-DHPPP (6-hydroxymethyl-7,8-dihydropterin diphosphate) binary complex. Compared to other biosensors based on antibodies with the same objective, the current sensor employing DHPS provided not only highly sensitivity but also preponderant uniform affinities for all individual sulfonamide, which has never been achieved before in any immunosensor. However, the difference of recognition mechanism between DHPS and antibody remains unknown. To address this question, we deconstructed the variable region of two monoclonal antibodies produced by our group and then compared the intermolecular forces and key contacting amino acid residues of both DHPS and antibodies to several typical SAs with help of molecular modeling analysis. Results showed the orientation of the ligands in the binding site played a significant role during the recognition with proteins. The optimized assay provided a limit of detection (LOD) of 1.15–14.91 ng mL−1 and dynamic range was ranging from 1.54 to 126.85 ng mL−1 for 29 SAs. The developed biosensor finally was validated for five SAs in spiked milk with recovery values ranging from 72.7 to 129.3% and coefficients of variation less than 16.0%. The study showed that the biosensor based on DHPS make it a suitable screening method for the simultaneous determination of total SAs residues in food matrices.Graphical abstractImage 1
  • Single-step, high-specificity detection of single nucleotide mutation by
           primer-activatable loop-mediated isothermal amplification (PA-LAMP)
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Wen-Fang Du, Jian-Hui Ge, Jun-Jie Li, Li-Juan Tang, Ru-Qin Yu, Jian-Hui Jiang Loop-mediated isothermal amplification (LAMP) is a useful platform for nucleic acids detection in point-of-care (POC) situations, and development of single-step, close-tube LAMP reactions for specific detection of single nucleotide mutations (SNMs) remains a challenge. We develop a novel primer-activatable LAMP (PA-LAMP) strategy that enables highly specific and sensitive SNM detection using single-step, close-tube reactions. This strategy designs a terminal-blocked inner primer with a ribonucleotide insertion, which is cleaved and activated specifically to perfectly matched targets by ribonuclease (RNase) H2, to realize efficient amplification of mutant genes. It has shown dynamic responses of mutant target in a linear range from 220 aM to 22 pM with a lowest detectable concentration of 22 aM. It also demonstrates very high specificity in identifying the mutant in a large excess of the wild-type with a discrimination ratio as high as ∼10,000. It has been successfully applied to mutation detection of genomic DNA in tumor cells. The PA-LAMP strategy provides a useful, portable and affordable POC platform for highly sensitive and specific detection of genetic mutations in clinical applications.Graphical abstractImage 1
  • Dual redox labeling of DNA as a tool for electrochemical detection of p53
           protein-DNA interactions
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Monika Hermanová, Petr Orság, Jana Balintová, Michal Hocek, Miroslav Fojta We present a novel dual redox labeling approach enabling a facile relative evaluation of protein-DNA interactions based on immunoprecipitation at magnetic beads (MBIP) with subsequent electrochemical detection. DNA probes labeled with two different electroactive markers, benzofurazane and nitrobenzene, which yield reduction peaks at distinct potentials, were synthesized using primer extension (PEX) reaction. We show that using the labeled DNA probes, specific and non-specific binding of the p53 protein can be distinguished in a simple competition binding experiment, as a strong preference of the p53 protein was observed towards DNA probes bearing a specific p53 binding site (p53CON), which is in agreement with known binding properties of the p53 protein. The p53 binding to the individual DNA probes can be modulated by specific monoclonal antibodies used for the immunoprecipitation. This approach can potentially be applied, after selection of appropriate DNA probes and monoclonal antibodies, for investigations of DNA-binding properties of other proteins and thus represents a versatile tool for studies of any DNA-binding proteins.Graphical abstractImage 1
  • Integrated analyses utilizing metabolomics and transcriptomics reveal
           perturbation of the polyamine pathway in oral cavity squamous cell
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Chia-Wei Hsu, Yi-Ting Chen, Ya-Ju Hsieh, Kai-Ping Chang, Pei-Chun Hsueh, Ting-Wen Chen, Jau-Song Yu, Yu-Sun Chang, Liang Li, Chih-Ching Wu Oral cavity squamous cell carcinoma (OSCC), the most common malignancy of the oral cavity, is associated with poor prognosis and high mortality worldwide. Moreover, knowledge of the metabolic alterations that occur in OSCC is still limited. In the present study, we used a quantitative metabolomic approach with chemical isotope labeling (CIL) to analyze alterations in the metabolite levels in paired cancerous (T) and adjacent noncancerous (AN) tissues from 31 OSCC patients. Using volcano plot and orthogonal projections to latent structure-discriminant analysis (OPLS-DA), we uncovered 99 dysregulated metabolites in OSCC and verified the identities of seven metabolites via comparison with authenticated standards. From these seven metabolites, we constructed a 3-marker panel, consisting of putrescine, glycyl-leucine, and phenylalanine, using a support vector machine (SVM) model that can discriminate T from AN with high sensitivity and specificity based on receiver operator characteristic (ROC) analysis. Furthermore, by integrating the metabolomics profiles with transcriptomics data obtained from the same sample set, we revealed the dysregulation of the polyamine pathway in OSCC. Our findings provide insights into the metabolic perturbations present in OSCC and have uncovered potential metabolic biomarkers and therapeutic targets for use in the treatment of OSCC.Graphical abstractImage 1
  • Analytical properties of electrospray ionization mass spectrometry with
           solid substrates and nonpolar solvents
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Zhengxu Huang, Ya-Nan Yao, Wen Li, Bin Hu Electrospray ionization mass spectrometry (ESI-MS) is one of the most powerful ionization techniques for characterization of analytes in various areas. Polar solvents such as methanol, water and acetonitrile are commonly used for ESI-MS analysis, while nonpolar solvents such as hexane were usually considered as non-ESI-friendly solvents. Following our recent work on observation of ESI process from solid substrates using nonpolar solvents (Anal Chim Acta, 2018, 1004, 51–57), the analytical properties of ESI-MS with solid substrates and nonpolar solvents were further systematically investigated in this study. Compared to the uses of polar solvents, our results revealed that nonpolar solvents could serve as extractants for enhanced detection of low-polar analytes from complex samples, and could serve as refrigerants for rapid freezing of samples such as peptides, proteins and protein-ligand complexes. Furthermore, nonpolar solvents could be used for formation of ammonia-transition-metal acetylacetonates complexes under ambient conditions.Graphical abstractImage 1
  • Development of chemical isotope labeling LC-MS for tissue metabolomics and
           its application for brain and liver metabolome profiling in Alzheimer's
           disease mouse model
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Xiaohang Wang, Wei Han, Jing Yang, David Westaway, Liang Li Tissue metabolomics can play an important role in biological studies and biomarker discovery. However, high-coverage metabolome analysis of tissue samples remains a challenge. In this work, we report an analytical method for in-depth tissue metabolome profiling with highly accurate metabolite quantification. This method is based on tissue homogenization with an extraction solvent mixture of methanol, dichloromethane and water, high-performance differential chemical isotope labeling (CIL) of metabolite extracts, followed by high-resolution liquid chromatography mass spectrometry (LC-MS) detection of labeled metabolites. The method development was initially carried out using chicken liver tissue. To demonstrate the analytical performance and potential applications of this approach in real world tissue metabolomics, we examined changes in the amine/phenol submetabolome of liver and brain tissues from an Alzheimer's disease (AD) mouse model. A total of 2319 and 1769 peak pairs or amine-/phenol-containing metabolites were commonly detected in 80% of the liver samples (n = 22) and 80% of the brain samples (n = 22), respectively. In liver samples, 89 metabolites were positively identified using labeled standard library and 1063 peak pairs were putatively matched to metabolome databases, while 78 were positively identified and 753 were putatively matched in brain samples. Using multivariate and univariate analyses to study these metabolites, we observed significant metabolome differences between AD transgenic mice and wild-type mice in both liver and brain tissues, with several metabolite biomarker candidates having good discriminative power. We envisage that the CIL LC-MS method reported herein can be used in various application areas requiring in-depth analysis of tissue metabolomes.Graphical abstractImage 1
  • Development of an on–site detection approach for rapid and highly
           sensitive determination of persistent organic pollutants in real aquatic
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Qingkun Hu, Shuqin Liu, Yan Liu, Xu'an Fang, Jianqiao Xu, Xiao Chen, Fang Zhu, Gangfeng Ouyang Analysis of organic pollutants is usually accomplished in centralized laboratories. However, the time-delayed and time-consuming process is insufficient and risky for precisely detection due to the contamination of vials, the losses of analytes during transportation and storage. Herein, a rapid and highly sensitive on-site detection approach was developed without using any vials by coupling an on-site pre-equilibrium solid phase microextraction (SPME) sampling method with a portable gas chromatography mass spectrometer (portable GC-MS), for the determination of three families of persistent organic pollutants (polychlorinated biphenyls, organochlorine pesticides and polycyclic aromatic hydrocarbons). Based on sampling-rate (SR) calibration method, the concentrations of target analytes in aquatic systems could be easily determined. Limits of detection (LODs) in the low parts-per-tillion levels (≤5.25 ng·L−1) were obtained for most of the investigated analytes with a total analysis time only ∼30 min. The proposed on-site detection approach was then successfully applied in the determination of persistent organic pollutants in real aquatic environment. A comparable result obtained by liquid extraction (LE) equipped with laboratorial GC-MS demonstrated the accuracy of the on-site detection method. In general, this study demonstrated a rapid and highly sensitive on-site approach, avoiding any risks of contamination during sampling and analysis, for determination of POPs as well as the potential applications for other organic pollutants in aquatic phase.Graphical abstractImage 1
  • A streamlined strategy for rapid and selective analysis of serum N-glycome
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Ye Peng, Jing Lv, Lijun Yang, Danqing Wang, Ying Zhang, Haojie Lu N-glycome profile of serum has been considered as potential source of biomarker discovery for decades. However, the time-consuming sample preparation and difficulties in N-glycan enrichment limit N-glycome exploration and further applications. Here, a strategy for rapid N-glycome profiling of complex biological samples has been developed. Easy-to-prepare and cost-friendly sterilized cotton is utilized as a matrix for sample absorption, quick enzymatic deglycosylation, and highly selective N-glycan enrichment. Using this multifunctional matrix, a corresponding centrifuge-assisted sample preparation approach and its protocol were developed. Sample preparation could be completed within 2.5 h, while traditional methods usually cost more than 24 h. Additionally, selectivity towards glycan was increased 100 folds than commercially available purification microtips, making the detection more sensitive. Finally, this strategy was successfully applied to analyze the serum N-glycome of colorectal cancer (CRC) patients and healthy individuals, the glycan ratio (Hex5HexNAc4Sia2/Hex5HexNAc4Sia1) was found to significantly increase among CRC patients.Graphical abstractImage 1
  • Low-temperature fusion using NH4HSO4 and NH4HF2 for rapid determination of
           Pu in soil and sediment samples
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Hai Wang, Youyi Ni, Jian Zheng, Zhaoya Huang, Detao Xiao, Tatsuo Aono Two fusion methods were established for rapid determination of Pu in soil and sediment samples. The methods consisted of NH4HSO4 or NH4HF2 fusion procedures incorporated with procedures for CaF2/LaF3 co-precipitation, extraction chromatography and SF-ICP-MS measurement. The fusion procedures were done on a portable hot plate instead of in a cumbersome muffle furnace and took only 15 min heating-up time from room temperature to 250 °C and 15 min fusion time at 250 °C. Chemical recoveries of Pu after completing the NH4HSO4 and NH4HF2 fusion methods for 0.5–1 g sample were approximately 70% and more than 90%, respectively, and decreased with the increase of sample weight from 0.5 g to 5 g. Sediment samples were pre-ignited at different temperatures ranging from 450 °C to 1000 °C to form refractory fractions of Pu, with which the dissolution rates of Pu by the NH4HSO4 and NH4HF2 fusion were investigated. With the increase of pre-ignition temperature of the sediment samples, the dissolution rates of Pu from the samples prepared by NH4HSO4 fusion declined dramatically from near 100% for 450 °C to 8% for 1000 °C. In contrast, the NH4HF2 fusion was capable of completely releasing Pu from samples that were pre-ignited at temperatures over 450 °C to 1000 °C, which was comparable to releases obtained by the hazardous and time-consuming HNO3-HF digestion, and was superior to the conventional HNO3 digestion. Additionally, because HF is not used in any procedure of the NH4HF2 fusion, a safer and greener alternative to NH4HSO4 fusion and HNO3-HF digestion is realized for rapid Pu determination in environmental samples for nuclear emergency response and application in environmental studies.Graphical abstractImage 1
  • Application of the voltammetric electronic tongue based on nanocomposite
           modified electrodes for identifying rice wines of different geographical
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Jun Wang, Luyi Zhu, Weilin Zhang, Zhenbo Wei In the study, the voltammetric electronic tongue based on three nanocomposites modified electrodes was applied for the identification of rice wines of different geographical origins. The nanocomposites were prepared by gold and copper nanoparticles in the presence of conducting polymers (polymer sulfanilic acid, polymer glutamic acid) and carboxylic multi - walled carbon nanotubes. The modified electrodes showed high sensitivity to guanosine - 5' - monophosphate disodium salt, tyrosine and gallic acid which have good correlation with the geographical origins of rice wines. Scanning electron microscopy was performed to display the surface morphologies of the nanocomposites, and cyclic voltammetry was applied to study the electrochemical behaviors of the taste substances on the electrode surfaces. Four types of electrochemical parameters (pH, scan rates, accumulation potentials and time) were optimized for getting a low limit of the detection of each taste substance. The geographical information of rice wines was obtained by the modified electrodes based on two types of multi - frequency large amplitude pulse voltammetry, and “area method” was applied for extracting the feature data from the original information obtained. Based on the area feature data, principal component analysis, locality preserving projection (LPP), and linear discriminant analysis were applied for the classification of the rice wines of different geographical origins, and LPP presented the best results; extreme learning machine (ELM) and alibrary for support vector machines were applied for predicting the geographical origins of rice wines, and ELM performed better.Graphical abstractImage 1
  • Retention-pH profiles of acids and bases in hydrophilic interaction liquid
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Tamara Alvarez-Segura, Xavier Subirats, Martí Rosés The high proportion of acetonitrile used in many HILIC mobile phases significantly changes the acid-base properties of pH buffers and analytes foreseen from available data in water. In this paper, the recommended stability pH range for chromatographic columns is examined with various acetonitrile/water mixtures, resulting in a significant broadening in the operational pH window with the content of organic solvent. Additionally, the challenge of buffer selection in HILIC is also addressed. Commonly used ammonium acetate shrinks its pH buffering range in acetonitrile-rich mobile phases due to variations in the dissociation constants of the buffer constituents (acetic acid and ammonium). Thus, other organic acids such as formic acid, TFA, and succinimide have been studied as buffers in order to fully cover the pH range of use of the column. Also the retention-pH profiles of several acids and bases have been studied in 80% and 90% acetonitrile using the proposed buffers and their behavior compared to that obtained with buffers prepared from oxalic acid, pyrrolidine, and triethylamine. The latter two show additional interactions in 80% acetonitrile that distort the expected retention-pH profiles of acid analytes, but not the ones of bases. In 90% acetonitrile the profiles are affected by significant additional solute-buffer interactions that might be caused by ion pairing, homo- and heteroassociation in this low ion solvating medium.Graphical abstractImage 1
  • Harvesting energy from cellulose through Geobacter sulfurreducens in
           Unique ternary culture
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Yujing Jiang, Rongbin Song, Lianbin Cao, Zhaoying Su, Yamei Ma, Ying Liu In this study, both electricity generation capability and biodegradation process of carboxymethyl cellulose (CMC) were investigated using a defined ternary culture of Paenibacillus sp., Klebsiella sp. and Geobacter sulfurreducens as biocatalysts in MFCs. The maximum current density achieved by the ternary culture from CMC was 621 ± 23 μA cm−2 in half-cell experiments and the maximum power density reached to 1146 ± 28 mW m−2 in two-chamber MFCs. Meanwhile, the ternary culture also possessed three times higher CMC degradation capability compared to the pure strain J1. Besides, the key metabolite products, including cellobiose, glucose, acetate, were quantified by high performance liquid chromatography (HPLC) to illustrate the biodegradation process of CMC. The high electricity generation performance mainly resulted from the “division-of-labor” based cooperation and the enhanced extracellular electron transfer caused by the electron shuttle secreted by Klebsiella sp. This study highlighted the synergistic effect of specific community on electricity generation using CMC as carbon source, and laid the foundation for further optimization of more efficient and stable microbial consortia for bioenergy applications.Graphical abstractImage 1
  • Efficient quantitative hyperspectral image unmixing method for large-scale
           Raman micro-spectroscopy data analysis
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): E.G. Lobanova, S.V. Lobanov Vibrational micro-spectroscopy is a powerful optical tool, providing a non-invasive label-free chemically specific imaging for many chemical and biomedical applications. However, hyperspectral image produced by Raman micro-spectroscopy typically consists of thousands discrete pixel points, each having individual Raman spectrum at thousand wavenumbers, and therefore requires appropriate image unmixing computational methods to retrieve non-negative spatial concentration and corresponding non-negative spectra of the image biochemical constituents. Here, we present a new efficient Quantitative Hyperspectral Image Unmixing (Q-HIU) method for large-scale Raman micro-spectroscopy data analysis. This method enables to simultaneously analyse multi-set Raman hyperspectral images in three steps: (i) Singular Value Decomposition with innovative Automatic Divisive Correlation which autonomously filters spatially and spectrally uncorrelated noise from data; (ii) a robust subtraction of fluorescent background from the data using a newly developed algorithm called Bottom Gaussian Fitting; (iii) an efficient Quantitative Unsupervised/Partially Supervised Non-negative Matrix Factorization method, which rigorously retrieves non-negative spatial concentration maps and spectral profiles of the samples' biochemical constituents with no a priori information or when one or several samples’ constituents are known. As compared with state-of-the-art methods, our approach allows to achieve significantly more accurate results and efficient quantification with several orders of magnitude shorter computational time as verified on both artificial and real experimental data. We apply Q-HIU to the analysis of large-scale Raman hyperspectral images of human atherosclerotic aortic tissues and our results show a proof-of-principle for the proposed method to retrieve and quantify the biochemical composition of the tissues, consisting of both high and low concentrated compounds. Along with the established hallmarks of atherosclerosis including cholesterol/cholesterol ester, triglyceride and calcium hydroxyapatite crystals, our Q-HIU allowed to identify the significant accumulations of oxidatively modified lipids co-localizing with the atherosclerotic plaque lesions in the aortic tissues, possibly reflecting the persistent presence of inflammation and oxidative damage in these regions, which are in turn able to promote the disease pathology. For minor chemical components in the diseased tissues, our Q-HIU was able to detect the signatures of calcium hydroxyapatite and β-carotene with relative mean Raman concentrations as low as 0.09% and 0.04% from the original Raman intensity matrix with noise and fluorescent background contributions of 3% and 94%, respectively.Graphical abstractImage 1
  • A two-level strategy for standardization of near infrared spectra by
           multi-level simultaneous component analysis
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Jin Zhang, Cheng Guo, Xiaoyu Cui, Wensheng Cai, Xueguang Shao Standardization of near infrared (NIR) spectra is indispensable in practical applications because the spectra measured on different instruments are commonly used and the difference between the instruments must be corrected. A two-level standardization method is proposed in this study based on multi-level simultaneous component analysis (MSCA) algorithm for correcting the spectral difference between instruments. A two-level MSCA model is used to model the difference between instruments (the first level) and samples (the second level). With the two models, the spectral difference due to instruments and measurement operation can be corrected, respectively. Three NIR spectral datasets of pharmaceutical tablet, corn and plant leaf are used to evaluate the efficiency of the proposed method. The results show that the score of the first level model describes the overall spectral difference between instruments, and the score of the second level model depictures the spectral difference of the same sample between the measurements. The latter difference may include the spectral variations caused by instrument, operation and the measurement conditions. Therefore, both the spectral difference due to the instrument and measurement can be corrected by adjusting the coefficients in the scores of the two level models, respectively. The proposed method provides a good way for standardizing the spectra measured on different instruments when the measurement is not reproducible.Graphical abstractImage 1
  • Structure/reaction directed analysis for LC-MS based untargeted analysis
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Miao Yu, Mariola Olkowicz, Janusz Pawliszyn In LC-MS based untargeted analysis, data is collected at the peak or ion level, although the investigated biochemistry processes occur at the compound or reaction level. To this end, the presence of redundancy peaks such as co-eluted peaks, multi-chargers, adducts, neutral loss, isotopologues, and fragments ions often muddle subsequent statistical data analysis. In order to fill this gap, between peaks and compounds/reactions, independent components must first be found at the peak level, then evaluated at the compound or reaction levels. Based on paired mass distances (PMD), the algorithm GlobalStd, based on retention time hierarchical cluster analysis and global analysis of PMDs within clusters, is here proposed to extract independent peaks from raw LC-MS data. Following its application, a structure/reaction directed analysis can then be used to evaluate compounds at the structure or biochemistry reaction level, based on similar PMDs among different retention times clusters. As a proof-of-concept, the developed statistical method was applied to data obtained for in vivo SPME sampling on fish. In total, 277 independent peaks were demonstrated to stand for most of the variances found for the total 1459 ions detected via LC-MS. Following, both known homologous series or biological reactions along with unknown bio-processes, which may involve oxidation/reduction reactions or homologous series, were analyzed via a structure/reaction directed analysis. The findings of this analysis yielded interesting information regarding the data, for instance denoting the possible occurrence of a biosynthesis process involving l-Carnitine and its precursor 4-Trimethylammoniobutanoic acid. Such PMD relationships could also aid in the screening of annotation results. To this end, semi-quantitative analysis based on structure/reaction directed analysis is also here proposed for further investigation of unknown patterns or for removal of contaminants in metabolomics studies. The developed data-driven algorithm has been included in a PMD package with a GUI interactive document, and is freely available online ( abstractImage 1
  • Nicking enzyme-assisted amplification (NEAA) technology and its
           applications: A review
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Cheng Qian, Rui Wang, Hui Wu, Feng Ji, Jian Wu Nucleic acid isothermal amplification detection technologies have undergone rapid development in the field of molecular diagnosis due to their freedom from the limitations of complex temperature control equipment. In recent years, with the use of newly discovered nicking endonucleases, a novel isothermal amplification technique, —nicking enzyme-assisted amplification (NEAA), has been developed. NEAA reactions offer high levels of amplification efficiency and can exponentially amplify a target nucleic acid over a very short period of time. NEAA has been widely used in many fields, including those of molecular diagnosis, disease detection, biochemical identification, and many more. NEAA reactions also present some drawbacks, (e.g., severe non-specific amplification and strong background signals.) The principle, advantages and disadvantages of NEAA technologies are discussed. Applications and comparisons of NEAA to similar methods are described in this review. We hope that this review will serve as inspiration for further NEAA research.Graphical abstractImage 1
  • Outside Front Cover
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s):
  • Simple and rapid detection of microplastics in seawater using
           hyperspectral imaging technology
    • Abstract: Publication date: 7 March 2019Source: Analytica Chimica Acta, Volume 1050Author(s): Jiajia Shan, Junbo Zhao, Yituo Zhang, Lifen Liu, Fengchang Wu, Xue Wang Microplastics (MPs) pollution in marine systems is attracting worldwide attentions, which highlights a pressing need for efficient detection methods. Traditional protocols generally identify the suspected particles individually, which are time-consuming. Hyperspectral imaging technique has emerged as a simple and rapid method to characterize MPs in seawater. However, hyperspectral image consists of amount of redundant and high correlated spectral information, resulting in the Hughes phenomenon for classification. This work aimed to identify MPs from the hyperspectral image using support vector machine (SVM) algorithm, which presents a good performance for analyzing nonlinear and high-dimensional data and is insensitive to the Hughes effect. In this work, SVM was performed to quantify and identify MPs in both of seawater and seawater filtrates. The factors which may affect the accuracy of SVM model were investigated, including organic particles, polymer types and particle sizes. SVM model yielded a satisfactory accuracy for all the tested pure polymers and it presented a highly robust for detecting MPs in a wide range of types and particle sizes. Finally, common household polymers were chosen to validate the developed model. The results illustrate that hyperspectral imaging technology combination with SVM method exhibits a high robustness and recovery rate for MPs detection.Graphical abstractImage 1
  • Fast gas chromatography-atmospheric pressure (photo)ionization mass
           spectrometry of polybrominated diphenylether flame retardants
    • Abstract: Publication date: Available online 18 January 2019Source: Analytica Chimica ActaAuthor(s): Robert A. Di Lorenzo, Vladislav V. Lobodin, Jack Cochran, Terry Kolic, Sladjana Besevic, John G. Sled, Eric J. Reiner, Karl J. Jobst Gas chromatography (GC) and mass spectrometry (MS) are powerful, complementary techniques for the analysis of environmental toxicants. Currently, most GC-MS instruments employ electron ionization under vacuum, but the concept of coupling GC to atmospheric pressure ionization (API) is attracting revitalized interest. API conditions are inherently compatible with a wide range of ionization techniques as well high carrier gas flows that enable fast GC separations. This study reports on the application of atmospheric pressure chemical ionization (APCI) and a custom-built photoionization (APPI) source for the GC-MS analysis of polybrominated diphenyl ethers (PBDEs), a ubiquitous class of flame retardants. Photoionization of PBDEs resulted in the abundant formation of molecular ions M•+ with very little fragmentation. Some photo-oxidation was observed, which differentiated critical BDE isomers. Formation of protonated molecules [M+H]+ did not occur in GC-APPI because the ionization energy of H2O (clusters) exceeds the energy of the ionizing photons. Avoiding mixed-mode ionization is a major advantage of APPI over APCI, which requires careful control of the source conditions. A fast GC-API-MS method was developed using helium and nitrogen carrier gases that provides good separation of critical isomers (BDE-49/71) and elution of BDE 209 in less than 7 minutes (with He) and 15 minutes (with N2). It will be shown that the GC-APPI and GC-APCI methods match the sensitivity and improve upon the selectivity and throughput of established methods for the analysis of PBDEs using standard reference materials (NIST SRM 1944 and SRM 2585) and selected environmental samples.Graphical abstractImage 1
  • Modulation of the electroosmotic mobility using polyelectrolyte multilayer
           coatings for protein analysis by capillary electrophoresis
    • Abstract: Publication date: Available online 18 January 2019Source: Analytica Chimica ActaAuthor(s): Laurent Leclercq, Marine Morvan, Jens Koch, Christian Neusüß, Hervé Cottet Successive multiple ionic-polymer layers (SMIL) coatings have been often used in capillary electrophoresis due to their simplicity to implement and regenerate. However, the performances of the separation are strongly dependent on the nature of the polyelectrolyte partners used to build the SMIL coating. In this work, we investigate new couples of polyelectrolytes that were tested before: namely, polybrene (PB), quaternized diethylaminoethyl dextran (DEAEDq) and ε-poly(lysine) (ε-PLL), as polycations, in combination with poly(acrylic acid), dextran sulfate, poly(styrenesulfonate), poly(methacrylic acid) and poly(L-lysine citramide), as polyanions. Systematic study of intra- and inter-capillaries repeatabilities/reproducibilities was performed based on the determination of migration time, separation efficiency and electroosmotic mobility. Interestingly, the electroosmotic flow was found to vary with the nature of the polycation on a broad range of electroosmotic mobility decreasing in magnitude in the order of PB>ε-PLL>DEAEDq, whatever the polyanion associated. Application of the coatings to the separation of proteins is illustrated in a 0.5 M acetic acid BGE, including CE-MS separation of ribonuclease B-glycoforms of the same mass (positional or structural isomers).Graphical abstractImage 1
  • Detection of Hydrogen Sulfide in Water Samples with
           2-(4-Hydroxyphenyl)-4,5-di(2-pyridyl)imidazole-Copper(II) Complex using
           Environmentally Green Microplate Fluorescence Assay Method
    • Abstract: Publication date: Available online 16 January 2019Source: Analytica Chimica ActaAuthor(s): Mahmoud H. El-Maghrabey, Riho Watanabe, Naoya Kishikawa, Naotaka Kuroda Hydrogen sulfide (H2S) is a colorless toxic gas which can be found as HS− in rivers and waste waters especially in the occupational susceptible environment. Herein we synthesized a lophine analogue, 2-(4-hydroxyphenyl)-4,5-di(2-pyridyl)imidazole (HPI), which fluoresce at 410 nm after excitation at 280 nm. HPI has an imidazole ring and a pyridine ring which are capable of forming coordinate bonds with copper (Cu(II)) that cause quenching of HPI fluorescence. We found that HS− can selectively liberate HPI from the complex via formation of CuS, thus HPI regains its fluorescence properties. Interestingly, the probe was proved to be regenerable. This reaction was used for the development of a fluorescence microplate assay for the determination of HS− in environmental samples. The method was applied to river water samples and was able to detect HS− in concentrations down to 5 ppb with acceptable accuracy (90.3-103.0%) and good precision (%RSD ≤ 4.1). The method showed many advantages over the previously reported ones including instantaneous reaction, simple probe synthesis, high-throughput, high selectivity toward hydrogen sulfide over other ions and sulfur or thiol containing compounds and at last, it complies with the green chemistry rules through using a regenerable probe, aqueous solvents, and miniaturized measurement system.Graphical abstractImage 1
  • Smartphone-based apparatus for measuring upconversion luminescence
    • Abstract: Publication date: Available online 20 December 2018Source: Analytica Chimica ActaAuthor(s): Zece Zhu Luminescence lifetime detection plays an important role in time-resolved detection and research. However, the traditional instruments always require expensive detectors such as time-correlated single photon counter or streak camera. Herein, a low-cost and miniaturized apparatus for measuring upconversion luminescence lifetimes was developed by using a smartphone equipped with a 980 nm CW laser and a motor. When the motor was driving the sample circling at a high linear velocity, the excited sample would emit a luminescence arc, which could be photographed by the phone camera. The rotating rate could be measured by a tuner APP and then used for transferring arc length to delay times. By analyzing the grayscale distribution of the luminescence arc, the luminescence decay curve was obtained, which was then used for exponential fit and calculating lifetimes. The images captured by different smartphones revealed similar lifetime values, suggesting a wide universality of this method. The whole system was not only remarkably cheaper but also more miniaturized than traditional instruments for measuring luminescence lifetimes, indicating the promising applications in point of care testing for time-resolved luminescence detection for bioanalysis and disease diagnosis.Graphical abstractImage 1
  • Quantitative analysis of asbestos in drinking water and its migration in
           mice using fourier-transform infrared spectroscopy and inductively coupled
           plasma optical emission spectrometry
    • Abstract: Publication date: Available online 19 December 2018Source: Analytica Chimica ActaAuthor(s): Bei Zheng, Lijie Zang, Wentao Li, Hongyan Li, Haitao Wang, Ming Zhang, Xiaohong Song The presence of asbestos in the environment has caused concern because exposure to asbestos can cause diseases such as stomach and pancreatic cancer. However, suitable up-to-date methods for quantitatively analyzing asbestos and assessing the toxicity of asbestos have not been developed. In this study, asbestos in drinking water was characterized using a stepwise multiple differential infra-red spectra method and a partial least squares method. The in vivo migration of ingested asbestos in mice was then investigated using the technique. The quantification limit of six kinds of asbestos by using inductively coupled plasma optical emission spectrometry and Fourier-transform infrared spectroscopy in water are respectively from 0.0468 to 0.0705 mg/L, from 0.0039 to 0.0064 mg/L. The relative standard deviations were respectively less than 2.85% and 3.81%. The recoveries of the test asbestos were respectively more than 95.10% and 95.38%. Asbestos was found mainly to accumulate in the livers of mice. The Fourier-transform infra-red spectroscopy inductively coupled plasma optical emission spectrometry method can be used to detect and precisely quantify asbestos in water samples and in animal tissues.Graphical abstractImage 1
  • Capillary electrophoresis with preparative isoelectric focusing
           preconcentration for sensitive determination of amphotericin B in human
           blood serum
    • Abstract: Publication date: Available online 18 December 2018Source: Analytica Chimica ActaAuthor(s): Jiří Šalplachta, Marie Horká, Karel Šlais Amphotericin B (AmB) is still, despite its severe nephrotoxicity, the first-line agent in the management of serious systemic fungal infections. A sensitive and reliable method is therefore required to control AmB concentration in body fluids of a patient. This study demonstrates the potential of the off-line combination of preparative isoelectric focusing (IEF) with capillary isoelectric focusing (CIEF) or capillary zone electrophoresis (CZE) in the determination of AmB in human blood serum. The required value of the isoelectric point of AmB was determined to be 6.1 using the CIEF technique. Preparative IEF served as a pre-separation and concentration technique. The pH gradient was traced by colored low molecular pI markers. The collected fraction with AmB was easily processed and then analyzed by CIEF and CZE. Tens of picograms of AmB in human blood serum sample can be determined by a combination of preparative IEF with CZE. The method was linear in the AmB concentration range of 0.3–600 ng mL−1. The recovery ranged from 93% to 98%.Graphical abstractImage 1
  • A dual-channel probe with green and near-infrared fluorescence changes for
           in vitro and in vivo detection of peroxynitrite
    • Abstract: Publication date: Available online 15 December 2018Source: Analytica Chimica ActaAuthor(s): Shumin Feng, Dandan Liu, Guoqiang Feng In this study, a coumarin-semirhodamine hybrid based dual-channel fluorescent probe was developed for detection of peroxynitrite. This probe works well in nearly pure aqueous solution and displays a rapid, highly sensitive and selective response for peroxynitrite at two different emission wavelengths (700 and 515 nm, respectively), along with distinct color and green to near-infrared fluorescence changes. The fluorescent intensity ratio at 700 and 515 nm increases linearly with the concentration of peroxynitrite from 0 to 50 μM, and the detection limit is estimated to be 59 nM. Moreover, bioimaging of exogenous and endogenous peroxynitrite in living cells and in vivo detection of peroxynitrite with this probe at dual fluorescence channels were all successfully applied. The results suggest that this new probe can be used as a useful imaging tool for studying peroxynitrite in vitro and in vivo.Graphical abstractImage 1
  • Online profiling of living rat brain extracellular pH using a pH-Dependent
           solid phase extraction scheme coupled with microdialysis sampling and
           inductively coupled plasma mass spectrometry
    • Abstract: Publication date: Available online 15 December 2018Source: Analytica Chimica ActaAuthor(s): Cheng-Kuan Su, Chia-Che Ho In this study, a novel analytical method was developed for online profiling of living rat brain extracellular pH. It involved microdialysis (MD) sampling, introduction of metal ions (e.g., Mn, Co, Ni, Cd) as acid/base indicators, and a pH-dependent solid phase extraction (SPE) based on polymer–metal ion interactions as a sample pretreatment scheme prior to analysis through inductively coupled plasma mass spectrometry (ICP-MS). With a 10-μL microdialysate, optimization of the system provided a working pH range from 5.8 to 8.2 and allowed differentiation of tiny changes in pH, down to a resolution of 0.015 pH units. Standard deviations of measured pH for 6 h of continuous measurement were below 0.05, which was sufficient for evaluating the homeostatic status and the dynamic fluctuations in living rat brain extracellular pH. The method's applicability was verified through measurement of the basal extracellular pH in living rat brains and through monitoring of its changes in response to perfusion of a high-K+ medium. By applying metal ions as acid/base indicators and coupling a pH-dependent SPE scheme with MD sampling and ICP-MS, this method presents an alternative strategy for reliable online profiling of the living rat brain extracellular pH.Graphical abstractImage 1
  • High-resolution mass spectrometry–based multi-residue method covering
           relevant steroids, stilbenes and resorcylic acid lactones in a variety of
           animal-based matrices
    • Abstract: Publication date: Available online 15 December 2018Source: Analytica Chimica ActaAuthor(s): A. Kaufmann, P. Butcher, K. Maden, S. Walker, M. Widmer A new, relatively simple sample processing and detection workflow has been developed for the quantification and confirmation of banned growth-promoting substances in a wide variety of animal-based food products. The method covers all required compounds (belonging to the so-called A1, A3, A4 and B2f groups as termed by the relevant EU legislation) which are currently monitored by the official European community surveillance programs. The sample processing includes a thermal sample denaturation step, intended to prevent undesirable side-reactions during the following enzymatic deconjugation of covalently bound analytes. A pH-adjusted dual liquid/liquid-extraction produces sufficient clean extracts for a wide range of matrices (urine, muscle, liver, serum, full blood). The method has been validated using two hybrid quadrupole high-resolution mass spectrometers (Orbitrap and time-of-flight technology–based instruments). Full-scan data acquisition, interlaced with targeted modes (unit mass isolation of the precursors, followed by collision-induced fragmentation), produces sufficiently sensitive and selective detection of the analytes within all the validated matrices. The proposed method is an alternative to currently used methods that are restricted to a limited set of analytes and matrices.Graphical abstractImage 1
  • Facile Synthesis of Layered Mesoporous Covalent Organic Polymers for
           Highly Selective Enrichment of N-glycopeptides
    • Abstract: Publication date: Available online 14 January 2019Source: Analytica Chimica ActaAuthor(s): Fengjuan Ding, Zhanying Chu, Quanqing Zhang, Haiyan Liu, Weibing Zhang Hydrophilic interaction liquid chromatography is a significant strategy for the separation and enrichment of glycoproteins and glycopeptides. A layered imine-based covalent organic polymer with mesopores (denoted as p-TpBDH) was successfully fabricated by a facile solvothermal method. Then p-TpBDH-OH with abundant hydrophilic groups was evolved from p-TpBDH by the direct reduction. 36 and 40 glycopeptides were identified from IgG digests respectively by p-TpBDH and p-TpBDH-OH. Furthermore, the p-TpBDH-OH exhibits superior selectivity (IgG: BSA=1: 250) for glycopeptides compared with the p-TpBDH. Encouragingly, a total of 463 glycopeptides assigned to 173 glycoproteins were finally identified from only 2 μL human serum by the p-TpBDH-OH. Compared with p-TpBDH, abundant hydrophilic and nitrogen-containing affinity sites of p-TpBDH-OH facilitate effective hydrophilic interaction between the polymeric material and glycopeptides. All the results demonstrate the functionalized hydrophilic covalent organic polymer has great potential in large-scale N-glycoproteomic research.Graphical abstractImage 1
  • Q-graphene-scaffolded covalent organic frameworks as fluorescent probes
           and sorbents for the fluorimetry and removal of copper ions
    • Abstract: Publication date: Available online 9 January 2019Source: Analytica Chimica ActaAuthor(s): Yuanyuan Cai, Yao Jiang, Luping Feng, Yue Hua, Huan Liu, Chuan Fan, Mengyuan Yin, Shuai Li, Xiaoxia Lv, Hua Wang Metal-free fluorescent covalent organic frameworks (COFs) were synthesized initially with Q-Graphene (QG) scaffolds by the one-step covalent reactions of melamine-aldehyde and phenol-aldehyde poly-condensations using paraformaldehyde. It was discovered that onion-like hollow QG, which consists of multi-layer graphene and different carbon allotropes having a high proportion of folded edges and surface defects, could endow the scaffolded COFs with enhanced green fluorescence and environmental stability. Unexpectedly, they could exhibit the powerful absorption for Cu2+ ions resulting in the specific quenching of fluorescence. A fluorimetric strategy with QG-scaffolded COFs was thereby developed to probe Cu2+ ions separately in blood and wastewater with the linear concentration ranges of 0.0010–10.0 μM (limit of detection of 0.50 nM) and 0.0032–32.0 μM (limit of detection of 2.4 nM), respectively, promising the potential applications for the field-applicable monitoring of Cu2+ ions in the clinical and environmental analysis fields. In addition, the prepared COFs sorbents were employed to absorb Cu2+ ions in wastewater showing high removal efficiency. More importantly, such an one-pot fabrication route with hollow QG scaffolds may be tailorable extensively for the preparation of a variety of metal-free multifunctional COFs with enhanced fluorescence, water solubility, environmental stability, and metal removal capability.Graphical abstractImage 1
  • Plasmonic Metal Nanoparticles as Efficient Mass Tags for Ion Signal
           Amplification and Ultrasensitive Detection of Protein Markers
    • Abstract: Publication date: Available online 9 January 2019Source: Analytica Chimica ActaAuthor(s): Yu-Hong Cheng, Yam-Fung Cheung, Toby Siu-Chung Tam, Chun-Nam Lok, Hongzhe Sun, Kwan-Ming Ng The development of sensitive and specific analytical methods is critical for the discovery of molecular biomarkers, which assists disease diagnosis and understanding biological processes. Herein, a highly sensitive method is developed using antibody-conjugated metal nanoparticles for the detection of targeted biomarkers down to low attomole level via coupling of immunoassay techniques with laser ionization mass spectrometry (LI-MS). The conjugated antibodies target specific antigens, while the metal nanoparticles act as mass tags and ion reservoirs for signal amplification. With the characteristic localized surface plasmon resonance (LSPR) properties, gold (AuNPs) and silver nanoparticles (AgNPs) undergo explosive ionization upon laser irradiation to generate abundant characteristic mass reporter ions for strong MS signal amplification. With the antibody-conjugated NPs, detection of trace proteins in various biological samples with complex matrix environments, including urine, cell lysates, and animal tissues was demonstrated.Graphical abstractImage 1
  • Porous SiO2-Coated Au-Ag Alloy Nanoparticles for the Alkyne-mediated
           Ratiometric Raman Imaging Analysis of Hydrogen Peroxide in Live Cells
    • Abstract: Publication date: Available online 9 January 2019Source: Analytica Chimica ActaAuthor(s): Yanmei Si, Lulu Li, Xiaojie Qin, Yaocai Bai, Jishan Li, Yadong Yin We prepared an ultrathin porous silica shell-coated Au-Ag alloy nanoparticle (AuAg@p-SiO2NP) and developed it as a novel alkyne-based surface-enhanced Raman scattering (SERS) nanoprobe for the ratiometric Raman imaging of exogenous and endogenous H2O2 in live cells. The AuAg@p-SiO2NPs functionalized with 4-mercaptophenylboronic acid (MPBA) and 4-mercaptophenylacetylene (MPAE, 1,986 cm-1) as internal standard were first incubated with dopamine (DA) to incorporate the bridging molecules through the formation of borate bond between DA and MPBA on the surface of nanoparticle. Then, the signaling alkyne molecules of 3-(4-(phenylethynyl) benzylthio) propanoic acid (PEB, 2,214 cm-1) were conjugated to the surface of nanoparticle through the formation of amide bond between the carboxyl group on the PEB and the amino group on the DA, forming the ratiometric SERS nanoprobe. In the presence of H2O2, the alkynyl on the PEB is released from the surface of the Au-Ag alloy nanoparticle due to the boronate-to-phenol switch, decreasing the Raman signal at 2,214 cm-1 significantly. Since the Raman signal of MPAE at 1,986 cm-1 remains unchanged, quantitative analysis of H2O2 concentration can be achieved based on the ratiometric value of I1986/I2214. Under the optimized conditions, the plot of the ratiometric value of I1986/I2214 versus the H2O2 concentration in the range from 0.12 to 8 μM revealed a good linear response with a detection limit of 52 nM based on a signal-to-noise ratio of S/N = 3. The porous SiO2-coated Au-Ag alloy nanoparticle provides a novel SERS substrate with excellent biocompatibility, high stability, and effective anti-interference ability. Together with the alkynyl derivatives as internal standard, the SERS nanoprobe reported here allows the ratiometric detection of H2O2 in live cells and can be further applied to quantify many other biomolecules by using different signaling agents.Graphical abstractImage 1
  • Use of MALDI-MS with solid-state hydrogen deuterium exchange for
           semi-automated assessment of peptide and protein physical stability in
           lyophilized solids
    • Abstract: Publication date: Available online 9 January 2019Source: Analytica Chimica ActaAuthor(s): Sneha R. Kabaria, Ian Mangion, Alexey A. Makarov, Gregory F. Pirrone Biological therapeutics are established as major contributors to the pharmaceutical pipeline. Many of these biological drugs are lyophilized to preserve their conformation and reduce decomposition during storage and shipping. Therefore, understanding and controlling the effects of lyophilization on protein higher order structure is critical for commercialization of biologics. Hydrogen Deuterium Exchange Mass Spectrometry (HDX-MS) is a well-established technique for studying protein higher order structure. Previous publications have demonstrated a solid state HDX (ssHDX) method for labeling formulated, lyophilized proteins to assess their physical stability during, but this process still suffered from low throughput and undesired back exchange. Recently, our group described a method combining HDX-MS with MALDI to greatly reduce the time of analysis and nearly eliminate H/D back-exchange, but that method was not suited for interrogating solid samples. This work integrates the two techniques to assess and predict the stability of peptides and proteins following mixing and lyophilization with various excipient formulations. Sample mixing and handling were performed through the use of a bench-top robotics and programmed data MALDI-MS acquisition allowed for monitoring deuterium incorporation for dried peptides and protein samples following continuous labeling with D2O vapor. Effects of excipients upon peptide stability were also tracked and compared to a control for a three day labeling time course. This workflow is automated and free from back-exchange. As demonstrated by deuterium retention of bradykinin, these features serve to reduce experimental error normally associated with conventional deuterium exchange experiments. The proposed union of MALDI-MS and ssHDX can be applied to study higher order structure of proteins and peptides and the effects of added excipients in an environment that closely resembles the storage and shipping conditions of biopharmaceuticals and may be beneficial in giving insights studying protein structural dynamics in solids.Graphical abstractImage 1
  • Y-Shaped DNA-Mediated Hybrid Nanoflowers as Efficient Gene Carriers for
           Fluorescence Imaging of Tumor-Related mRNA in Living Cells
    • Abstract: Publication date: Available online 9 January 2019Source: Analytica Chimica ActaAuthor(s): Xinsheng Yu, Lianzhe Hu, Hui He, Feng Zhang, Min Wang, Weili Wei, Zhining Xia Organic-inorganic hybrid nanomaterial has gained much attention due to its excellent performances in bioanalysis and biomedicine. However, the preparation of DNA-inorganic hybrid nanomaterial with suitable size for cell uptake remains a huge challenge. Herein, a moderate biomineralization strategy for synthesis of Y-DNA@Cu3(PO4)2 (Y-DNA@CuP) hybrid nanoflowers is reported. Y-DNA with a loop structure is used as both the biomineralization template and the recognition unit for thymidine kinase 1 (TK1) mRNA. The Y-DNA probe can linearly response to TK1 mRNA target sequence in a range from 2 nM to 150 nM with the limit of detection as low as 0.56 nM. Interestingly, the presence of Y-DNA significantly decreases the size of Cu3(PO4)2 (CuP) particles, which allows them suitable for intracellular applications as gene nanocarriers. Once inside the cells, the hybrid nanoflowers dissolve and release the Y-DNA probes. Then, the intracellular TK1 mRNA hybridizes with the loop region of Y-DNA, which dissociates the Cy3-labeled loop strand and turns on the red fluorescence. Through the real-time imaging of the intracellular TK1 mRNA, the assessment of tumor cells before and after the treatment of drugs including β-estradiol and tamoxifen is achieved.Graphical abstractImage 1
  • Nucleic acid-based fluorescent methods for the determination of DNA repair
           enzyme activities: A review
    • Abstract: Publication date: Available online 9 January 2019Source: Analytica Chimica ActaAuthor(s): Chang Yeol Lee, Hansol Kim, Ki Soo Park, Hyun Gyu Park DNA repair pathways are closely associated with the maintenance of genomic integrity, disease outbreak, and the development of therapeutics. Owing to these significances, novel analytical methods for enzymes that are involved in the DNA repair pathways have been actively investigated. This review focuses on discussions on nucleic acid-based methods, especially those based on the fluorescence, for the determination of DNA repair enzymes. Furthermore, this review not only provides meaningful insights in creating ingenious fluorescent detection methods but it also suggests future directions that will be followed in developing new analytical technologies for the DNA repair enzymes.Graphical abstractImage 1
  • Nanobody-based binding assay for the discovery of potent inhibitors of
           CFTR inhibitory factor (Cif)
    • Abstract: Publication date: Available online 9 January 2019Source: Analytica Chimica ActaAuthor(s): Natalia Vasylieva, Seiya Kitamura, Jiexian Dong, Bogdan Barnych, Kelli L. Hvorecny, Dean R. Madden, Shirley J. Gee, Dennis W. Wolan, Christophe Morisseau, Bruce D. Hammock Lead identification and optimization are essential steps in the development of a new drug. It requires cost-effective, selective and sensitive chemical tools. Here, we report a novel method using nanobodies that allows the efficient screening for potent ligands. The method is illustrated with the cystic fibrosis transmembrane conductance regulator inhibitory factor (Cif), a virulence factor secreted by the opportunistic pathogen Pseudomonas aeruginosa. 18 nanobodies selective to Cif were isolated by bio-panning from nanobody-phage library constructed from immunized llama. 8 out of 18 nanobodies were identified as potent inhibitors of Cif enzymatic activity with IC50s in the range of 0.3-6.4 μM. A nanobody VHH219 showed high affinity (KD= 0.08nM) to Cif and the highest inhibitory potency, IC50=0.3 μM. A displacement sandwich ELISA (dsELISA) with VHH219 was then developed for classification of synthetic small molecule inhibitors according their inhibitory potency. The developed assay allowed identification of new inhibitor with highest potency reported so far (0.16±0.02 μM). The results from dsELISA assay correlates strongly with a conventional fluorogenic assay (R= 0.9998) in predicting the inhibitory potency of the tested compounds. However, the novel dsELISA is an order of magnitude more sensitive and allows the identification and ranking of potent inhibitors missed by the classic fluorogenic assay method. These data were supported with Octet biolayer interferometry measurements. The novel method described herein relies solely on the binding properties of the specific neutralizing nanobody, and thus is applicable to any pharmacological target for which such a nanobody can be found, independent of any requirement for catalytic activity.Graphical abstractImage 1
  • Analysis of Charged Acrylic Particles by On-line Comprehensive
           Two-Dimensional Liquid Chromatography and Automated Data-Processing
    • Abstract: Publication date: Available online 9 January 2019Source: Analytica Chimica ActaAuthor(s): Bob W.J. Pirok, Noor Abdulhussain, Ton Brooijmans, Tijs Nabuurs, Jens de Bont, Mike A.J. Schellekens, Ron A.H. Peters, Peter J. Schoenmakers A thorough understanding of particle formation and polymer growth during emulsion polymerization is indispensable for the development of particles and products with very specific properties. This has created a demand for the detailed characterization of various properties and property distributions – and the relation between these. A method is described that enables comprehensive, simultaneous determination of the size distribution of nanoparticles and the molecular-weight distribution of the constituting polymers as a function of the particle size. The result is a complete two-dimensional distribution that details the interdependence of the two parameters. The approach comprehensively combines hydrodynamic chromatography with size-exclusion chromatography. An automated band-broadening filter has been developed to improve the accuracy of the measured distributions. The algorithm utilizes automated curve-fitting approaches to describe detected particle distributions for each horizontal slice of the 2D-LC chromatogram, and filters band broadening using calibration curves. The method has been applied to samples of complex nanoparticles comprising hydrophobic, hydrophilic and charged moieties, viz. stabilized dispersions of poly[(methyl methacrylate)-co-(butyl acrylate)-co-(methacrylic acid)]-nanoparticles in water. We consistently found that, within a single population of particles, the weight-average molecular weight increases with particle size.Graphical abstractImage 1
  • Determination of prostate cancer biomarker acid phosphatase at a copper
           phthalocyanine-modified screen printed gold transducer
    • Abstract: Publication date: Available online 9 January 2019Source: Analytica Chimica ActaAuthor(s): Zina Fredj, Mounir Ben Ali, Mohammed Nooredeen Abbas, Eithne Dempsey In this work, a novel sensor based on immobilized copper phthalocyanine, 2,9,16,23-tetracarboxylic acid-polyacrylamide (Cu(II)TC Pc-PAA) was developed for determination of acid phosphatase (ACP) levels in nanomolar quantities. Detection was based on the measurement of enzymatically generated phosphate, with initial studies focused on phosphate detection at a Cu(II)TC Pc-PAA modified screen-printed gold transducer. The sensor was characterised in relation to operational performance (pH, response time, stability, linearity, and sensitivity) and common anionic interferents (nitrate, sulphate, chloride, and perchlorate). The functionalised surface also facilitated rapid detection of the enzyme bi-product 2-naphthol over the range 5-3000 μM. Quantitation of ACP was demonstrated, realising a linear response range of 0.5-20 nM and LOD of 0.5 nM, which is within the clinical range for this prostate cancer biomarker.Graphical abstractImage 1
  • DeepSpectra: An end-to-end deep learning approach for quantitative
           spectral analysis
    • Abstract: Publication date: Available online 8 January 2019Source: Analytica Chimica ActaAuthor(s): Xiaolei Zhang, Tao Lin, Jinfan Xu, Xuan Luo, Yibin Ying Learning patterns from spectra is critical for the development of chemometric analysis of spectroscopic data. Conventional two-stage calibration approaches consist of data preprocessing and modeling analysis. Misuse of preprocessing may introduce artifacts or remove useful patterns and result in worse model performance. An end-to-end deep learning approach incorporated Inception module, named DeepSpectra, is presented to learn patterns from raw data to improve the model performance. DeepSpectra model is compared to three CNN models on the raw data, and 16 preprocessing approaches are included to evaluate the preprocessing impact by testing four open accessed visible and near infrared spectroscopic datasets (corn, tablets, wheat, and soil). DeepSpectra model outperforms the other three convolutional neural network models on four datasets and obtains better results on raw data than in preprocessed data for most scenarios. The model is compared with linear partial least square (PLS) and nonlinear artificial neural network (ANN) methods and support vector machine (SVR) on raw and preprocessed data. The results show that DeepSpectra approach provides improved results than conventional linear and nonlinear calibration approaches in most scenarios. The increased training samples can improve the model repeatability and accuracy.Graphical abstractImage 1
  • Colorimetric detection of normetanephrine, a pheochromocytoma biomarker,
           using bifunctionalised gold nanoparticles
    • Abstract: Publication date: Available online 8 January 2019Source: Analytica Chimica ActaAuthor(s): Tania M. Godoy-Reyes, Ana M. Costero, Pablo Gaviña, Ramón Martínez-Máñez, Félix Sancenón A simple and effective colorimetric method for the detection of normetanephrine (NMN), an O-methylated metabolite of norepinephrine, using functionalised gold nanoparticles is described. This metabolite is an important biomarker in the diagnosis of adrenal tumours such as pheocromocytoma or paraganglioma. The colorimetric probe consists of spherical gold nanoparticles (AuNPs) functionalized with two different ligands, which specifically recognize different functional groups in normetanephrine. Thus, a benzaldehyde-terminated ligand was used for the recognition of the amino alcohol moiety in NMN, by forming the corresponding oxazolidine. On the other hand, N-acetyl-cysteine was chosen for the recognition of the phenolic hydroxyl group through the formation of hydrogen bonds. The selective double molecular recognition between the probe and the hydroxyl and the amino-alcohol moieties of normetanephrine led to interparticle-crosslinking aggregation resulting in a change in the color of the solution, from red to blue, which could be observed by naked eye. The probe was highly selective towards normetanephrine and no color changes were observed in the presence of other neurotransmitter metabolites such as homovanillic acid (HVA) (dopamine metabolite), 5-hydroxyindoleacetic acid (5-HIAA) (serotonin metabolite), or other biomolecules present in urine such as glucose (Glc), uric acid (U.A), and urea. Finally, the probe was evaluated in synthetic urine with constituents that mimic human urine, where a limit of detection of 0.5 μM was achieved.Graphical abstractImage 1
  • Electrochemical paper based cancer biosensor using iron oxide
           nanoparticles decorated PEDOT:PSS
    • Abstract: Publication date: Available online 8 January 2019Source: Analytica Chimica ActaAuthor(s): Saurabh Kumar, Mohammad Umar, Anas Saifi, Suveen Kumar, Shine Augustine, Saurabh Srivastava, Bansi D. Malhotra We report results of the studies relating to the fabrication of a label-free, flexible, light weight and disposable conducting paper based immunosensing platform comprising of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and nanostructured iron oxide (nFe2O3@PEDOT:PSS) nanocomposite for detection of carcinoembryonic antigen (CEA), a cancer biomarker. The effect of various solvents such as sorbitol, ethanol, propanol, n-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO) on the electrical conductivity of Whatman filter paper (WP) modified with nFe2O3@PEDOT:PSS/WP was investigated. The electrical conductivity of the PEDOT:PSS/WP electrode was found to be enhanced by two orders of magnitude (from 6.8 x 10-4 to 1.92 x 10-2 Scm-1) after its treatment with DMSO. Further, nFe2O3 doped PEDOT:PSS/WP electrode exhibited the electrical conductivity as 2.4 x 10-2 Scm-1. Besides this, the incorporation of iron oxide nanoparticles (nFe2O3) into PEDOT:PSS/WP resulted in improved electrochemical performance and signal stability. This nFe2O3@PEDOT:PSS/WP based platform was used for immobilization of the anti-carcinoembronic antigen (anti-CEA) protein for quantitative estimation of cancer biomarker (CEA). The results of electrochemical response studies revealed that this conducting paper based immunoelectrode had a sensitivity of 10.2 μAng-1mLcm-2 in the physiological range (4-25 ngmL-1) and shelf life of 34 days. Further, the proposed immunoelectrode was validated with conventional ELISA for the detection of CEA in serum samples of cancer patients.Graphical abstractImage 1
  • Cultivar Differentiation of Citri Reticulatae Pericarpium by a Combination
           of Hierarchical Three-step Filtering Metabolomics Analysis, DNA barcoding
           and Electronic Nose
    • Abstract: Publication date: Available online 8 January 2019Source: Analytica Chimica ActaAuthor(s): Shang-Zhen Li, Su-Ling Zeng, Yan Wu, Guo-Dong Zheng, Chu Chu, Qiang Yin, Bai-Zhong Chen, Ping Li, Xu Lu, E-Hu Liu The traditional Chinese medicine Citri Reticulatae Pericarpium (CRP) was mainly originated from the dried pericarp of Citrus reticulata ‘Chachi’ (Crc), Citrus reticulata ‘Dahongpao’ (Crd), Citrus reticulata ‘Unshiu’ (Cru) and Citrus reticulata ‘Tangerina’ (Crt) in China. Since these four cultivars have great similarities in morphology, reliable methods to differentiate CRP cultivars have rarely been reported. To discriminate the differences of these CRP cultivars, herein an efficient and reliable method by combining metabolomics, DNA barcoding and electronic nose was first established. The hierarchical three-step filtering metabolomics analysis based on liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) indicated that 9 species-specific chemical markers including 6 flavanone glycosides and 3 polymethoxyflavones could be considered as marker metabolites for discrimination of the geoherb Crc from other cultivars. A total of 19 single nucleotide polymorphism (SNP) sites were found in nuclear internal transcribed spacer 2 (ITS2) of CRP, and three stable SNP sites (33, 128 and 174) in the ITS2 region can distinguish the four CRP cultivars. The electronic nose coupled with chemometrics could also be used to effectively distinguish Crc from other CRP cultivars. Therefore, our results indicated that the integrated method will be an effective strategy for discrimination of similar herbal medicines.Graphical abstractImage 1
  • Label-free fluorometric assay for cytochrome c in apoptotic cells based on
           near infrared Ag2S quantum dots
    • Abstract: Publication date: Available online 8 January 2019Source: Analytica Chimica ActaAuthor(s): Meifang Cai, Caiping Ding, Xuanyu Cao, Fangfang Wang, Cuiling Zhang, Yuezhong Xian As an important biomarker, cytochrome c (Cyt c) plays a crucial role in mitochondrial electron transport chain and cell apoptosis. Herein, a label-free near-infrared (NIR) Ag2S quantum dots (QDs)-based fluorescent strategy was constructed for the sensitive and selective detection of Cyt c. In this system, Cyt c was hydrolyzed by trypsin, and the resulting heme-peptide fragment exhibited peroxidase-like activity for catalytic decomposition of H2O2 into hydroxyl radical (·OH). The presence of caffeic acid in this system resulted into the formation of caffeic acid-quinone due to the strong oxidizing ability of ·OH. The production of caffeic acid-quinone led to the fluorescence quenching of Ag2S QDs through electron transfer mechanism. Based on the cascade reaction, we successfully developed a label-free approach to detect Cyt c using Ag2S QDs as nanoprobes. Under the optimized conditions, the fluorescence intensity of Ag2S QDs was linearly relative to the concentration of Cyt c over the range from 2.0 to 150 nM with a detection limit of 1.7 nM. In addition, this strategy was successfully applied for quantitative detection of Cyt c in cell lysates of H2O2 or etoposide (anticancer drug)-induced apoptotic cells, providing great potential application for cell-based oxidation pressure determination and screening of anticancer drugs.Graphical abstractA label-free near-infrared (NIR) Ag2S quantum dots (QDs)-based fluorescent strategy was constructed for the sensitive and selective detection of Cyt c.Image 1
  • Fast Determination of Extra-Virgin Olive Oil Acidity by Voltammetry and
           Partial Least Squares Regression
    • Abstract: Publication date: Available online 4 January 2019Source: Analytica Chimica ActaAuthor(s): M. Antonietta Baldo, Paolo Oliveri, Sabrina Fabris, Cristina Malegori, Salvatore Daniele In this paper, an approach for the detection of extra-virgin olive oil (EVOO) free-acidity, based on combination of voltammetric profiles (Voltammetry) and Partial Least Squares (PLS) multivariate regression, is described. Voltammetric measurements are performed with a 12.5 μm radius platinum microdisk, directly in the oil samples mixed with 0.5 M of the room temperature ionic liquid (RTIL) tri-hexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, which acted as a supporting electrolyte, and allows achieving a suitable conductivity in the matrices. Multivariate regression is performed directly on full voltammetric responses recorded over a properly chosen negative potential range and scan rate, where essentially all free fatty acids, characterizing EVOOs, can be reproducibly reduced. PLS regression models are built by employing Italian EVOO samples training sets at different acidity levels (over the range 0.2 % w/w - 1.5 % w/w; (% w/w) represents mass percentage) and optimized by choosing the optimal complexity, in terms of number of latent variables (LVs). The free-acidity prediction is made through a multivariate model, constructed by using standards of known acidity (determined by the official volumetric titration method) and validated on an external sample set. To show the validity of the proposed method, the PLS/Voltammetry predictions of the free-acidity of a series of commercially available Italian EVOOs, ranging from 0.2 to 0.41 %w/w, are obtained and the values compared with those determined by the official titration approach. Differences found between the two methods are within 5% RSD.Graphical abstractImage 1
  • A new lysosome-targetable fluorescent probe with a large Stokes shift for
           detection of endogenous hydrogen polysulfides in living cells
    • Abstract: Publication date: Available online 2 January 2019Source: Analytica Chimica ActaAuthor(s): Yanshen Ren, Lulu Zhang, Ziyan Zhou, Suilou Wang, Yueqing Gu, Yungen Xu, Xiaoming Zha Hydrogen polysulfides (H2Sn, n>1) influence a variety of important biological functions and activities associated with hydrogen sulfide (H2S). The development of probes for rapid, selective, and sensitive detection of H2Sn still remains a great challenge. Lysosome plays crucial roles in various physiological processes among living cells, which arouse high interest in detecting endogenous lysosome-targetable H2Sn. To the best of our knowledge, there is no lysosome-targetable probe for H2Sn has been reported. In this work, a new lysosome-targetable probe NIPY-NF, based on the scaffold of imidazo[1,5-]pyridine, with a large Stokes shift (215 nm), low detection limit (84 nM), fast response time (6 min) and low cytotoxicity was designed and synthesized. Furthermore, NIPY-NF was successfully applied into the cell imaging for detection of endogenous lysosome-targetable H2Sn.Graphical abstractImage 1
  • Image-guided Cancer Therapy Using Aptamer-functionalized Cross-linked
           Magnetic-Responsive Fe3O4@Carbon Nanoparticles
    • Abstract: Publication date: Available online 2 January 2019Source: Analytica Chimica ActaAuthor(s): Changhong Zhao, Xuebin Song, Weiguang Jin, Fan Wu, Qicheng Zhang, Ninglin Zhou, Ming Zhang, Jian Shen The excellent anticancer effect of combined differential cancer therapies has been observed in the last few decades. Efficient theragnostic nanoparticles (NPs) for malignancy treatment have received considerable research attention and widely investigated today. This study presents our results on the development of aptamer-functionalized Fe3O4@carbon@doxorubicin NPs (Apt-Fe3O4@C@DOX) and their application in the synergetic chemo–photothermal therapy (PTT) of cancer. The Apt-Fe3O4@C@DOX NPs displayed high photothermal conversion efficiency and extensive pH/heat-induced drug release. In vitro (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide experiments indicated that the combined chemo–PTT is much more toxic toward lung adenocarcinoma cells (A549) than PTT or chemotherapy alone. In addition, the Apt-Fe3O4@C@DOX NPs demonstrated decreasing contrast enhancement of magnetic resonance (MR) signals, which means they may be potentially applied as a contrast agent and serve as a critical component of T2-weighted MR imaging of tumor tissues. Taking the results together, the Apt-Fe3O4@C@DOX NPs show great potential for cancer therapy.Graphical abstractSchematic illustration for the preparation of Aptamer-Functionalized Cross-Linked Magnetic-Responsive Fe3O4@Carbon Nanoparticles (Apt-Fe3O4@C@DOX NPs) with tumor-triggered targeting property.Image 1
  • Spatially resolved analysis of liquid crystal displays by laser
           ablation-atmospheric pressure chemical ionization-mass spectrometry
    • Abstract: Publication date: Available online 2 January 2019Source: Analytica Chimica ActaAuthor(s): Jennifer-Christin Müller, Tanja Berg, Claudia Enders, Peter Leonhard, Uwe Karst In recent years, liquid crystal displays (LCDs) became more and more popular in industrial and consumer electronics applications. Unevenly distributed liquid crystals (LC) and the presence of organic contaminations in the LC layer, for example from the display sealant, can cause display defects and therefore lower the display quality. This work describes the development of a fast and easy screening method for display samples by laser ablation coupled to atmospheric pressure chemical ionization-mass spectrometry (LA-APCI-MS). With this ambient technique, LC components as well as sealant materials, which are one of the main sources for display contaminations, can be detected simultaneously using spatial resolutions down to 100 μm. Minimal sample preparation is needed for this method and exact masses can be acquired by using an Orbitrap mass analyzer. By LA-APCI-MS, nineteen different LCs and five different sealant materials were detected as pure substances as well as on commercially available LCDs. In addition, a principle component analysis (PCA) was used to differentiate between LCs and sealant ions in the complex data matrix.Graphical abstractImage 1
  • An efficient thin-walled Pd/polypyrrole hybrid nanotube biocatalyst for
           sensitive detection of ascorbic acid
    • Abstract: Publication date: Available online 2 January 2019Source: Analytica Chimica ActaAuthor(s): Mengxiao Zhong, Maoqiang Chi, Yun Zhu, Ce Wang, Xiaofeng Lu Controllable fabrication of novel and uniform noble metal nanoparticles on a specific support with a superior catalytic or electrocatalytic performance is of significantly importance for practical applications. In this report, we demonstrated an effective way to fabricate uniform thin-walled Pd/polypyrrole (PPy) hollow nanotubes. The prepared Pd/PPy hybrid nanotubes exhibited an excellent peroxidase-like activity to oxidize a typical peroxidase substrate such as 3,3′,5,5′-tetramethylbenzidine in comparison with traditional Pd/C and Pd black catalysts. The outstanding catalytic activity of the Pd/PPy hybrid nanotubes for peroxidase mimicking could be resulting from their unique hollow characteristic and aninterfacial effect between PPy and Pd components. Based on the favorable catalytic property of the Pd/PPy hybrid nanotubes, a convenient and rapid colorimetric way to sensitively determine ascorbic acid has been presented. The detection limit was around 0.062 μM and an excellent selectivity was also achieved. The developed detection system in this study could be extended to the fields of bioscience and biotechnology with promising prospects.Graphical abstractImage 1
  • Poly(deep eutectic solvent)-functionalized magnetic metal-organic
           framework composites coupled with solid-phase extraction for the selective
           separation of cationic dyes
    • Abstract: Publication date: Available online 2 January 2019Source: Analytica Chimica ActaAuthor(s): Xiaoxiao Wei, Yuzhi Wang, Jing Chen, Panli Xu, Wei Xu, Rui Ni, Jiaojiao Meng, Yigang Zhou Novel polymeric deep eutectic solvents (PDES) based on 3-acrylamidopropyl trimethylammonium chloride/D-sorbitol functionalized amino-magnetic (Fe3O4-NH2) metal-organic framework (HKUST-1-MOF) composites (Fe3O4-NH2@HKUST-1@PDES) were synthesized and characterized by field emission transmission electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM) and zeta potentials. Then the composites were firstly utilized to selectively separate malachite green (MG) and crystal violet (CV) coupled with magnetic solid-phase extraction (MSPE). A response surface methodology (RSM) based on Latin hypercube sampling (LHS) was selected to analytically optimize the extraction parameters including initial concentration of dyes, extraction time, pH value and extraction temperature. The maximum extraction amount and optimal extraction conditions predicted by the RSM model matched well with the actual experimental results, and the extraction amount was 966.93 mg·g-1 for MG and 788.90 mg·g-1 for CV,respectively. The results indicated that the model possessed higher calculation accuracy through analyzing fewer sample points, thereby achieving theoretical prediction of extraction amount and conditions and being a prefect supplementary to actual experiments. The electrostatic interaction between the composites and cationic dyes played the main roll in the extraction process. The proposed extraction method exhibited lower limit of detection (98.19 ng·mL-1 for MG and 23.97 ng·mL-1 for CV) and preeminent precision (RSD ˂ 0.4%). Spiked recoveries of fish samples at three spiking levers ranged from 89.43% to 100.65% for MG and 95.29% to 98.03% for CV. All results highlighted the excellent potential of Fe3O4-NH2@HKUST-1@PDES-MSPE strategy in selective separation of cationic dyes in complex medium.Graphical abstractFabrication of Fe3O4-NH2@HKUST-1@PDES composites and its application in MSPE of malachite green and crystal violet.Image 1
  • Sub-femtomolar detection of HIV-1 gene using DNA immobilized on composite
           platform reinforced by a conductive polymer sandwiched between two
           nanostructured layers: A solid signal-amplification strategy
    • Abstract: Publication date: Available online 29 December 2018Source: Analytica Chimica ActaAuthor(s): Mojtaba Shamsipur, Leila Samandari, Avat (Arman) Taherpour, Afshin Pashabadi This study introduces a signal amplification strategy rely on incorporating a specific polymer film between two typical nanostructured layers, aiming to improve the electrical properties of the platform to be able to transduce small binding event through sub-femtomolar detection of HIV-1 gene at the surface of the constructed biosensing device. The proposed composite was arrayed based on a conductive layer consist of p-aminobenzoic acid (PABA) sandwiched between the electrochemically reduced graphene oxide (ERGO) as the sub-layer, and the gold nanoparticles (AuNPs) as the interfacial layer. We computationally explored that how the use of such design enables the platform to transduce small changes in the interfacial properties of the biosensor, caused by low concentrations of HIV-1 gene, without needing any amplification strategy. Furthermore, it was found that the loin PABA conductive polymer sandwiched between two nanostructure layers play an artwork-ensemble role, which resulted in a good signal repeatability and stability during the relatively long successive incubation and detection procedures. The justification of using such an array of conductive layers was established on the attaining extra low-level of detection limit. The observed performance for probe-DNA immobilized on glassy carbon electrode (GC) modified with ERGO/PABA/AuNPs compared to the GC electrode modified with ERGO/AuNPs inspired us to perform computational calculations, a hybrid of ab-initio and semi-empirical quantum mechanics methods, to discover its probable molecular-scale reasons. A rapid single frequency impedance measurement (SFIM) was also employed to remarkably reduce the measurement time and diminish the probable nonspecific impedance changes. The proposed biosensor was used to evaluate the DNA target over an extremely wide concentration range from 0.1 fM to 10 nM, with a detection limit of 37 aM (S/N = 3).Graphical abstractImage 1
  • Quantum Dot Modified Interface for Electrochemical Immunosensing of
           Procalcitonin for the Detection of Urinary Tract Infection
    • Abstract: Publication date: Available online 28 December 2018Source: Analytica Chimica ActaAuthor(s): Aditya Sharma Ghrera An electrochemical immunoelectrode is fabricated and investigated for quantification of the Procalcitonin (PCT), a protein over expressed in urinary tract infection (UTI). The sensor electrode is prepared by self assembling the conjugate of Zinc sulfide capped Cadmium selenide quantum dots (QD) and PCT specific monoclonal antibody (MAb) over the indium-tin-oxide (ITO) coated glass substrate. The presence of QD in the conjugate is found to provide more electroactive surface area and improved electron transfer kinetics and diffusion coefficient to the immunoelectrode. The electrochemical characteristics of this immunoelectrode towards synthetic PCT sample reveal specificity among the pool of various analytes. The sensing characteristics reveal that the sensor can potentially detect PCT over a concentration of 0.21 ng/mL which is above pathological range in healthy person. However, in absence of QD, the detection range lies in between 0.1 μg/ml to 10 μg/ml, which is far above the expressed concentration of PCT in UTI. Under optimal conditions, the QD based immunoelectrode exhibited good calibration range from 1ng/ml to 10 μg/ml.Graphical abstractImage 1
  • Development and Validation of a Fully Automated Solid-Phase
           Microextraction High Throughput Method for Quantitative Analysis of
           Multiresidue Veterinary Drugs in Chicken Tissue
    • Abstract: Publication date: Available online 28 December 2018Source: Analytica Chimica ActaAuthor(s): Abir Khaled, Emanuela Gionfriddo, Vinicius Acquaro, Varoon Singh, Janusz Pawliszyn This paper presents the development and validation of a fully automated, high-throughput multiclass, multiresidue method for quantitative analysis of 77 veterinary drugs in chicken muscle via direct immersion solid phase microextraction (DI-SPME) and ultra-high pressure liquid chromatography-electrospray ionization - tandem mass spectrometry (UHPLC-ESI-MS/MS). The selected drugs represent more than 12 different classes of drugs characterized by varying physical and chemical properties. A Hydrophilic–lipophilic balance (HLB)/polyacrylonitrile (PAN) extraction phase, prepared using HLB particles synthesized in-house, yielded the best extraction/desorption performance among four different SPME extraction phases evaluated in the current work. The developed SPME method was optimized in terms of SPME coating and geometry, desorption solvent, extraction and rinsing conditions, and extraction and desorption times. Multivariate analysis was performed to determine the optimal desorption solvent for the proposed application. The developed method was validated according to the Food and Drug Administration (FDA) guidelines, taking into account Canadian maximum residue limits (MRLs) and US maximum tolerance levels for veterinary drugs in meat. Method accuracy ranged from 80 to 120% for at least 73 compounds, with relative standard deviation of 1 to 15%. Inter-day precision ranged from 4–15% for 70 compounds. Determination coefficients values were higher than 0.991 for all compounds under study with no significant lack of fit (p> 0.05) at the 5% level. In terms of limits of quantitation, the method was able to meet both Canadian and US regulatory levels for all compounds under study.Graphical abstractImage 1
  • Homogeneous peptide-break assay for luminescent detection of enzymatic
           protein post-translational modification activity utilizing charged
    • Abstract: Publication date: Available online 28 December 2018Source: Analytica Chimica ActaAuthor(s): Kari Kopra, Natalia Tong-Ochoa, Mari Laine, Ville Eskonen, Päivi J. Koskinen, Harri Härmä We have developed a rapid and sensitive universal peptide-based time-resolved luminescence assay for detection of enzymatic post-translational modifications (PTMs). PTMs play essential roles in intracellular signaling and cell regulation, thus providing functional protein diversity in cell. Due this, impaired PTM patterns have been linked to multiple disease states. Clear link between PTMs and pathological conditions have also driven assay development further, but still today most of the methodologies are based on single-specificity or group-specific PTM-recognition. We have previously introduced leuzine-zipper based peptide-break technology as a viable option for universal PTM detection. Here, we introduce peptide-break technology utilizing single-label homogeneous quenching resonance energy transfer (QRET) and charge-based peptide-peptide interaction. We demonstrate the functionality of the new assay concept in phosphorylation, deacetylation, and citrullination. In a comparable study between previously introduced leucine-zipper and the novel charge-based approach, we found equal PTM detection performance and sensitivity, but the peptide design for new targets is simplified with the charged peptides. The new concept allows the use of short < 20 amino acid peptides without limitations rising from the leucine-zipper coiled-coil structure. Introduced methodology enables wash-free PTM detection in a 384-well plate format, using low nanomolar enzyme concentrations. Potentially, the peptide-break technique using charged peptides may be applicable for natural peptide sequences directly obtained from the target protein.Graphical abstractImage 1
  • Developed magnetic multiporous 3D N-Co@C/HCF as efficient sorbent for the
           extraction of five trace phthalate esters
    • Abstract: Publication date: Available online 27 December 2018Source: Analytica Chimica ActaAuthor(s): Yang Wang, Yao Tong, Xu Xu, Lei Zhang A three-dimensional (3D) magnetic porous N-Co@carbon dodecahedron/hierarchical carbon framework (3D N-Co@C/HCF) hybrid has been successfully synthesized by integration of the ZIF-67 into HCF and then calcination under an inert gas (N2). 3D N-Co@C/HCF as magnetic sorbent show good extraction ability for phthalate esters (PAEs: dibutyl phthalate (DBP), dimethyl phthalate (DMP), dicyclohexyl phthalate (DCHP), butyl benzyl phthalate (BBP), diethyl phthalate (DEP)). This is attributed not only to the abundant adsorption sites (due to the presence of large specific surface area) and the extremely strong π-conjugated system of 3D N-Co@C/HCF, but also to sufficient contact spaces and facile transport channels (ascribe to the interconnected hierarchical 3D porous structure) between targets and the material. Furthermore, 3D N-Co@C/HCF possesses excellent magnetism and structure stability for maximizing reuse of sorbent, which is applied as sorbent for disperse magnetic solid-phase extraction (d-MSPE) of five PAEs in the real samples. Under optimized condition, a facile d-MSPE coupled to HPLC-UV detection was developed for the extraction and determination of trace PAEs in real samples. This method revealed a high enhancement factor (230-281), wide linear range (0.2-100 ng mL−1), lower the limits of detection (0.023-0.113 ng mL−1) and satisfactory recoveries (87.1–107.2%) with the relative standard deviation (RSD) (n=5) less than 6% for the determination of PAEs in real samples.Graphical abstractImage 1
  • Nanoraspberry-like copper/ reduced graphene oxide as new modifier for
           simultaneous determination of benzenediols isomers and nitrite
    • Abstract: Publication date: Available online 26 December 2018Source: Analytica Chimica ActaAuthor(s): Najmeh Sabbaghi, Meissam Noroozifar In this study, immobilized nanoraspberry-like copper on the reduced graphene oxide (NRCu-rGO) was synthesized and used for modification of glassy carbon electrode (GCE) for selective and sensitive simultaneous determination of benzenediols isomers; hydroquinone (HQ), catechol (CC), resorcinol (RS) as well as nitrite (NO2-). A detailed investigation such as field emission scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction as well as electrochemistry methods such as cyclic voltammetry, electrochemical impedance spectroscopy, differential pulse voltammetry (DPVs) and chronoamperometry are performed in order to elucidate the preparation process and properties of the NRCu-rGO/GCE. DPVs peak currents increased linearly with the analytes concentrations within the ranges of 0.13 -131.5 μM for HQ, CC, RS and 0.3 -131.5 μM for NO2- with a detection limits 49, 52, 60 and 100 nM for HQ, CC, RS and NO2-, respectively. The proposed modified electrode was successfully used for simultaneous determination of HQ, CC, RS and NO2- in real samples.Graphical abstractImage 1
  • New passive sampling device for effective monitoring of pesticides in
    • Abstract: Publication date: Available online 24 December 2018Source: Analytica Chimica ActaAuthor(s): Eduard F. Valenzuela, Helvécio C. Menezes, Zenilda L. CardealABSTRACTThe extensive use of pesticides promotes environmental contamination, mainly in surface and ground waters. However, they remain at very low concentration and present wide degradation level requiring the use of efficient devices for pesticides passive sampling. In this study, a new in situ passive sampling device was developed for monitoring and estimating time-weighted average (TWA) of pesticides in waters. The device was made with simple, recyclable and cheap materials. The sampling system involves the liquid phase microextraction technique with hollow fiber in two-phases mode. Pesticides determination was done by gas chromatography coupled to mass spectrometry. The method was optimized and validated for the determination of 29 pesticides in water, showing good linearity in the range between 0.012 and 40.00 μg L-1 with determination coefficients of R2> 0,9649. Limit of detection (LOD) ranged from 0.009 to 0.557 μg L-1 and limit of quantification (LOQ) from 0.012 to 0.802 μg L-1. The recoveries of spiked pesticides in water samples were in the range from 96 to 130%. The method was applied to forty environmental water samples collected at São Francisco river basin, Brazil. The highest detection frequency was found for the pesticides 4,4-DDE, 4,4-DDD and propazine. They were detected in more than 20 percent of the samples.Graphical abstractImage 1
  • Smartphone-Based Fluorescent Lateral Flow Immunoassay Platform for Highly
           Sensitive Point-of-Care Detection of Zika Virus Nonstructural Protein 1
    • Abstract: Publication date: Available online 23 December 2018Source: Analytica Chimica ActaAuthor(s): Zhen Rong, Qiong Wang, Nanxi Sun, Xiaofei Jia, Keli Wang, Rui Xiao, Shengqi Wang Simple, inexpensive, and rapid diagnostic tests in low-resource settings with limited laboratory equipment and technical expertise are instrumental in reducing morbidity and mortality from epidemic infectious diseases. We developed a smartphone-based fluorescent lateral flow immunoassay (LFIA) platform for the highly sensitive point-of-care detection of Zika virus nonstructural protein 1 (ZIKV NS1). An attachment was designed and 3D-printed to integrate the smartphone with external optical and electrical components, enabling the miniaturization of the instrument and reduction in cost and complexity. Quantum dot microspheres were utilized as probes in fluorescent LFIA because of their extremely bright fluorescence signal. This approach can achieve quantitative point-of-care detection of ZIKV NS1 within 20 min. Limits of detection (LODs) in buffer and serum were 0.045 and 0.15 ng mL-1, respectively. Despite the high structural similarity, a high-level Dengue virus NS1 as interferent showed limited cross-reactivity. Furthermore, this assay was successfully applied to detecte ZIKV NS1 and virions spiked in complex biological samples, indicating its practical application capability. Given its low cost, compact size, and excellent analytical performance, the proposed smartphone-based fluorescent LFIA platform holds considerable potential in rapid and accurate point-of-care detection of ZIKV NS1 and provides new insight into the design and application of molecular diagnostic methods in low-resource settings.Graphical abstractImage 1
  • Derivatization enhances analysis of estrogens and their bioactive
           metabolites in human plasma by liquid chromatography tandem mass
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Nina Denver, Shazia Khan, Ioannis Stasinopoulos, Colin Church, Natalie ZM. Homer, Margaret R. MacLean, Ruth Andrew Estrogens regulate many diverse biological processes in health and disease. They circulate at a wide range of concentrations in females generating several active metabolites (hydroxy and methoxyestrogens). The metabolites are assumed to be in much lower levels and are thought to contribute to diseases such as pulmonary arterial hypertension (PAH). Estrogen metabolites are challenging to quantify in plasma and currently available immunoassays are non-specific. Here we have developed and validated a novel assay to simultaneously quantify parent estrogens and their metabolites by mass spectrometry (MS).Estrogens were extracted from human plasma using solid phase extraction and derivatized using 1-(5-fluoro-2, 4-dinitrophenyl)-4-methylpiperazine (PPZ) before quaternization by methylation (“MPPZ”). MPPZ derivatives were separated and quantified by liquid chromatography tandem MS (LC-MS/MS) in positive electrospray ionization mode, using a QTrap 6500+ coupled to a Shimadzu Nexera X2. Separation was achieved using an ACE Excel 2 C18-PFP column (2 μm, 2.1 mm x 150 mm). The limits of quantification (LOQ) were 0.43 - 2.17 pg on column with a linear range from 1 or 5 -1000 pg/sample. Intra and inter-day precision and accuracy were acceptable (
  • Specific and simultaneous detection of micro RNA 21 and let-7a by rolling
           circle amplification combined with lateral flow strip
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Mengdi Yao, Xuefei Lv, Yulin Deng, Madiha Rasheed Owing to the pivotal function in post transcriptional gene modification, miRNA biomarkers are playing crucial role in tracking and diagnosing various forms of tumors in a short time period. Hence, the need to develop simple, sensitive and specific detection of miRNAs for precise diagnosis arises. This current study is aimed to develop a detecting platform by combining rolling circle amplification with AuNps-based lateral flow strip (LFS-RCA) for simultaneous detection of miRNA 21 and miRNA let-7a. The current methodology is simple, sensitive, specific and selective for miRNA let-7a and miRNA 21 with the limits of detection (LOD) as low as 20 pM and 40 pM, respectively. In this technique, rolling circle amplification is playing an essential role in increasing sensitivity and reducing experimental cost. Moreover, the padlock probe with high specificity can immediately identify the simultaneous amplification of multiple miRNAs targets, which may contribute in saving sample volume and detection time. Hopefully, in future with further development, this developed technique can be chosen as a potential tool for detection of miRNAs in clinical diagnosis.Graphical abstractImage 1
  • Rapid Pre-Concentration of Mercury in Solids and Water for Isotopic
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): S.E. Janssen, R.F. Lepak, M.T. Tate, J.M. Ogorek, J.F. DeWild, C.L. Babiarz, J.P. Hurley, D.P. Krabbenhoft The precise quantification of mercury (Hg) stable isotope compositions in low concentration or dilute samples poses analytical challenges due to Hg mass limitations. Common Hg pre-concentration procedures require extended processing times, making rapid Hg stable isotope measurements challenging. Here we present a modified pre-concentration method that combines commonly used Hg reduction and gold trap amalgamation followed by semi-rapid thermal desorption (less than 1 hour) and chemical trapping. This custom designed system was demonstrated to perform adequately on multiple trapping matrices including a new bromine monochloride (BrCl) wet oxidant trap (40% 3HNO3:BrCl), capable of trapping consistently in 2mL volume over a wide range of Hg masses (5 to 200 ng). The procedure was also shown to work effectively on natural matrices, waters and sediments, producing comparable isotope results to the direct digestion analyses. Here we present a method that can effectively triple sample throughput in comparison to traditional procedures, and also access lower concentration matrices without compromising the accuracy or precision of Hg isotope measurements.Graphical abstractImage 1
  • Rapid and specific detection of Salmonella infections using chemically
           modified nucleic acid probes
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Isabel Machado, Victoria Garrido, Luiza I. Hernandez, Juliana Botero, Nora Bastida, Beatriz San-Roman, María-Jesús Grilló, Frank J. HernandezABSTRACTSalmonella is a leading source of bacterial foodborne illness in humans, causing gastroenteritis outbreaks with bacteraemia occurrences that can lead to clinical complications and death. Eggs, poultry and pig products are considered as the main carriers of the pathogenic Salmonella for humans. To prevent this relevant zoonosis, key changes in food safety regulations were undertaken to improve controls in the food production chain. Despite these measures, large outbreaks of salmonellosis were reported worldwide in the last decade. Thus, new strategies for Salmonella detection are a priority for both, food safety and public health authorities. Such detection systems should provide significant reduction in diagnostic time (hours) compared to the currently available methods (days). Herein, we report on the discovery and characterization of nucleic acid probes for the sensitive and specific detection of live Salmonella within less than 8 hours of incubation. We are the first to postulate the nuclease activity derived from Salmonella as biomarker of infection and its utility to develop innovative detection strategies. Our results have shown the screening and identification of two oligonucleotide sequences (substrates) as the most promising probes for detecting Salmonella – Sal-3 and Sal-5. The detection limits for both probes were determined with the reference Salmonella Typhimurium (STM 1) and Salmonella Enteritidis (SE 1) cultures. Sal-3 has reported LOD values around 105 CFU mL-1 for STM 1 and 104 CFU mL-1 for SE 1, while Sal-5 proves to be a slightly better probe, with LODs of 104 CFU mL-1 for STM 1 and 104 CFU mL-1 for SE 1. Both selected probes have shown the capability to recognize 49 out of 51 different Salmonella serotypes tested in vitro and the most frequent serotypes in porcine mesenteric lymph nodes as a standard sample used in fattening-pig salmonellosis baseline studies. Notably, our results showed 100% correlation between nuclease detection and the PCR-InvA or ISO-6579 standard method, underlining the great potential of this innovative nucleic acids technology to be implemented as a rapid method for food safety testing.Graphical abstractImage 1
  • A Mitochondria-targeted and FRET-based ratiometric fluorescent probe for
           detection of SO2 derivatives in water
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Dongsheng Zhang, Aikun Liu, Ruixue Ji, Jian Dong, Yanqing Ge A mitochondria-targeted ratiometric fluorescent probe based on the fluorophore pyrido[1,2-a]benzimidazole was developed. It showed high sensitivity and selectivity toward SO2 derivatives in water. The probe was also successfully applied to detect intrinsically generated SO2 derivatives in living glioma cells, which may be helpful in ascertaining the biological roles of SO2 in mitochondria.Graphical abstractImage 1
  • Ionic liquid modified molybdenum disulfide and reduced graphene oxide
           magnetic nanocomposite for the magnetic separation of dye from aqueous
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Rui Ni, Yuzhi Wang, Xiaoxiao Wei, Jing Chen, Panli Xu, Wei Xu, Jiaojiao Meng, Yigang Zhou A novel ionic liquid (IL) modified magnetic nanocomposite (mag-MoS2-RGO), which was composed of molybdenum disulfide (MoS2) and reduced graphene oxide (RGO), was firstly synthesized and characterized (mag-MoS2-RGO-IL). Compared with mag-MoS2-RGO, the mag-MoS2-RGO-IL exhibited the higher adsorption capacity of 143.9 mg/g for methylene blue (MB) under optimum conditions. Experimental results were imitated by adsorption isotherms and kinetic models, revealing a monolayer adsorption on the homogeneous surface governed by chemisorption. The removal rate was maintained 78% after 5 cycles of regeneration, indicating its good reutilization. Methodological study suggested that the method possessed excellent repeatability, precision and stability. The recoveries from the real samples were in the range of 87.0-98.8% with relative standard deviation of ≤ 5.2%. Benefiting from composite structure and magnetic Fe3O4, the stable magnetic adsorbent can be quickly separated from aqueous solution. All of above proves that the prepared mag-MoS2-RGO-IL has great application potential in dye separation.Graphical abstractImage 1
  • PtNi bimetallic nanoparticles loaded MoS2 nanosheets: preparation and
           electrochemical sensing application for the detection of dopamine and uric
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Lian Ma, Qiaran Zhang, Chao Wu, Yue Zhang, Lintao Zeng Composite nanomaterials are particularly useful and offer many excellent opportunities for electrochemical sensing application. Depending on the high catalytic activity of bimetallic nanoparticles, the large specific surface area, abundant active edges and co-catalytic function of MoS2 nanosheets, we, for the first time, prepared a novel PtNi bimetallic nanoparticles loaded MoS2 nanosheets (PtNi@MoS2) hybrid material by a co-reduction method for the electrochemical sensing application. The nanocomposite is characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), and then casted on a bare glassy carbon electrode (GCE) to fabricate an electrochemical sensor (PtNi@MoS2/GCE). The electrochemical investigation showed that the sensor performed good selectivity and wide linear ranges for the simultaneous detection of dopamine (0.5−150 μM) and uric acid (0.5−600 μM). And the detection limits were down to 0.1 μM (S/N = 3) for both analytes.Graphical abstractFor the first time, a nanocomposite of PtNi bimetallic naoparticles loaded MoS2 nansheets was prepared by a co-reduction method and was used to establish an electrochemical sensor for the simultaneous detection of dopamine and uric acid. The sensor showed excellent performance and had been successfully applied for the simultaneous determination of the two analytes in human urine samples.Image 1
  • Label-free fluorescent discrimination and detection of epinephrine and
           dopamine based on bioinspired in situ copolymers and excitation wavelength
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Ying Zhang, Wang Ren, Yu Zhu Fan, Jiang Xue Dong, Hui Zhang, Hong Qun Luo, Nian Bing Li A simple and label-free fluorescence turn-on method is proposed for the discrimination and detection of epinephrine (Ep) and dopamine (DA) via polyethyleneimine (PEI)-initiated in situ copolymerization and excitation wavelength switch. The PEI solution in the presence of Ep, DA and the mixture of Ep and DA are denoted as PEp-PEI, PDA-PEI and MEp-DA, respectively. In this study, PEI aqueous solution medium initiates the auto-oxidization of Ep and DA and the bioinspired copolymerization. These resultant copolymers emit yellow-green fluorescence color with a fluorescence emission maximum at 515 nm. Interestingly, these fluorescent copolymers exhibit distinct different excitation spectra, although Ep and DA are structurally very similar. PDA-PEI exhibits only one excitation peak at 385 nm, and PEp-PEI shows dual-excitation mode with two significant excitation peaks at 328 nm and 405 nm, respectively. MEp+DA also shows dual-excitation mode with two excitation peaks at 330 nm and 395 nm, respectively. Thus, individual Ep, DA, and their mixture can be discriminated based on the different excitation spectral shapes and peak locations of PEp-PEI, PDA-PEI and MEp+DA. Furthermore, the quantitative analysis of Ep and DA in mixture can also be achieved by switching excitation wavelength between 330 and 395 nm and monitoring the fluorescence emission intensity of MEp+DA at 515 nm. The fluorescence intensity of MEp+DA only related to the concentration of Ep when excited at 330 nm. Moreover, the concentration of DA can also be calculated by subtracting the fluorescence intensity of PEp-PEI from the total fluorescence intensity when excited at 395 nm. The resultant method has been used to simultaneously detect Ep and DA in human urine samples. The proposed fluorescence system is facile, eco-friendly, low-cost, and time-saving, and also provides a new and simple path for discriminating analogues.Graphical abstractImage 1
  • Unlocking the Hidden Talent of DNA: Unexpected Catalytic Activity for
           Colorimetric Assay of Alkaline Phosphatase
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Qingwei Huang, Chuan He, Jinli Zhang, Wei Li, Yan Fu Carboxylic acids have been efficiently used to activate H2O2 to form even more potent oxidant-peroxy acids through enzyme-catalyzed processes. By employing acetic acid as the activator, herein we report for the first time that cofactor-free DNA displays unexpected activity in H2O2-mediated oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) under mild conditions. A series of 10-nt oligonucleotides were rationally designed with various combinations of double nucleotides including TG, AG, CG, TA and AC respectively, which demonstrates that the catalytic performance of DNA is highly dependent upon the sequence composition, strand length and continuous nucleotides. Inspired by phosphate-induced inhibition effects on the formation of peracetic acid, an ultrasensitive assay was well-established for monitoring alkaline phosphatase (ALP) on the basis of double terminal-phosphorylated G-rich oligonucleotides. Phosphorylated DNA not only serves as the substrate for ALP-catalyzed hydrolysis, but also acts as the enzyme-like catalyst for signal amplification. Quantitative determination of ALP is realized in a linear range from 0.05 to 15 mU/mL, resulting in the limit of detection of 0.01 mU/mL. The rapid and reliable test also has great potential in analyzing serum samples for practical disease diagnosis.Graphical abstractImage 1
  • Thermophoretic diagnosis of autoimmune diseases based on Escherichia coli
           with autodisplayed autoantigens
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Ga-Yeon Lee, Ji-Hong Bong, Gu Yoo, Ji Yun Kim, Min Park, Min-Jung Kang, Joachim Jose, Jae-Chul Pyun The autoimmune diseases systemic lupus erythematosus (SLE) and Sjogren’s syndrome (SS) are diagnosed by detection of autoantibodies against Ro and La protein autoantigens, respectively. In this work, the diagnosis of autoimmune diseases SLE and SS was demonstrated using thermophoresis of Escherichia coli with the autodisplayed autoantigens. Ro and La protein autoantigens were autodisplayed by constitutive expression together with a fluorescent protein called tdTomato in the cytosol. The binding affinity of the autodisplayed autoantigens was tested against positive and control sera by using FACS as a reference method. The factors influencing interactions between E. coli with autodisplayed autoantigens and autoantibodies in sera during thermophoresis were analyzed by measurement of cell surface charge and size before and after interaction. Finally, the thermophoretic diagnosis of autoimmune diseases SLE and SS was demonstrated using sera from patients afflicted with the respective diseases by estimating sensitivity and selectivity from ROC plots.Graphical abstractImage 1
  • Determination of residual organophosphorus thioester pesticides in
           agricultural products by chemical isotope-labelling liquid
           chromatography-tandem mass spectrometry coupled with in-syringe dispersive
           solid phase clean-up and in situ cleavage
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Yanxin Yu, Jinmao You, Zhiwei Sun, Guoliang Li, Zhongyin Ji, Shijuan Zhang, Xuxia Zhou Chemical isotope labelling in combination with high-performance liquid chromatography-tandem mass spectrometry (CIL-HPLC-MS/MS) is a powerful method for quantitative profiling of targeted molecules. In the current work, we successfully developed a novel CIL-HPLC-MS/MS method for quantitative profiling of residual organophosphorus thioester pesticides (OPTPs) in agricultural products through the determination of the cleavage products of thiol (CP-thiol) compounds. In this method, we synthesized a novel pair of CIL reagents, i.e., N-(4-(carbazole-9-yl)-phenyl)-N-maleimide (NCPM-d0) and its deuterated analogue NCPM-d2, both of which contain a maleimide moiety as the reactive group and an isotope tag to sensitively label CP-thiol compounds. NCPM-d0 was used to label CP-thiol compounds cleaved from OPTPs in the investigated agricultural product samples, and NCPM-d2 was used to label CP-thiol compounds cleaved from OPTPs in the standard substance-spiked organic agricultural product samples. The heavily labelled derivatives were used as the internal standards (ISs) to compensate for the matrix effects during MS analysis. The NCPM-d0- and NCPM-d2-labelled derivatives generated two characteristic product ions (PIs) at m/z 372.5 and 374.5 under collision induced dissociation, respectively, which are used to establish the multiple reaction monitoring (MRM) mode-based detection. The precursor ions of NCPM-d0 and NCPM-d2 labelled derivatives of CP-thiol compounds were deduced according to the structures of the OPTPs. The peak pairs with a fixed mass difference and similar retention times were assigned as potential CP-thiol candidates for the identification of the corresponding OPTPs. Using the proposed method, we successfully determined seven residual OPTPs in agricultural product samples. Taken together, the presented method was demonstrated to be a promising new technique in the quantitation of OPTPs in agricultural product samples with high reliability.Graphical abstractImage 1
  • A reusable electrochemical sensor for one-step biosensing in complex media
           using triplex-forming oligonucleotide coupled DNA nanostructure
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Yucai Yang, Yue Huang, Chao Li Here we report an electrochemical DNA (E-DNA) sensor to detect a variety of analytes by using a novel interfacial probe that rationally integrates triplex-forming oligonucleotide (TFO) into a tetrahedral DNA nanostructure (TDN). In the presence of analyte, the blocked TFO is released and subsequently binds the edge of TDN to form a triplex DNA structure, which confines the redox reporter to be in close proximity to the underlying electrode and enhances the electrochemical signal. Thanks to the unique design and property of the probe, the proposed sensor could efficiently suppress the background signal (from 0.69 μA to 0.092 μA) and thus enhance the signal-to-noise ratio, resulting in improved sensing performance. Furthermore, the sensor displays new merits such as rapid response (∼35 min), one-step operation, easy regeneration (buffer change) and good generality (changing recognition element) compared with traditional TDN-based E-DNA sensor using enzyme displays signal transducer. In addition, to demonstrate real-world applicability of this new sensor, we have successfully detected different analytes (e.g., DNA, protein, and metal ion) in the complex media (e.g., serum, blood, and lake water), implying its considerable potential for precise bioanalysis in the future.Graphical abstractAn electrochemical DNA (E-DNA) sensor to detect a variety of analytes by using a novel interfacial probe that rationally integrates triplex-forming oligonucleotide (TFO) into a tetrahedral DNA nanostructure (TDN) was developed.Image 1
  • A self-digitization chip integrated with hydration layer for low-cost and
           robust digital PCR
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Yongfeng Ning, Xu Cui, Chao Yang, Fengxiang Jing, Xiaojun Bian, Lin Yi, Gang Li We present a self-discretization and zero-water-loss microfluidic digital PCR (dPCR) device to enable low-cost and robust quantitative nucleic acid assays. In this device, a thin void is integrated beneath the reaction chamber array. By utilizing the permeability of polydimethylsiloxane (PDMS) film, the integrated void serves a dual function: vacuum “accumulator” and hydration “reservoir”. The combination of pre-stored pumping energy and water compensation for evaporation loss enables simple, robust and reliable single-DNA-molecule amplification and detection in 10,000 reactors of picoliter volume. Compared to the conventional degassing PDMS pumps, the vacuum accumulator exhibits superior performance due to more vacuum storage and shorter diffusion distance. We also evaluated the performance of the embedded hydration layer in suppressing evaporation loss at elevated temperatures, and verified that zero-water-loss could be achieved for all reaction chambers in our dPCR chip during thermal cycling. By performing quantitative detection of T790M DNA from 10 to 104 copies/μL, the proposed dPCR chip demonstrated high accuracy and excellent performance for the absolute quantification of the target gene with a dynamic range of 104. The simplicity and robustness of our dPCR chip make it well suited for low-cost molecular diagnostic assays under resource-limited settings.Graphical abstractImage 1
  • Mass Spectrometric Imaging Reveals Photocatalytic Degradation
           Intermediates of Aromatic Organochlorines Resulting from Interfacial
           Photoelectron Transfer and Hydroxyl Radical Abstraction on Semiconductor
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Xuemei Tang, Yinghua Qi, Wenyang Zhang, Juan Zhang, Ruowei Jiang, Hongying Zhong Organochlorines are highly persistent and toxic contaminants that are widely distributed and accumulated in various aquatic or soil environments as well as food chains. Heterogeneous photocatalytic degradation of such pollutants by using semiconductor nanoparticles has been recognized as one of the effective purification ways. Understanding of degradation mechanisms and designing of highly efficient semiconductor nanoparticles require structural identification of various degradation intermediates that are difficult to achieve with current spectroscopic techniques. Herein a mass spectrometric approach was developed to tackle interfacial photoelectron transfer and hydroxyl radical abstraction on different semiconductor nanoparticles. Chlorobenzenes (including hexachlorobenzene and chlorothalonil) adsorbed on the surfaces of nanoparticles were found to instantly undergo dechlorination and ring dissociation through photoelectron capture dissociation and abstraction of a chlorine atom from aromatic C-Cl bond by hydroxyl radicals. Different intermediates have been unambiguously identified with experimental evidences provided by a Q-TOF mass spectrometer. It has been demonstrated that both electron density around atoms and steric effects of side chains contribute to the site selectivity for photoelectron capture and hydroxyl radical abstraction. But the energies needed for chemical bond cleavages and the stabilization of acquired charges play important roles in degradation efficiency. By using mass spectrometric imaging, photocatalytic differences of different semiconductor nanoparticles have been revealed.Graphical abstractImage 1
  • Magnetic γ-cyclodextrin polymer with compatible cavity promote the
           magnetic solid-phase extraction of microcystins in water samples
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Chuanhui Huang, Yujie Wang, Qiao Huang, Yu He, Lan ZhangABSTRACTMicrocystins (MCs), which are produced by eruptive cyanobacteria, seriously threaten the health of humans for their poisonousness. Herein, a facile strategy was introduced to synthesize the magnetic γ-cyclodextrin polymer (Fe3O4@PDA@γ-CDP) composite and set it as a novel adsorbent with excellent properties for the magnetic solid-phase extraction (MSPE) of MCs. The prepared Fe3O4@PDA@γ-CDP micropheres exhibit good aqueous dispersibility and highly affinity for MCs, thus contribute to an excellent extraction performance for trace MCs in water samples. Combined with HPLC–MS/MS, a handy, sensitive and efficient method was developed for detection of MCs in water samples, which shows good linearity (R2 ≥ 0.9992) in the range of 1.0–1000 pg mL-1, low limits of detection (0.8–2.0 pg mL-1, S/N = 3), satisfactory repeatability with the relative standard deviations (RSDs) lower than 6.2% (n = 5). At last, the proposed method was successfully applied for the extraction and detection of MCs in fresh water and sea water samples, which provides great potential of trace-level MCs determination in lake and sea water.Graphical abstractImage 1
  • Highly Efficient Polyaniline-MoS2 Hybrid Nanostructures Based Biosensor
           for Cancer Biomarker Detection
    • Abstract: Publication date: Available online 21 December 2018Source: Analytica Chimica ActaAuthor(s): Amrita Soni, Chandra Mouli Pandey, Manoj Kumar Pandey, Gajjala Sumana In this work, polyaniline nanospindles have been synthesized using iron oxide as sacrificial template. These nanospindles were utilized for the fabrication of PANI-MoS2 nanoflower architectures via hydrothermal route. The electrostatic interaction between PANI and MoS2 improves the conductivity and provide more direct paths for charge transportation. SEM, TEM, XRD, Raman Spectroscopy techniques were employed to explore the crystal structure, and morphological properties of the PANI-MoS2 nanocomposite. Furthermore, an electrochemical biosensing platform based on PANI-MoS2 nanocomposite was fabricated for the specific detection of chronic myelogenous leukemia (CML) by using electrochemical impedance spectroscopy technique. The binding interactions between the pDNA/PANI-MoS2/ITO bioelectrode and target DNA sequence were also studied. The biosensor exhibits high sensitivity and wide detection range (10-6 M to 10-17 M) of target DNA with low detection limit (3×10-18 M). Additionally, the specificity studies of the genosensor with various target DNA sequences (complementary, noncomplementary and one base mismatch) and real samples analysis of CML shows its potential for clinical diagnostics.Graphical abstractImage 1
  • Mustard seeds derived fluorescent carbon quantum dots and their
           peroxidase-like activity for colorimetric detection of H2O2 and ascorbic
           acid in a real sample
    • Abstract: Publication date: Available online 20 December 2018Source: Analytica Chimica ActaAuthor(s): Subhash Chandra, Vikas Kumar Singh, Pradeep Kumar Yadav, Daraksha Bano, Vijay Kumar, Vinay Kumar Pandey, Mahe Talat, Syed Hadi Hasan Herein, we were synthesized fluorescent carbon quantum dots via facile one-step hydrothermal treatment of mustard seeds (M-CQDs). It showed excellent optical property with fluorescent quantum yield 4.6 %. The as-prepared M-CQDs exhibited peroxidase-like mimetic activity and catalyzed the oxidation of chromogenic substrate 3,3’,5,5’-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue color reaction mixture with the prominent peak at 652 nm. Furthermore, the peroxidase-like activity performance of M-CQDs followed the steady-state kinetics behavior and exhibited similar catalytic activity as that of natural enzyme Horseradish peroxidase (HRP). In addition to this, the double reciprocal plot showed a parallel line which suggested the occurrence of Ping-Pong type of mechanism. The H2O2 dependent oxidation of TMB was helpful for the colorimetric detection of H2O2 in the linear range of 0.02 to 0.20 mM with the limit of detection (LOD) of 0.015 mM. Interestingly, the oxidized TMB was further reduced to native TMB by the reducing agent ascorbic acid. Hence M-CQDs showed its potential towards the selective and sensitive detection of ascorbic acid in the linear range of 10 to 70 μM having a correlation coefficient of 0.998 with LOD of 3.26 μM. The practical feasibility of the proposed detection method of AA was also investigated in common fresh fruits.Graphical abstractImage 1
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Heriot-Watt University
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