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Publisher: Elsevier   (Total: 3162 journals)

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Showing 1 - 200 of 3162 Journals sorted alphabetically
A Practical Logic of Cognitive Systems     Full-text available via subscription   (Followers: 9)
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 30, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 22, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 90, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 25, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 34, 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: 404, 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: 8, 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: 241, 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: 10, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 1, SJR: 1.793, CiteScore: 6)
Acta Poética     Open Access   (Followers: 4, SJR: 0.101, CiteScore: 0)
Acta Psychologica     Hybrid Journal   (Followers: 27, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 6, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 6)
Acute Pain     Full-text available via subscription   (Followers: 15, SJR: 2.671, CiteScore: 5)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.53, CiteScore: 4)
Addictive Behaviors     Hybrid Journal   (Followers: 16, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 8, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 9, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Advanced Cement Based Materials     Full-text available via subscription   (Followers: 3, SJR: 0.732, CiteScore: 3)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 140, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 16, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 8, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 12, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 28, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 10, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 10, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 22, 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: 30, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 7, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 3)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 27, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.713, CiteScore: 1)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 10, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 28, 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: 11)
Advances in Digestive Medicine     Open Access   (Followers: 8)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 24)
Advances in Ecological Research     Full-text available via subscription   (Followers: 43, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 27, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 44, SJR: 5.39, CiteScore: 8)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 54, 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: 15, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 8, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 21)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 36, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Marine Biology     Full-text available via subscription   (Followers: 14, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 11, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 21)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 3)
Advances in Oncobiology     Full-text available via subscription   (Followers: 1)
Advances in Organ Biology     Full-text available via subscription   (Followers: 1)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 16, 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: 10)
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: 8)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 6)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 62)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (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: 5)
Advances in Space Research     Full-text available via subscription   (Followers: 392, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
Advances in Surgery     Full-text available via subscription   (Followers: 10, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 31, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 17)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 46, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 335, 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: 442, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 16, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 32, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 44, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 1)
Agriculture and Natural Resources     Open Access   (Followers: 2)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 57, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 6, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 11, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 9)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 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: 9, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 50, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 4, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 4, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 6)
American Heart J.     Hybrid Journal   (Followers: 50, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 54, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 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: 32, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 26, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 34, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 43)
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: 201, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 61, 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: 27, 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: 37, 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: 6)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 62, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 16, 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: 40, SJR: 1.512, CiteScore: 5)
Analytical Biochemistry     Hybrid Journal   (Followers: 169, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 10, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 11)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 23, SJR: 0.683, CiteScore: 2)
Angiología     Full-text available via subscription   (SJR: 0.121, CiteScore: 0)
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1, SJR: 0.111, CiteScore: 0)

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Journal Cover
Analytica Chimica Acta
Journal Prestige (SJR): 1.512
Citation Impact (citeScore): 5
Number of Followers: 40  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0003-2670 - ISSN (Online) 1873-4324
Published by Elsevier Homepage  [3162 journals]
  • Corrigendum to “Advances in sensing and biosensing of bisphenols: A
           review” [ACA 998 (2018) 1–27]
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Dhanjai, Ankita Sinha, Lingxia Wu, Xianbo Lu, Jiping Chen, Rajeev Jain
       
  • Centrifugal partition chromatography a first dimension for biomass fast
           pyrolysis oil analysis
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Agnès Le Masle, Sandra Santin, Léa Marlot, Ludovic Chahen, Nadège Charon Biomass fast pyrolysis oils contain molecules having a large variety of chemical functions and a wide range of molecular weights (from several tens to several thousand grams per mole). The good knowledge of their complex composition is essential for optimizing the conversion of bio-oils to biofuels, thereby requiring powerful separation techniques. In this work, we investigate the interest of centrifugal partition chromatography (CPC) as a first dimension for the analysis of a bio-oil. A CPC method is proposed to separate oxygen containing compounds according to their partition coefficients in the solvent system. This approach is a powerful and easy-to-use technique that enables fractionation of a bio-oil at a semi-preparative scale, without any sample loss related to adsorption on the stationary phase. Collected fractions are then injected in liquid chromatography as a second dimension of separation. Contour plot representations of the CPC × LC separation are established to discuss the potential of this approach. These representations can be used as a veritable fingerprint in the comparison of different samples or samples at different steps of a conversion process but also as a powerful tool to identify new compounds and describe the entire composition of the bio-oil.Graphical abstractImage 1
       
  • Readily prepared iminocoumarin for rapid, colorimetric and ratiometric
           fluorescent detection of phosgene
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Weiyong Feng, Shengyi Gong, Enbo Zhou, Xinyu Yin, Guoqiang Feng In this paper, a new colorimetric and ratiometric fluorescent probe for the rapid detection of phosgene is reported. This probe is based on a readily prepared and highly fluorescent iminocoumarin, which reacts rapidly with phosgene to form a cyclic carbamate product to produce, distinctive colorimetric and ratiometric fluorescent signal changes. The detection of phosgene with this probe is fast (complete within 2 min), highly selective and sensitive with a detection limit of 27 nM in solution. Moreover, this probe can be used to prepare easy-to-use paper test strips for convenient visual and fluorescent detection of phosgene gas even at a concentration of 0.1 mg/L. Overall, this work provides a very promising dual colorimetric and ratiometric fluorescent probe for rapid and sensitive detection of phosgene both in solution and in the gas phase.Graphical abstractImage 1
       
  • Surface enhanced Raman spectroscopy based immunosensor for ultrasensitive
           and selective detection of wild type p53 and mutant p53R175H
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Anna Rita Bizzarri, Ilaria Moscetti, Salvatore Cannistraro p53 is a powerful transcription factor playing a pivotal role in the prevention of cancer development and in maintaining genome integrity. This oncosuppressor is found to be functionally inactivated by mutations in many human tumors. Accordingly, wild type p53 and its oncogenic mutants represent valuable cancer biomarkers for diagnostic and prognostic purposes. We developed a highly sensitive biosensor, based on Surface Enhanced Raman Spectroscopy, for detection of wild type p53 and of p53R175H, which is one of the most frequent tumor-associated mutants of p53. Our approach combines the huge Raman signal enhancement, mainly arising from the plasmonic resonance effect on molecules close to gold nanoparticles, with the antigen-antibody biorecognition specificity. By following the enhanced signal of a specific Raman marker, intrinsic to the nanoparticle-antibody bioconjugation, we were able to push the antigen detection level down to the attomolar range in buffer and to the femtomolar range in spiked human serum. The method demonstrated a high reproducibility and a remarkable selectivity in discriminating between wild type p53 and p53R175H mutant, in both buffer and serum. A calibration plot was built and validated by ELISA for a reliable quantification of p53. These findings entitle our SERS-based immunosensor as a powerful and reliable tool for a non-invasive screening in human serum targeting p53 network. The approach could be easily extended to ultrasensitive detection of other markers of general interest, with feasible implementations into multiplex assays, functioning as lab-on-chip devices for several applications.Graphical abstractImage 1
       
  • New colorimetric aptasensor for rapid on-site detection of Campylobacter
           jejuni and Campylobacter coli in chicken carcass samples
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Young-Ji Kim, Hong-Seok Kim, Jung-Whan Chon, Dong-Hyeon Kim, Ji-Yeon Hyeon, Kun-Ho Seo Campylobacter is the most common cause of infectious intestinal disease, with nearly all cases caused by two species: C. jejuni and C. coli. We recently reported a gold nanoparticle-based two-stage aptasensing platform, which was improved in the present study for the rapid and on-site detection of both C. jejuni and C. coli in food samples. Compared to the previous platform, the improved platform yielded a more obvious colour change from red to purple due to the aggregation of gold nanoparticles, and does not require additional time or a pH optimization step for the aptamers to be adsorbed onto the gold nanoparticles. Using a highly specific aptamer that binds to live C. jejuni and C. coli, the improved aptasensor was highly effective for testing pure culture samples. The accuracy of the newly developed platform was comparable (p = 0.688) to that of the gold-standard detection method of tazobactam-supplemented culture, whereas it was superior to the official agar-based detection method (p = 0.016) in a validation study with 50 naturally contaminated chicken carcass samples. This is the first study on a colorimetric sensor that targets both live C. coli and C. jejuni in naturally contaminated samples. In addition, we provide the first evidence that both morphological status and the amount of Campylobacter present play key roles in the effectiveness of colorimetric detection. Thus, suitable selection of an antibody or aptamer with consideration of the morphological status of pathogens in samples is essential for direct detection without enrichment. Our data suggest that the sensor developed in this study can provide an excellent screening method, with a reduction in the detection time from 48 h to 30 min after enrichment, thus saving time, labour, and cost.Graphical abstractImage 1
       
  • A homogeneous, Anti-dsDNA antibody-based assay for multicolor detection of
           cancer stem cell transcription factors
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Jiehua Ma, Hai Shi, Meiling Zhang, Chao Li, Yang Xiang, Ping Liu Cancer stem cells (CSCs) are responsible for maintaining tumor growth, metastasis and recurrence. The high expression of cancer stem cell transcription factors (Oct4, Sox2 and Nanog) is a valuable prognostic factor, suggesting a higher risk of tumor recurrence and metastasis. So, the development of a convenient and cost-effective method for multiplex assay of these transcription factors (TFs) is highly required. In this work, we have proposed a universal homogeneous assay for multicolor detection of these TFs based on anti-dsDNA antibody-decorated Fe3O4 magnetite nanoparticles (aadMNPs). In the presence of analytes, the dye-labeled dsDNAs are bound by specific TFs, which will inhibit the interactions between the dsDNAs and aadMNPs, generating higher fluorescence that may provide signal readout for the immunosensing process. By using the proposed method, Oct4 can be determined in a linear range from 3 to 1200 ng/mL with a detection limit of 0.035 ng/mL. Furthermore, we have presented assays for the sensitive, selective and rapid detection of Oct4, Sox2 and Nanog in cell extract, as well as the analysis of binding affinity of the mutated binding sequences. This work may provide potential applications in clinical CSCs detections, and may open new opportunity for the study of nucleotide polymorphisms in TF binding sites.Graphical abstractImage 1
       
  • Nanobody-based dual epitopes protein identification (DepID) assay for
           measuring soluble CD38 in plasma of multiple myeloma patients
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Ting Li, Song Lu Li, Cheng Fang, Yun Nan Hou, Qiaoxia Zhang, Xin Du, Hon Cheung Lee, Yong Juan Zhao BackgroundCD38 is a surface membrane antigen highly expressed in malignant blood cells, such as multiple myeloma (MM). A soluble form of CD38 (sCD38) is also present in the plasma, deriving likely from the shedding from the cells. The plasma levels of sCD38 should thus correlate closely with the proliferation of the MM cells, allowing the development of a simple diagnostic blood test for monitoring the progress of the disease. However, the plasma sCD38 levels are extremely low, requiring the design of a highly sensitive and specific assay.ResultsIn this study, we developed an ultra-sensitive assay, based on two nanobodies (Nbs) targeting two distinct epitopes of sCD38. One Nb acts as a capturer, and the other is fused with the firefly luciferase serving as a reporter to ensure sensitivity. We showed that this Dual epitopes protein IDentification (DepID) assay has sensitivity reaching 10 pg/mL, which is 10 times higher than that of a commercial ELISA kit. By this method, we were able to precisely quantify the levels of sCD38 in the plasma of MM patients, which were significantly higher than those from healthy donors. We further showed that the increase plasma levels of sCD38 correlated with the progress of MM.ConclusionWe have developed a Nb-based luminescence sandwich assay, named as DepID, for quantification of the soluble CD38 in MM patients' plasma and showed the potency of this method as a tool for general diagnosis of MM or companion diagnosis of the CD38-targeted therapies.Graphical abstractImage 1
       
  • Bifunctional aptamer-mediated catalytic hairpin assembly for the sensitive
           and homogenous detection of rare cancer cells
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Jumei Liu, Ye Zhang, Qianwen Zhao, Bo Situ, Jiamin Zhao, Shihua Luo, Bo Li, Xiaohui Yan, Pankaj Vadgama, Lei Su, Wen Ma, Wen Wang, Lei Zheng The presence of cancer cells in body fluids confirms the occurrence of metastasis and guides treatment. A simple, fast, and homogeneous fluorescent method was developed to detect cancer cells based on catalytic hairpin assembly (CHA) and bifunctional aptamers. The bifunctional aptamer had a recognition domain for binding to target cancer cells and an initiator domain for triggering the CHA reaction. In the presence of target cells, the bifunctional aptamer was released from the inhibitor and initiated a cascade reaction of assembly and disassembly of the hairpins. Separation of the fluorophores from the quenchers produced fluorescence signals. The proposed strategy showed high specificity for discriminating normal cells and leukocytes, and the detection limit was 10 cells/mL, which was lower than that of previous aptasensors. This assay was further tested using four kinds of clinical samples spiked with target cells to confirm its applicability. We developed a simple, rapid, and cost-effective method for the detection of cancer cells that did not require purification, and the approach holds great potential for bioanalysis and early diagnosis.Graphical abstractImage 1
       
  • Comprehensive evaluation of untargeted metabolomics data processing
           software in feature detection, quantification and discriminating marker
           selection
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Zhucui Li, Yan Lu, Yufeng Guo, Haijie Cao, Qinhong Wang, Wenqing Shui Data analysis represents a key challenge for untargeted metabolomics studies and it commonly requires extensive processing of more than thousands of metabolite peaks included in raw high-resolution MS data. Although a number of software packages have been developed to facilitate untargeted data processing, they have not been comprehensively scrutinized in the capability of feature detection, quantification and marker selection using a well-defined benchmark sample set. In this study, we acquired a benchmark dataset from standard mixtures consisting of 1100 compounds with specified concentration ratios including 130 compounds with significant variation of concentrations. Five software evaluated here (MS-Dial, MZmine 2, XCMS, MarkerView, and Compound Discoverer) showed similar performance in detection of true features derived from compounds in the mixtures. However, significant differences between untargeted metabolomics software were observed in relative quantification of true features in the benchmark dataset. MZmine 2 outperformed the other software in terms of quantification accuracy and it reported the most true discriminating markers together with the fewest false markers. Furthermore, we assessed selection of discriminating markers by different software using both the benchmark dataset and a real-case metabolomics dataset to propose combined usage of two software for increasing confidence of biomarker identification. Our findings from comprehensive evaluation of untargeted metabolomics software would help guide future improvements of these widely used bioinformatics tools and enable users to properly interpret their metabolomics results.Graphical abstractImage 1
       
  • Normal-inverse bimodule operation Hadamard transform ion mobility
           spectrometry
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Yan Hong, Chaoqun Huang, Sheng Liu, Lei Xia, Chengyin Shen, Yannan Chu In order to suppress or eliminate the spurious peaks and improve signal-to-noise ratio (SNR) of Hadamard transform ion mobility spectrometry (HT-IMS), a normal-inverse bimodule operation Hadamard transform - ion mobility spectrometry (NIBOHT-IMS) technique was developed. In this novel technique, a normal and inverse pseudo random binary sequence (PRBS) was produced in sequential order by an ion gate controller and utilized to control the ion gate of IMS, and then the normal HT-IMS mobility spectrum and the inverse HT-IMS mobility spectrum were obtained. A NIBOHT-IMS mobility spectrum was gained by subtracting the inverse HT-IMS mobility spectrum from normal HT-IMS mobility spectrum. Experimental results demonstrate that the NIBOHT-IMS technique can significantly suppress or eliminate the spurious peaks, and enhance the SNR by measuring the reactant ions. Furthermore, the gas CHCl3 and CH2Br2 were measured for evaluating the capability of detecting real sample. The results show that the NIBOHT-IMS technique is able to eliminate the spurious peaks and improve the SNR notably not only for the detection of larger ion signals but also for the detection of small ion signals.Graphical abstractImage 1
       
  • Colorimetric ionophore-based coextraction titrimetry of potassium ions
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Kajorngai Thajee, Lu Wang, Kate Grudpan, Eric Bakker Potassium ion concentration can be successfully determined volumetrically by moving the titration from a homogeneous phase to a two phase solvent system. This is because potassium can be readily complexed in a selective and thermodynamically stable manner by ionophores such as valinomycin. Previous work demonstrated the successful titration of potassium by ion-exchange into an organic phase containing valinomycin, but the sample itself served as titrant, which is not sufficiently practical for routine applications. This problem is overcome here by a co-extraction based approach, with the sodium salt of the water soluble lipophilic anion tetraphenylborate as titrant. The extraction of potassium tetraphenylborate must be preferred over that of the hydrogen ion-tetraphenylborate pair, which is used to indicate the endpoint by the presence of a lipophilic indicator in the organic phase. This is controlled by the sample pH, which for the conditions chosen here is around 7 for optimal sharpness and accuracy of the endpoint. The approach is demonstrated in a colorimetric detection approach, by use of a tethered digital camera and subsequent automated analysis of the resulting image files. The potassium analysis in a variety of samples is successfully demonstrated, including blood serum.Graphical abstractImage 1
       
  • Low-cost Scholl-coupling microporous polymer as an efficient solid-phase
           microextraction coating for the detection of light aromatic compounds
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Xintong Xie, Junhui Wang, Juan Zheng, Junlong Huang, Chuyi Ni, Jie Cheng, Zhengping Hao, Gangfeng Ouyang A cost-effective microporous polymer was synthesized using cheap monomer and catalyst via one-step Scholl-coupling reaction, and its chemical, morphological characteristics and pore structure were investigated. The as-synthesized polymer with large surface area and narrow pore distribution (centered in 1.2 nm) was prepared as a fiber coating for solid-phase microextraction (SPME). Headspace SPME was used for the extraction of the light aromatic compounds, e.g. benzene, toluene, ethylbenzene, m-xylene, naphthalene and acenaphthene. The parameters influencing the extraction and desorption efficiencies, such as extraction temperature and time, salt concentration, desorption temperature and time were investigated and optimized. The results showed that the home-made fiber had superior extraction efficiencies compared with the commercial PDMS fiber. Under the optimized conditions, low detection limits (0.01–1.3 ng/L), wide linear ranges (from 50 to 20000 ng/L to 1–20000 ng/L), good repeatability (4.2–9.3%, n = 6) and reproducibility (0.30–11%, n = 3) were achieved. Moreover, the practical applicability of the coating and proposed method was evaluated by determining the target light aromatic compounds in environmental water samples with satisfied recoveries (83.2%–116%).Graphical abstractImage 1
       
  • A novel mode of DNA assembly at electrode and its application to protein
           quantification
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Shaohua Ding, Zhipeng Gu, Ruhong Yan, Yuguo Tang, Peng Miao Sensitive and specific detection of protein is of great significance for early diagnosis and prognosis of many diseases. However, great challenges remain unsolved including relative low sensitivity, high cost, long testing time, complicated instrument and laborious operation. To improve the performance of protein detection methods, development of fine reaction interface for recognition and signal amplification is of great importance. In this work, we construct a novel mode of DNA assembly at electrode interface based on a tripodal surface anchor and an electrochemical aptasensor for protein assay is developed. The orientation of the immobilized DNA is optimized, which promises the efficiency of protein recognition. In addition, hybridization chain reaction is employed for further signal amplification. Therefore, this detection method shows high sensitivity with excellent specificity. The strategy can be universally applicable by simply modifying the sequences of used DNA probes.Graphical abstractImage 1
       
  • Cost-effective synthesis of three-dimensional nitrogen-doped
           nanostructured carbons with hierarchical architectures from the biomass of
           sea-tangle for the amperometric determination of ascorbic acid
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Yashuang Hei, Xiqian Li, Xiao Zhou, Jingju Liu, Mehboob Hassan, Siyi Zhang, Yu Yang, Xiangjie Bo, Hsing-Lin Wang, Ming Zhou In this work, the three-dimensional nitrogen-doped nanostructured carbons with hierarchical architectures (3D-NNCsHAs) with high density of defective sites, high surface area and pluralities of pore size distributions was prepared through the pyrolysis of sea-tangle (Laminaria japonica), an inexpensive, eco-friendly and abundant precursor. Benefitting from their structural uniqueness, a selective and sensitive ascorbic acid (AA) sensor based on 3D-NNCsHAs was developed. Compared to the glassy carbon electrode (GCE) and the carbon nanotubes modified GCE (CNTs/GCE), the 3D-NNCsHAs modified GCE (3D-NNCsHAs/GCE) presents higher performance towards the electrocatalysis and detection of AA, such as lower detection limit (1 μM), wider linear range (10–4410 μM) and lower electrooxidation peak potential (−0.02 V vs. Ag/AgCl). In addition, 3D-NNCsHAs/GCE also exhibits high anti-interference and anti-fouling abilities for AA detection. Particularly, the fabricated 3D-NNCsHAs/GCE is able to determine AA in real samples and the results acquired are satisfactory. Therefore, the 3D-NNCsHAs can be considered as a kind of novel electrode nanomaterial for the fabrication of selective and sensitive AA sensor for the extensive practical applications ranging from food analysis, to pharmaceutical industry and clinical test.Graphical abstractImage 1
       
  • Interfacial potential barrier driven electrochemical detection of
           Cr6+
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Yan He, Minggang Zhao, Meiyan Yu, Yunpeng Zhuang, Frank Cheng, Shougang Chen 3D NiO/polyaniline p-p junction foam was prepared and applied for electrochemical detection of Cr6+. The electrochemical detection using interfacial potential barrier was illustrated and a mature theoretical model was built to demonstrate the mechanism. Electrochemical sensing signals of targets can be revealed by changing the height of potential barrier after specific adsorption. The extra high sensitivity (0.78 μA nM−1) and low detection limit (3.96 × 10−4 nM) of Cr6+ were achieved by applying the p-p junction interfacial potential barrier as driven factors. This work proposes a model to apply the potential barrier for electrochemical detection of metal ions, which can be further developed for a wide range of specific substance detection.Graphical abstractImage 1
       
  • A lab-on-a-tip approach to make electroanalysis user-friendly and
           de-centralized: Detection of copper ions in river water
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Stefano Cinti, Vincenzo Mazzaracchio, Gökçe Öztürk, Danila Moscone, Fabiana Arduini The development of portable and user-friendly sensing platforms is a hot topic in the field of analytical chemistry. Among others, electroanalytical approaches exhibit a high amenability for reaching this purpose, i.e. the commercial strips for diabetes care are an obvious success. However, providing fully-integrated and user-friendly methods is the leitmotiv. In this work we evaluate the use of a disposable pipette tip, opportunely configured, to realize the first example of lab-on-a-tip. The combination of a pipette tip, wire electrodes, and cotton wool filter, highlights the suitability of producing a novel one-shot electroanalytical platform that does not require expertise-required tasks. To demonstrate the feasibility of this novel method, copper (Cu2+) is detected in water samples by means of anodic stripping voltammetry. The quantification is performed directly into the tip that contains a cotton wool filter: the filter has the double function of purifying the matrices from gross impurities and releasing all the pre-loaded reagents necessary for the assay. After optimizing the experimental parameters, the lab-on-a-tip was capable of detecting Cu2+ linearly up to 300 μg/L with a detection limit of 6.3 μg/L. The effectiveness of the platform was confirmed by testing 50, 100, and 150 ppb Cu-spiked river water sample with recovery value comprised between 92 and 103%.Graphical abstractImage 1
       
  • Outside Front Cover
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s):
       
  • Study of a complex secondary metabolites with potent anti-radical activity
           by two dimensional TLC/HPLC coupled to electrospray ionization
           time-of-flight mass spectrometry and bioautography
    • Abstract: Publication date: 31 October 2018Source: Analytica Chimica Acta, Volume 1029Author(s): Krzysztof Kamil Wojtanowski, Tomasz Mroczek The high performance liquid chromatography (HPLC) coupled to electrospray ionization (ESI) octopole orthogonal acceleration time-of-flight (TOF) mass spectrometry (MS) was developed to separate secondary metabolites belonging to different groups of compounds with a wide range of polarity, i.e. phenolic acids, flavonoids, sesquiterpenes and others present in minute amounts, in a single run.Moreover, application of ESI-TOF-MS with a simple in source type of fragmentation and high mass accuracy measurements (around 2 ppm) in both positive and negative ionization modes with different and optimized fragmentor voltages, enabled the identification of each single compound based on proposed fragmentation patterns. In this way a total number of 14 compounds in methanolic and water-methanolic (1:1, v/v) extract from fruits of Eryngium amethystinum and 6 compounds in extract from fruits of E. planum have been identified for the first time.Additionally, two dimensional thin layer chromatography/high performance liquid chromatography/electrospray-ionization-time-of-flight mass spectrometry (TLC/HPLC/ESI-TOF-MS) system was developed for identification of compounds with the highest anti-radical activity revealed in TLC-DPPH bioauthographic test. This on-line procedure enables significant improvement in terms of efficiency and faster structural analysis of the potential antioxidant natural compounds directly in the plant extracts screened for bioactivity tests. This effect – directed analysis (EDA) method enables separation, identification and preliminary screening of plant extracts for anti-radical properties and can be easily adopted for other bioactivities.Graphical abstractImage 1
       
  • Covalent bonding of Schiff base network-1 as a stationary phase for
           capillary electrochromatography
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Nengsheng Ye, Xuan Wang, Qingye Liu, Xiaoyu Hu Covalent organic frameworks (COFs), featuring low densities, high surface areas, and good thermal and chemical stabilities, are gradually attracting interest in the field of analytical chemistry. A type of microporous polymer network material named Schiff base network-1 (SNW-1) was introduced into a capillary column through covalent bonding. The obtained SNW-1-coated capillary column was characterized by thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. Then, the SNW-1-coated capillary column was successfully utilized for the open-tubular capillary electrochromatography (OT-CEC) separation of sulfonamides, cephalosporins, amino acids and parabens. The fabricated capillary column showed good separation efficiency (Rs > 1.4), stability and reproducibility (relative standard deviation (RSD) 
       
  • Behavior of selenium hydride in heated quartz tube and dielectric barrier
           discharge atomizers
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Jan Kratzer, Stanislav Musil, Karel Marschner, Milan Svoboda, Tomáš Matoušek, Zoltán Mester, Ralph E. Sturgeon, Jiří Dědina Atomization of SeH2 in an externally heated multiple microflame quartz tube atomizer (MMQTA) as well as planar dielectric barrier discharge (DBD) atomizer was investigated using a variety of probes. Deposits of Se on inner surfaces of the atomizers were quantified and their distribution visualized by autoradiography with 75Se radiotracer. The gas phase fraction of Se transported beyond the confines of the atomizers was also determined. In the MMQTA, a 15% mass fraction of Se was deposited in a narrow zone at both colder ends of the optical arm (100–400 °C). By contrast, a 25-40% mass fraction of Se was deposited homogeneously along the entire length of the optical arm of the DBD, depending on detection technique employed. The fraction of Se transported outside the MMQTA approached 90%, whereas it was 50–70% in the DBD. The presence of H2 was essential for atomization of selenium hydride in both atomizers. The gaseous effluent arising from the hydride generator as well as the atomizers was investigated by direct analysis in real time (DART) coupled to an Orbitrap-mass spectrometer, enabling identification of major gas phase species of Se.Graphical abstractImage 1
       
  • Hydrophilic interaction chromatography coupled to tandem mass spectrometry
           as a method for simultaneous determination of guanidinoacetate and
           creatine
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Pavle Jovanov, Milan Vraneš, Marijana Sakač, Slobodan Gadžurić, Jovana Panić, Aleksandar Marić, Sergej Ostojić The biosynthesis of creatine (Cr) is closely related to the bioavailability of guanidinoacetate (GAA). The lack of one or the other may compromise their role in the energy transport and cell signaling. A reliable estimate of their levels in biological samples is imperative since they are important markers of many metabolic disorders. Therefore, a new LC-MS/MS method for simultaneous determination and quantification of GAA and Cr by multiple reaction monitoring (MRM) mode was developed based on the hydrophilic interaction chromatography (HILIC) and response surface methodology (RSM) for the optimization of chromatographic parameters. The optimized parameters ensured good separation of these similar, very polar molecules (chromatographic resolution > 1.5) without prior derivatization step in a short analysis run (6 min). The developed method was validated to ensure accurate (R, 75.1–101.6%), precise (RSD 
       
  • High-frequency, dielectric spectroscopy for the detection of
           electrophysiological/biophysical differences in different bacteria types
           and concentrations
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Mohammad Russel, Marios Sophocleous, Shan JiaJia, Weiping Xu, Lehui Xiao, Thomas Maskow, Mahbub Alam, Julius Georgiou This paper describes a novel technique to quantify and identify bacterial cultures of Bacillus Subtilis (2.10–1.30 × 109 CFU mL−1) and Escherichia Coli (1.60–1.00 × 109 CFU mL−1), in corn oil using dielectric spectroscopy at elevated frequencies of 0.0100–20.0 GHz. This technique is using the electrophysiological/biophysical differences (e.g. gram positive and gram negative) between various bacteria types, as a basis to distinguish between bacteria concentrations and bacteria types. A close-ended, coaxial probe of 20.0 mm long sample-holder was developed and used to calculate the dielectric constant from the measured S parameters of the bacterial cultures, using the Nicolson-Ross-Weir method. This technique shows a linear relationship (r2 ≥ 0.999) between the dielectric constant and the cell concentration, at 16.0 GHz. The sensitivity of the technique is 0.177 × 109 (CFU mL−1)−1 for B. Subtilis (with a size of 10.0 × 1.00 μm), 0.322 × 109 (CFU mL−1)−1 for E. Coli (with a size of 2.00 × 0.500 μm) and 0.913 × 109 (CFU mL−1) −1 for their 1:1 mixture, while the response time is 60.0s. The dependency of dielectric constant on the bacterial cell concentration at a given frequency can be potentially exploited for measuring bacterial concentrations and biophysical differences.Graphical abstractImage 1
       
  • Novel epoxy-silica nanoparticles to develop non-enzymatic colorimetric
           probe for analytical immuno/bioassays
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Chandra K. Dixit, Snehasis Bhakta, John Macharia, Jared Furtado, Steven L. Suib, James F. Rusling We have developed a novel method to develop epoxy silica nanoparticles (EfSiNP) in a single pot. High surface coverage of epoxy functional groups between 150 and 57000 molecules per particles (∼1013–1016 molecules/mL of 200 nm EfSiNPs) was achieved for different preparation conditions. We then created a red colored probe by conjugating Fuchsin dye to the epoxy functionalities of EfSINPs. Anti-mouse IgG was co-immobilized with Fuchsin and their ratios were optimized for achieving optimum ratios by testing those in functional assays. Dye to antibody ratios were in good negative correlation with a coefficient of −1.00 measured at a confidence level of over 99%. We employed the developed non-enzymatic colorimetric immunonanoprobe for detecting mouse IgG in a direct immunoassay format. We achieved a sensitivity of 427 pg/mL with the assay.Graphical abstractImage 1
       
  • The aptamer-thrombin-aptamer sandwich complex-bridged gold nanoparticle
           oligomers for high-precision profiling of thrombin by dark field
           microscopy
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Jingjing Li, Yunfei Jiao, Qingyun Liu, Zhengbo Chen We present a simple and efficient colorimetric assay strategy for ultrasensitive visual detection of human α-thrombin, which is essentially based on the formation of the DNA1-thrombin-DNA2 sandwich complex-bridged gold nanoparticle (Au NP) oligomers. Unlike the traditional colorimetric sensing strategies which induced the nanoparticle aggregates with uncontrolled aggregate size. In this work, the DNA1with rich G bases was firstly conjugated on the surfaces of Au NPs fixed on the hexadecyl trimethylammonium bromide (CTAB)-coated glass slide, and thrombin was captured by the DNA1. Then, the other DNA2 with rich G bases interacted with the former DNA1-thrombin complex and formed a DNA1-thrombin-DNA2 sandwich complex. The subsequently added Au NPs can be bound to the Au NP-DNA1-thrombin-DNA2 via Au-S bond to trigger the formation of Au NP oligomers, an apparent color change of the single Au NPs from green to yellow and red was observed under dark field microscopy. By measuring the intensity change of the yellow and red Au NPs, the concentration of target thrombin could be accurately quantified. As a proof of concept experiment, the formation of Au NP oligomers resulted in significantly improved sensitivity (10 fM of limit of detection and 20 fM of limit of quantity) and wider linear dynamic range of thrombin detection (20 fM-20 nM), the relative standard deviation (RSD) was less than 5.73% (n = 5). In addition, in order to validate the potential application in clinical diagnosis, the content of thrombin in a human serum samples was also quantified.Graphical abstractImage 1
       
  • Enzyme-linked immunosorbent assays for therapeutic drug monitoring
           coumarin oral anticoagulants in plasma
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): J.-Pablo Salvador, Dolors Tassies, Joan-Carles Reverter, M.-Pilar Marco The development of high-throughput immunochemical assays to assist on precision medicine for patients treated with coumarin oral anticoagulants (OA) is reported. The assays are able to quantitate Warfarin (W) and/or Acenocoumarol (ACL) directly in plasma samples without any previous sample pretreatment. The detectabilities (W, 3.52 ± 2.25 nM and ACL, 1.56 ± 0.64 nM) and the working ranges achieved (W, 1.19 ± 0.73 to 12.05 ± 2.99 nM and ACL 0.63 ± 0.20 to 10.19 ± 6.69 nM) are within the therapeutic levels usually found in patients treated with these drugs. The assays are specific with only cross-recognition of 4′-NH2-ACL on the ACL ELISA, which is one of the main metabolites of this drug. Moreover, accuracy studies performed with blind spiked samples show very good correlation between the spiked and the measured concentrations. Finally, a small clinical pilot study has been performed analyzing 96 plasma samples from treated and untreated patients, showing that the assay is able to quantitate ACL. The results obtained allow envisaging the possibility to use these assays for pharmacokinetic studies, dosage assessment or therapeutic drug monitoring.Graphical abstractImage 1
       
  • Use of MPA-capped CdS quantum dots for sensitive detection and
           quantification of Co2+ ions in aqueous solution
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Naim Bel Haj Mohamed, Nassim Ben Brahim, Randa Mrad, Mohamed Haouari, Rafik Ben Chaâbane, Michel Negrerie Water soluble CdS quantum dots (QDs) were synthesized by a simple aqueous chemical route using mercaptopropionic acid (MPA) as a stabilizer. These QDs had a fluorescence emission band maximum at 540 nm with a FWHM ∼130 nm and a quantum yield of ∼12%. Transmission electronic microscopy images were used to determine the QD diameter of 8.9 ± 0.4 nm. From this value we calculated the molecular mass M(QD) = 1.17 × 106 g mol−1 and the extinction coefficient at the band edge (450 nm) ε450 = 4.7 × 106 cm−1 M−1, which allowed to determine the true molar concentration of 17 nM for spectroscopic measurements in solution. The fluorescence intensity of MPA-CdS QDs was quenched only in the presence of Co2+ ions, but not in the presence of thirteen other metal cations. The fluorescence quenching of MPA-CdS QDs appeared proportional to the Co2+ concentration in the range 0.04–2 μM. Based on a fluorescence peak position and a lifetime both independent from Co2+ concentration, the quenching mechanism of MPA-CdS QDs appeared static. Because the strong electronic absorption of Co2+ overlaps the emission of QDs, our results can be explained by Förster energy transfer from QD to the bound Co2+ cations.Graphical abstractImage 1
       
  • A novel label-free fluorescent sensor for highly sensitive detection of
           bleomycin based on nitrogen-doped graphene quantum dots
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Xiaotong Liu, Weidan Na, Qing Liu, Xingguang Su In this work, we presented a novel label-free biosensor for rapid detection of bleomycinsulphate (BLM). The biosensor was based on the fluorescent “turn off-on” of nitrogen-doped graphene quantum dots (N-GQDs), which was prepared in a green way from citric acid and ammonia. The richness of carboxyl groups on the N-GQDs enabled strong adsorption of ssDNA to the surface of N-GQDs through π-π stacking interactions, resulting in the effective fluorescence quenching of N-GQDs system. The ssDNA underwent an irreversible cleavage event via the oxidative effect of BLM with Fe(II) as a cofactor, thus a turn-on fluorescence signal was observed. Thereby, the concentration of BLM can be quantitatively determined in a broad range from 0.34 nmol/L to 1300 nmol/L with a detection limit of 0.34 nmol/L. The presented method was applied to the determination of BLM in human serum samples with satisfactory results.
       
  • Benzophenone used as the photochemical reagent for pinpointing C=C
           locations in unsaturated lipids through shotgun and liquid
           chromatography-mass spectrometry approaches
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Tengfei Xu, Zifeng Pi, Fengrui Song, Shu Liu, Zhiqiang Liu Unsaturated lipids exhibit different physiological significances due to the different locations of the carbon–carbon double bond (C=C). Identifying lipid isomers with mass-based methods remains challenging. Xia's group has been successfully employed Paternò–Büchi (PB) reaction, a photochemical reaction with UV irradiation, coupled with tandem mass spectrometry (MS/MS) to identify and quantify unsaturated lipids in complex mixtures. However, the existing PB reagents possess certain demerits. In this regard, a new PB reagent that is compatible with various lipidomic analysis platforms must be screened. In this study, we comprehensively evaluated the conditions of the PB reaction and screened benzophenone as a new PB reagent. Benzophenone possesses unique advantages, such as a relative high PB yield; the PB products could be readily distinguished from the reacted lipids based on the added high molecular weight (182 Da); and the benzophenone does not affect the lipids appearance interval for reversed-phase column separation. Furthermore, we optimized the reaction conditions by using benzophenone as a PB reagent and summarized the molecular formulas of the diagnostic ions according to the fragment rules. The proposed PB method has been implemented in shotgun and LC–MS lipidomics. To our best knowledge, this work is the first to report the integrated PB reaction with LC–MS lipidomics for identification of lipid isomers.Graphical abstractImage 1
       
  • Based on ZnSe quantum dots labeling and single particle mode ICP-MS
           coupled with sandwich magnetic immunoassay for the detection of
           carcinoembryonic antigen in human serum
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Yupin Cao, Guichun Mo, Jinsu Feng, Xinxin He, Lifu Tang, Chunhe Yu, Biyang Deng A highly sensitive sandwich-type magnetic immunoassay based on inductively coupled plasma mass spectrometry detection in single particle mode, with ZnSe Quantum dots (QDs) serving as model tags, was proposed. The transient signals induced by the flash of ions (64Zn+) in the plasma torch from the ionization of nanoparticles tagged on antibody were recorded in a single particle mode. The frequency of transient signals is directly related to the concentration of nanoparticle tags, and the concentration of nanoparticle tagged antibodies can be quantified by the frequency of transient signals. Amino-modified magnetic nanoparticles (AMNPs) were synthesized and conjugated with primary carcinoembryonic antigen (CEA) antibody to extract the target biomarker. ZnSe QDs were synthesized as a probe to determine CEA by ICP-MS. A detection limit of 0.006 ng mL−1 was obtained for CEA after immunoreactions, and a wide linear range of 0.02–100 ng mL−1 with the relative standard deviation (RSD) was 4.4%. The method was successfully applied to human serum samples.Graphical abstractImage 1
       
  • Use of exogenous volatile organic compounds to detect Salmonella
           in milk
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Najat H.O. Bahroun, John D. Perry, Stephen P. Stanforth, John R. Dean Rapid, sensitive, and selective detection and identification of pathogenic bacteria is required in terms of food security. In this study, exogenous VOCs liberated by Salmonella strains have been identified and quantified via head space-solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) in milk samples. The specific enzymes targeted for detection and/or differentiation of Salmonella were C8 esterase, α-galactosidase and pyrrolidonyl peptidase using the following enzyme substrates: 2-chlorophenyl octanoate, phenyl α-d-galactopyranoside and L-pyrrollidonyl fluoroanilide, respectively. Detection of the exogenous VOCs, 2-chlorophenol, phenol and 3-fluoraniline was possible with typical limits of detection of 0.014, 0.045 and 0.005 μg/mL, respectively and correlation coefficients>0.99. The developed methodology was able to detect and identify Salmonella species within a 5 h incubation at 37 °C by the detection of the liberated VOCs. It was found that the milk samples tested were Salmonella free.Graphical abstractImage 1
       
  • Modern data science for analytical chemical data – A comprehensive
           review
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Ewa Szymańska Efficient and reliable analysis of chemical analytical data is a great challenge due to the increase in data size, variety and velocity. New methodologies, approaches and methods are being proposed not only by chemometrics but also by other data scientific communities to extract relevant information from big datasets and provide their value to different applications. Besides common goal of big data analysis, different perspectives and terms on big data are being discussed in scientific literature and public media. The aim of this comprehensive review is to present common trends in the analysis of chemical analytical data across different data scientific fields together with their data type-specific and generic challenges. Firstly, common data science terms used in different data scientific fields are summarized and discussed. Secondly, systematic methodologies to plan and run big data analysis projects are presented together with their steps. Moreover, different analysis aspects like assessing data quality, selecting data pre-processing strategies, data visualization and model validation are considered in more detail. Finally, an overview of standard and new data analysis methods is provided and their suitability for big analytical chemical datasets shortly discussed.Graphical abstractImage 1
       
  • Outside Front Cover
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s):
       
  • Characterization of polymer-coated CdSe/ZnS quantum dots and investigation
           of their behaviour in soil solution at relevant concentration by
           asymmetric flow field-flow fractionation – multi angle light scattering
           – inductively coupled plasma - mass spectrometry
    • Abstract: Publication date: 22 October 2018Source: Analytica Chimica Acta, Volume 1028Author(s): Stéphane Faucher, Gaëlle Charron, Elias Lützen, Philippe Le Coustumer, Dirk Schaumlöffel, Yann Sivry, Gaëtane Lespes A careful separation, identification and characterization of polymer-coated quantum dots (P-QDs) in complex media such as soil solution is the key point to understand their behaviour and to accurately predict their fate in the environment. In the present study, a synthesized CdSe/ZnS core/shell P-QDs suspension, proved to be stable for at least six months, was investigated with respect to P-QDs dimension, structure and elemental composition. Separation of P-QDs and size distribution determination were carried out by Asymmetric Flow Field-Flow Fractionation (AF4) - Multi Angle Light Scattering (MALS). AF4 and MALS were coupled to Inductively Coupled Plasma-Mass Spectrometry (ICPMS) as a selective and sensitive technique for the detection and the characterization of metallic and metalloid analytes. The exploration of element-specific data obtained by ICPMS after AF4 separation enabled the signal to be deconvoluted reliably. Thus, 3 classes of size populations were identified from the whole population of P-QDs. Additionally, a soil solution and a mix of P-QDs suspension with soil solution were characterized by the same method. This strategy enabled the P-QD population, which interacted with the soil solution, to be determined, this interaction leading either to an aggregation or dissolution of the P-QDs. Reproducibility and recovery of the size distributions and element concentrations were examined for each sample. Complementarily, Dynamic Light Scattering (DLS) and Scanning Transmission Electron Microscopy (STEM) were used jointly with AF4-MALS-ICPMS in order to demonstrate all potentialities of this coupling technique.Graphical abstractImage 1
       
  • Development of a self-priming PDMS/paper hybrid microfluidic chip using
           mixed-dye-loaded loop-mediated isothermal amplification assay for
           multiplex foodborne pathogens detection
    • Abstract: Publication date: Available online 12 July 2018Source: Analytica Chimica ActaAuthor(s): Bo Pang, Kaiyue Fu, Yushen Liu, Xiong Ding, Jiumei Hu, Wenshuai Wu, Kun Xu, Xiuling Song, Juan Wang, Ying Mu, Chao Zhao, Juan Li Foodborne pathogen is the primary cause of foodborne disease outbreak. Given its great damage, a sensitive, simple and rapid detection method is demanded. Herein, we described a self-priming polydimethylsiloxane (PDMS)/paper hybrid microfluidic chip, termed SPH chip, with mixed-dye-loaded loop-mediated isothermal amplification (LAMP) for multiplex foodborne pathogens detection. Staphylococcus aureus (SA) and Vibrio parahaemolyticus (VP) were chosen to verify the novel method. Compared to other similar detection devices, the SPH chip required easier fabrication process, less operation steps and lower cost. Additionally, the reaction result, especially for the weak-positive reaction, could be judged more accurately and conveniently due to the use of mixed-dye. Without pre-enrichment of bacteria in the food contaminated sample, the limit of detection (LOD) reached down to 1000 CFU mL−1 with high specific. Additionally, for fully exploiting the potential of SPH chip, a conceptual eight-channel detection chip was also developed. Overall, the reliable and excellent result demonstrated that the novel method had great potential to be applied in the wider range of pathogens detection or disease diagnose, especially in some resource-limited area.Graphical abstractImage 1
       
  • Electrochemical screening of single nucleotide polymorphisms with
           significantly enhanced discrimination factor by an amplified ratiometric
           sensor
    • Abstract: Publication date: Available online 12 July 2018Source: Analytica Chimica ActaAuthor(s): Baoting Dou, Jin Li, Bingying Jiang, Ruo Yuan, Yun Xiang The detection of single nucleotide polymorphisms (SNPs) is of great clinical significance to the diagnosis of various genetic diseases and cancers. In this work, the development of an ultrasensitive ratiometric electrochemical sensor for screening SNP with a significantly enhanced discrimination factor is reported. The ferrocene (Fc) and methylene blue (MB) dual-tagged triple helix complex (THC) probes are self-assembled on the gold electrode to construct the sensing interface. The addition of the mutant p53 gene causes the disassembly of the THC probes with the release of the Fc-tagged sequence and the folding of the MB-labeled sequence into a hairpin structure, causing the change in the current response ratio of MB to Fc for monitoring the mutant p53 gene. Such ratio is dramatically enhanced by the toehold-mediated displacement reaction-assisted target recycling amplification with the presence of an assistance hairpin sequence. With the significant signal amplification and the advantageous specificity of the THC probes, sub-femtomolar detection limit and a highly enhanced SNP discrimination factor for the mutant p53 gene can be obtained. Besides, the proof-of-demonstration application of the sensor for diluted real samples has been verified, offering such sensor new opportunities for monitoring various genetic related diseases.Graphical abstractImage 1
       
  • Nitrogen doped chiral carbonaceous nanotube for ultrasensitive DNA direct
           electrochemistry, DNA hybridization and damage study
    • Abstract: Publication date: Available online 12 July 2018Source: Analytica Chimica ActaAuthor(s): Mengjing Cui, Qiuyue Zhao, Qi Zhang, Mingxuan Fu, Yuexian Liu, Xinyu Fan, Haiyang Wang, Yufan Zhang, Huan Wang In the interest of developing novel electrocatalyst for high performance DNA biosensing, with distinctive chiral double helix nanostructure, nitrogen doped chiral carbonaceous nanotube (Chiral-CNT) was employed for ultrasensitive label-free DNA biosensing research. Chiral-CNT can quantitative detection of four DNA bases with high sensitivity and selectivity. Without any prehydrolysis and labeling process, direct electrochemistry of single-stranded DNA and double-stranded DNA, qualitative and quantitative detection of DNA hybridization (low detection limit: 0.0268 g L-1) were realized. Moreover, sensitive detection of DNA damage induced by fenton reagent was also realized with low detection limit of 0.0350 mg mL-1 and high sensitivity of 7.42 μA mg mL-1. The high biosensing performance attributes to the unique chiral structure of Chiral-CNT, leads to efficient interreaction between Chiral-CNT and DNA molecule.Graphical abstractUltrasensitive label-free DNA direct electrochemistry, DNA hybridization and damage study based on nitrogen doped chiral carbonaceous nanotube. Image 1
       
  • Direct sample injection from a syringe needle into a separation capillary
    • Abstract: Publication date: Available online 12 July 2018Source: Analytica Chimica ActaAuthor(s): František Opekar, Petr Tůma An automatic micro-injector was developed for electrophoretic analysis of a microlitre amount of clinical samples, enabling injection of the sample from a Hamilton syringe. The outlet of the syringe needle is located directly opposite the inlet of the separation capillary at a defined distance of the order of hundreds of μm in the injection space. During the injection, the background electrolyte is forced out by air from this space and a drop of the sample is forced out of the syringe by a micro-pump so that it is caught at the entrance to the capillary. From the drop the sample is injected into the capillary by applying a negative pressure pulse or simply by spontaneous injection. The injection space is then filled with background electrolyte, which washes away excess sample and separation is commenced. The injector was tested in electrophoretic separation of a model sample with equimolar concentrations of 100 μM NH4+, K+, Na+, Mg2+ and Li+ in a short capillary with total/effective length of 16.5/11.5 cm. The repeatability of the migration time and peak area expressed as the RSD value is 2% and 4%, respectively. The practical applicability of the injector was verified on the determination of the antiparasitic pentamidine in 10 μL of rat plasma. Electrophoretic separation of pentamidine was performed in 100 mM of acetic acid/NaOH at pH 4.55, the sample consumption per analysis is 125 nL, the separation time is 45 s and the attained LOQ using contactless conductivity detection is 8 μM.Graphical abstractImage 1
       
  • Hairpin-structured probe conjugated nano-graphene oxide for the cellular
           detection of connective tissue growth factor mRNA
    • Abstract: Publication date: Available online 11 July 2018Source: Analytica Chimica ActaAuthor(s): Min Wang, Christian Wiraja, Meiling Wee, David Yeo, Lianzhe Hu, Chenjie Xu Identification of abnormal scars at their early stage has attracted increasing attentions as the scars can only be assessed qualitatively and subjectively upon maturity, when no invasive procedure is involved. This report introduces a fluorescent probe that targets a potential abnormal scar biomarker (connective tissue growth factor (CTGF) mRNA) in skin fibroblasts. This probe is constructed of hairpin-structured probes (HPs) targeting CTGF mRNA and the nano-graphene oxide (nano-GO) base. The HPs are non-covalently absorbed on the surface of nano-GO, which pre-quenches the fluorescence of HPs. Close proximity of complementary CTGF mRNA would lead to preferential HP hybridization and dissociation from nano-GO, which restores the fluorescence signal from HPs. Utilizing this probe, we can distinguish abnormal fibroblasts derived from abnormal scars and assess the effectiveness of anti-scarring drugs like Repsox and transforming growth factor-beta type I receptor (TGF-βRI) siRNA.Graphical abstractA nano-graphene oxide-based probe targeting connective tissue growth factor (CTGF) mRNA was constructed for distinguishing abnormal scar fibroblasts and assessing the effectiveness of anti-scarring drugs including Repsox and specific siRNA.Image 1
       
  • Point discharge microplasma reactor for high efficiency conversion of H2S
           to SO2 for speciation analysis of sulfide and sulfite using molecular
           fluorescence spectrometry
    • Abstract: Publication date: Available online 11 July 2018Source: Analytica Chimica ActaAuthor(s): Huimin Yu, Jing Hu, Xiaoming Jiang, Xiandeng Hou, Yunfei Tian A low temperature plasma integrating the merits of small size, simple operation and rich active particles has good performance in analytical chemistry. In this work, a point discharge microplasma was used as a reactor to facilitate the gaseous conversion reaction from H2S to SO2 with an excellent efficiency as high as 95%. By coupling this reactor with a fluorescence spectrometer, the speciation analysis of sulfide and sulfite was achieved in a simple, chromatographic separation-free, time-saving and practical way. Specifically, with the discharge off, only sulfite was quantified; with discharge on, both sulfide and sulfite were quantified; and with a simple subtraction, the speciation analysis could be easily attained. By the acidification process, a limit of detection of 7.7 μM by the proposed method was obtained for both sulfide and sulfite in aqueous medium, and this method was successfully utilized to analysis of real samples.Graphical abstractThe speciation analysis of H2S and SO2 can be easily achieved with a point discharge on/off for sampling into a fluorescence spectrometer.Image 1
       
  • A New Bifunctional Nanostructure Based on Two‐Dimensional Nanolayered of
           Co(OH)2 Exfoliated Graphitic Carbon Nitride as a High Performance
           Enzyme-Less Glucose Sensor: Impedimetric and Amperometric Detection
    • Abstract: Publication date: Available online 11 July 2018Source: Analytica Chimica ActaAuthor(s): Javad Tashkhourian, Sayedeh Fatemeh Nami-Ana, Mojtaba Shamsipur A novel non-enzymatic glucose sensor was constructed based on the nanolayered Co(OH)2 deposited on polymeric graphitic carbon nitride (Co(OH)2-g-C3N4) via chemical bath deposition. The two‐dimensional nanocomposite was used to modify a carbon paste electrode and its electrochemical performance of electrode was carefully evaluated. The electrochemical oxidation of glucose at modified electrode was studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 0.2 M KOH. It revealed a remarkable electrocatalytic behavior and noticeably synergistic effect as a result of decent exfoliation of graphitic carbon nitride in the presence of Co(OH)2. The amperometric response achieved by the modified electrode showed two calibration ranges with an excellent selectivity. A single-frequency impedance method was applied for glucose determination as an alternative to conventional EIS methods. The developed sensor represents a high sensitivity, wide concentration range (25 μM - 420.0 mM by impedimetry and 6.6-9800 μM by amperometry), and high reproducibility. The modified electrode showed a good selectivity for glucose over potentially interfering materials such as dopamine, ascorbic acid, urea, and uric acid. Finally, the Co(OH)2-g-C3N4-CPE was utilized for quantification of glucose in blood serum samples.Graphical abstractImage 1
       
  • A photoswitchable “host-guest” approach for the selective enrichment
           of dimethoate from olive oil
    • Abstract: Publication date: Available online 11 July 2018Source: Analytica Chimica ActaAuthor(s): Raquel Garcia, Elisabete P. Carreiro, João P. Prates Ramalho, Anthony J. Burke, João C. Lima, Marco D.R. Gomes da Silva, Ana Maria Costa Freitas, Maria João Cabrita This work describes the development of a new selective photocontrollable molecularly imprinted-based sorbent for the selective enrichment/pre-concentration of dimethoate from spiked olive oil samples. To achieve this goal an improved molecularly imprinted strategy relying on the embedding of a functional monomer containing an azobenzene chromophore as light-responsive element, on the crosslinked tridimensional molecular imprinted network, has been assessed. To address the mechanisms underlying template recognition and uptake/release of the analyte from the functional imprinted material, computational studies using a quantum chemical approach, have been explored. This new functional sorbent provides a straightforward controllable uptake/release of the target template using light as the stimuli tool, which is highly advantageous due to light manipulation characteristics, such as superior clean, precision and remote controllable properties. In general, this work will contribute to the implementation of a photoswitchable analytical methodology that proves to be suitable for the selective isolation and further quantification of dimethoate from spiked olive oil matrices at levels similar to the maximum residues limits imposed by the legislation. The limits of detection, calculated based on 3σ, was 1.6 mgL−1 and the limit of quantification, based on 10σ, was 5.2 mgL−1. The implemented sample preparation shows high reproducibility and recoveries (93.3 ± 0.4%).Graphical abstractImage 1
       
  • Dual-functional polymer-modified magnetic nanoparticles for isolation of
           lysozyme
    • Abstract: Publication date: Available online 11 July 2018Source: Analytica Chimica ActaAuthor(s): Mingming Zhang, Juan Qiao, Li Qi An artificial receptor approach for proteins capture and release was designed based on ionic-sensitive and thermo-sensitive functionalized polymers, which were modified onto the surface of magnetic nanoparticles. The dual-functional poly(styrene-sulfonate-N-isopropylacrylamide) (P(SS-NIPAm)) was synthesized via the free radical polymerization method and used as the artificial receptor with electrostatic, hydrophilic and hydrophobic properties. The affinity between the artificial receptor and lysozyme was investigated using high performance liquid chromatography. Arising from the strong and specific interactions between the negatively charged sulfonic acid groups of P(SS-NIPAm) and positively charged amino groups of the protein, the prepared artificial receptor exhibited outstanding affinity for lysozyme. Interestingly, due to the thermo-responsive and ionic strength-responsive features of the prepared P(SS-NIPAm), the capture and release process for lysozyme could be modulated by varying the environmental temperature and ionic strength. Further, the proposed artificial receptor based on P(SS-NIPAm) modification of magnetic nanoparticles surface was used for affinity capture of lysozyme in human serum with a recovery ranging from 89.9% to 100.4%, paving a new way for synthesis of artificial receptors and showing great potential for recognition of target protein in real bio-samples.Graphical abstractImage 1
       
  • ε-MnO2-modified graphite electrode as a novel electrochemical sensor for
           the ultrasensitive detection of the newly FDA approved Hepatitis C
           antiviral drug ledipasvir
    • Abstract: Publication date: Available online 11 July 2018Source: Analytica Chimica ActaAuthor(s): Fatma A.M. Abdel-aal, Azza H. Rageh, Mohamed I. Said, Gamal A. Saleh A novel, simple and sensitive electrochemical method for the determination of ledipasvir (LED), the newly FDA approved Hepatitis C antiviral drug was developed and validated using ε-MnO2-modified graphite electrode. Two different MnO2 polymorphs (γ- and ε-MnO2 nanoparticles) were synthesized and characterized using X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), energy dispersive X-ray (EDX) and thermogravimetric analysis (TGA). Surface area measurements show that ε-MnO2 NPs have large surface area of 345 m2/g, which is extremely high if compared to that of γ-MnO2 NPs (38 m2/g). In addition, a comprehensive study of the difference in the electrochemical behavior of LED while using pencil graphite electrode (PGE) modified with either γ- or ε-MnO2 NPs is carried out. It was found that surface area and percentage of surface hydroxyls of MnO2 NPs are the key factors governing the sensitivity of the fabricated electrode toward the oxidation of the positively charged LED. Scanning electron microscopy (SEM) was employed to investigate the morphological shape of MnO2 NPs and the surface of the bare and modified electrodes. Moreover, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were used for the surface analysis of the modified electrodes. Based on the obtained results, ε-MnO2/PGE was applied as a selective and sensitive electrode for determination of LED. Under the optimized experimental conditions, ε-MnO2/PGE provides a linear response over the concentration range of 0.025–3.60 μmol L−1 LED with a low limit of detection, which was found to be 5.10 nmol L−1 (4.50 ng mL−1) for the 1st peak and 9.20 nmol L−1 (8.10 ng mL−1) for the 2nd one. In addition, the oxidation behavior of LED is discussed with a full investigation of the oxidized product using FT-IR and LC/MS. The fabricated sensor exhibits a good precision, selectivity and stability and was applied successfully for the determination of LED in its tablets and real rat plasma samples with a good recovery using a simple extraction technique.Graphical abstractImage 1
       
  • LED based near infrared spectral acquisition for multiwavelength
           analytical ultracentrifugation: A case study with gold nanoparticles
    • Abstract: Publication date: Available online 11 July 2018Source: Analytica Chimica ActaAuthor(s): Joseph Pearson, Helmut Cölfen A pulsed light emitting diode, coupled with a properly configured spectrometer is implemented in open source analytical ultracentrifugation detection hardware, allowing for spectral acquisition spanning the visible to near infrared. Details of the challenges arising with the new hardware are described, along with the necessary solutions to overcome them. The system is successfully tested with polystyrene and gold nanoparticles, demonstrating effectiveness for different material and particle geometries. Sedimentation coefficient distributions and analytically extracted spectra are presented for the multiwavelength datasets extending into the near infrared. Additionally, deconvolution algorithms are applied as a further demonstration of tools applicable to these datasets and the resolving power possible. The results of gold nanoparticle analysis presented here show effective near infrared spectral acquisition is now possible for multiwavelength analytical ultracentrifugation, opening the door for analysis of many important samples with spectral properties in this range, including rich classes of metal and semiconductor nanoparticles.Graphical abstractImage 1
       
  • Core-shell red silica nanoparticles based immunochromatographic assay for
           detection of Escherichia coli O157:H7
    • Abstract: Publication date: Available online 9 July 2018Source: Analytica Chimica ActaAuthor(s): Chunjie Zhu, Guangying Zhao, Wenchao Dou In this paper, a new type immunochromatographic assay (ICA) based on core-shell red silica nanoparticles (core-shell red SiO2NPs) was proposed and used to detect Escherichia coli O157:H7 (E. coli O157:H7). This is the first report of qualitative ICA for detecting E. coli O157:H7 in phosphate buffer saline (PBS) and food sample using core-shell red SiO2NPs. Monodispersed red SiO2NPs were synthesized in the aqueous solution by modifying amino silane and C.I Reactive Red 136 on unmodified silica nanoparticles. The limit of detection (LOD) of this core-shell red SiO2NPs based ICA for E. coli O157:H7 was 4.5 × 105 CFU/mL in sterile PBS within 20 min. The LOD of this ICA strip for E. coli O157:H7 in milk and pork samples both were 4.5 × 106 CFU/mL. The core-shell red SiO2NPs based ICA for detection of E. coli O157:H7 has no cross activity with other bacteria. All these results show that this new kind of core-shell colored SiO2NPs is promising for the practical applications in ICA and other rapid detection fields.Graphical abstractAn immunochromatographic strip based on core-shell red silica nanoparticles (core-shell red SiO2NPs) for detection of Escherichia coli O157:H7 (E. coli O157:H7) was developed. It was based on sandwich reaction between the capture antibody (test line), E. coli O157:H7 and core-shell red SiO2NPs labeled antibody. When there is E. coli O157:H7 in the sample, red band would appear both at test and control line. Otherwise, no color or reduced red color intensity at the test line compared with the positive sample.Image 1
       
  • Simultaneous observation of concurrent two-dimensional carbon and
           chlorine/bromine isotope fractionations of halogenated organic compounds
           on gas chromatography
    • Abstract: Publication date: Available online 6 July 2018Source: Analytica Chimica ActaAuthor(s): Caiming Tang, Jianhua Tan It has been reported that isotope fractionation can occur on gas chromatography (GC), yet little is known about concurrent dual-elements isotope fractionations on GC. Revelation of concurrent two-dimensional carbon and chlorine/bromine isotope fractionations of halogenated organic compounds (HOCs) on GC may be of important significance for compound-specific isotope analysis (CSIA). This study presents an in-depth investigation of the two-dimensional C and Cl/Br isotope fractionations of HOCs on GC using GC-double focus magnetic-sector high resolution mass spectrometry (GC-DFS-HRMS). The two-dimensional C and Cl/Br isotope fractionations of four organochlorines and four bromobenzenes on GC were simultaneously measured by GC-DFS-HRMS. The isotope fractionations were evaluated with isotope ratios, relative variations of isotope ratios (△hE) and isotope fractionation extents (ΛhE). All the HOCs exhibited significant inverse C and Cl/Br isotope fractionations, with Λ13C of 38.14‰–307.56‰, Λ37Cl of 59.60‰–146.85‰, and Λ81Br of 25.89‰–142.10‰. The isotope fractionations were significant in both ends of chromatographic peaks, while the isotope ratios in center retention-time segments were the closest to comprehensive isotope ratios in the whole peaks. Significant correlations between C isotope fractionation and Cl/Br isotope fractionation were observed, indicating that the isotope fractionations might have strong relationships and/or be dominated by similar factors. Relevant mechanisms for the two-dimensional C and Cl/Br isotope fractionations were tentatively proposed on basis of a modified two-film model and the theories related to zero point energy. The results of this study gains new insights into concurrent two-dimensional isotope fractionation behaviors of HOCs during physical processes, and are conducive to CSIA studies involving C, Cl and Br for obtaining high-quality data, particularly to dual-elements CSIA of C and Cl/Br.Graphical abstractImage 1
       
  • A highly conductive thin film composite based on silver nanoparticles and
           malic acid for selective electrochemical sensing of trichloroacetic acid
    • Abstract: Publication date: Available online 6 July 2018Source: Analytica Chimica ActaAuthor(s): R.M. Bashami, M. Tahir Soomro, Amna N. Khan, Elham S. Aazam, Iqbal M.I. Ismail, M.S. El-Shahawi A highly conductive thin film composite based on silver nanoparticles (AgNPs) and malic acid (MA) was deposited on glassy carbon electrode (GCE) for the selective and sensitive electrochemical sensing of trichloroacetic acid (TCA). The casting solution containing MA functionalized AgNPs was employed as a precursor for the thermal deposition of the AgNPs integrated MA thin film composite onto the GCE surface. The uniform coverage of AgNPs within the thin film composite at GCE was obtained by field emission scanning electron microscopy (FESEM). A significantly high charge transfer resistance of the modified electrode (85.7 Ω for AgNPs-MA/GCE in 2 mM [Fe(CN)6]3-/4- at a bias of +0.235 V as compared to bare GCE (38.01 Ω) verified the optimum coating of AgNPs-MA composite at the surface of the electrode. The AgNPs-MA composite deposited GCE revealed substantial electrocatalytic activity toward TCA reduction with significantly enhanced reduction current. The novel electrode manifested a linear square wave voltammetric (SWV) response over the concentration ranges of 0.1-2 (R2 = 0.9953) and 4-100 μM (R2 = 0.9969) with a limit of detection (LOD) and limit of quantification (LOQ) of 30 nM and 92.5 nM, respectively. The modified electrode exhibited an excellent long-term stability (30 days) with the retention of>95% of initial current. The selectivity of the proposed electrode for the determination of TCA was examined in the presence of dichloroacetic acid (DCA) and monochloroacetic acid (MCA) with the retention of high recovery percentages.Graphical abstractSchematic representation of reduction of TCA and its immediate reduction products at AgNPs-MA/GCEImage 1
       
  • Curcumin-graphene quantum dots for dual mode sensing platform:
           electrochemical and fluorescence detection of APO e4, responsible of
           Alzheimer's disease
    • Abstract: Publication date: Available online 6 July 2018Source: Analytica Chimica ActaAuthor(s): Abdelmoneim Mars, Maroua Hamami, Linda Bechnak, Digambara Patra, Noureddine Raouafi New dual electrochemical and fluorescence sensitive curcumin-graphene quantum dots sensing platform coated on the transparent Indium-Tin-Oxide electrode was developed to sense APO e4 DNA, responsible of Alzheimer's disease. Curcumin molecule with its dual fluorescence and electrochemical properties was electropolymerized on GQDs-ITO surface. EDC/NHS chemistry was used to covalently immobilize an amino-substituted DNA probe via a malonic acid spacer. Quenching of curcumin signals following hybridized DNA complex was employed to quantify APO e4 DNA. Amperometric studies revealed an ultrasensitive behavior toward the formation of DNA complex with a sensitivity of 4.74 nA.mL.pg –1 and a limit of detection as low as 0.48 pg mL –1. The platform exhibits very good performances such as repeatability, reproducibility, selectivity and long storage stability. Fluorescence results were established for the support and the complementarity of electrochemical results. Founded results confirmed the ultrasensitivity of platform with comparable performances. Recorded results in human blood plasma demonstrated the high efficacy of curcumin system sensing even in the clinical matrix.Graphical abstractImage 1
       
  • Ultrasensitive quantitative detection of small molecules with rapid
           lateral-flow assay based on high-affinity bifunctional ligand and magnetic
           nanolabels
    • Abstract: Publication date: Available online 6 July 2018Source: Analytica Chimica ActaAuthor(s): Sergey L. Znoyko, Alexey V. Orlov, Averyan V. Pushkarev, Elizaveta N. Mochalova, Natalia V. Guteneva, Afanasy V. Lunin, Maxim P. Nikitin, Petr I. Nikitin An ultrasensitive lateral-flow assay is developed for rapid quantitative detection of small molecules on-site. The conceptual novelty, which transfers lateral-flow assays to the category of highly sensitive quantitative systems, is due to employment of a bifunctional ligand combined with volumetric registration of magnetic nanolabels. The ligand provides extremely high affinity for trapping the nanolabels and, simultaneously, efficiently competes with the analyzed molecules for the limited quantity of antigen-binding sites on the nanolabels. The developed assay has been demonstrated as the first express method for measuring in human serum of free thyroxine (fT4). The limit of detection is 20 fМ or 16 fg/ml at the assay time
       
  • Flavanols react preferentially with quinones through an electron transfer
           reaction, stimulating rather than preventing wine browning
    • Abstract: Publication date: Available online 6 July 2018Source: Analytica Chimica ActaAuthor(s): Lingjun Ma, Andrew L. Waterhouse Wine oxidation changes the chemistry, sensory profile and color of wines. In wine oxidation, phenolics are oxidized to quinones and these reactive compounds can be quenched by sacrificial nucleophiles, such as the A-ring on flavanoids, preventing oxidative damage from the loss of desirable flavor molecules. The “catechol” B-ring on flavanoids, in contrast, can be oxidized by quinones through electron transfer reactions that lead to flavanoid quinones, precursors of browning products. Here we compared the rate of flavanoids reacting by either nucleophilic quinone quenching, or by electron transfer to generate flavanoid quinones. Our approach is based on mathematical modeling of reaction data to derive the rate constants of reactions of A-ring quenching vs B-ring electron transfer with caffeic acid quinone, by fitting the predicted loss of precursors and the appearance of products (or derivatives) with experimental data collected by LC/MS. The rate constant of the electron transfer reaction of caffeic acid quinone towards 4-methyl-catechol was fast (k4MC  = 3.43E-2 mLmol−1sec−1) but nucleophilic reactions with afzelechin (kAfz  = 2.53E-3 mLmol−1sec−1) or malvidin-3-glucoside (kMal  = 5.34E-3 mLmol−1sec−1), were much slower. No reaction was detected between caffeic acid quinone and isorhamnetin. Additionally, the electron transfer reaction rate of catechin and caffeic acid quinone was much faster at pH 7 (1.22E-02 mLmol−1sec−1) vs pH 3.5 (1.79E-03 mLmol−1sec−1). These results help explain why the reaction of catechin and caffeic acid quinone favors the formation of browning products, and more so at higher pH values. Furthermore, bisulfite reacted with quinones faster than the electron transfer reactions, preventing the browning observed in the reaction of catechin with caffeic acid quinone in the absence of bisulfite.Graphical abstractImage 1
       
  • Ultrasensitive and label-free electrochemical aptasensor of kanamycin
           coupling with hybridization chain reaction and strand-displacement
           amplification
    • Abstract: Publication date: Available online 6 July 2018Source: Analytica Chimica ActaAuthor(s): Ruijin Zeng, Lingshan Su, Zhongbin Luo, Lijia Zhang, Minghua Lu, Dianping Tang This work reports the proof-of-concept of an ultrasensitive label-free electrochemical aptasensor for Kanamycin (Kana) detection coupling strand-displacement amplification (SDA) with hybridization chain reaction (HCR). In the presence of target Kana, the analyte triggers conformational change of hairpin HP1 (HP1) and two-staged SDA to produce short single-stranded DNA (S1) with the aid of KF polymerase and nicking endonuclease. Meanwhile, the as-produced S1 hybridizes with the immobilized hairpin HP2 (HP2) on the electrode to open the hairpin, thereby resulting in the formation of DNA duplex. Thereafter, DNA duplex is selectively digested by Exo III accompanying S1 recycling. The residual single-stranded probe (S2) on the electrode opens another two hairpins in sequence and propagates a chain reaction of hybridization events between two alternating hairpins (H1 and H2) to form a long nicked double-helix. Upon addition of redox-active methylene blue (MB), numerous indicators are intercalated into the grooves of double-helix DNA polymers, each of which produces an electrochemical signal within the applied potentials. Under optimum conditions, the SDA/HCR-based electrochemical aptasensor exhibits a high sensitivity for detection of Kana down to 36 fM with a linear range from 0.05 to 200 pM. Additionally, the as-prepared aptasensor is successfully employed to determinate the Kana in animal derived food (milk). With the advantages of high sensitivity, label-free strategy and excellent selectivity, the developed aptasensor possesses great potential application value in food-safety analysis field.Graphical abstractImage 1
       
  • Fabricating carbon-nanotubes-based porous foam for superoxide
           electrochemical sensing through one-step hydrothermal process induced by
           phytic acid
    • Abstract: Publication date: Available online 6 July 2018Source: Analytica Chimica ActaAuthor(s): Xuan Cai, Kaicha Chen, Zhenxing Wang, Wenqian Sun, Hongli Zhao, Huanhuan Zhang, Huilan Chen, Minbo Lan The detection of superoxide anions (O2•−) is widely considered as a potential way for cancer diagnosis and the development of enzyme-mimic catalysts is the main challenge in the establishment of electrochemical sensors for O2•− sensing in real samples. Here we present a novel enzyme- and metal-free electrochemical catalyst for superoxide (O2•−) sensing based on the widely-used carbon nanotubes (CNT). Through a one-step hydrothermal process induced by phytic acid (PA), CNT-based porous foam (PACNTF) was successfully obtained. Characterizations demonstrated the enhanced defect and disorder degree of PACNTF after PA treatment, which leaded to the increased active sites of PACNTF for electron transfer and the adhesion of O2•− during the electrochemical process. As a result, the PACNTF presented higher conductivity and larger current response toward O2•− sensing when compared with CNT precursor and CNTF without PA treatment. The sensitivity of PACNTF/SPCE was calculated to be 1230 μA cm-2 mM-1 in the linear range of 0–193.6 μM (R2 = 0.965) and 373 μA cm-2 mM-1 in the linear range of 193.6–1153.6 μM (R2 = 0.995) with a limit of detection of 0.16 μM (S/N = 3). Further, the PACNTF/SPCE presented fast response toward cell-released O2•− stimulated by Zymosan A. The above results indicated that the fabricated sensor holds potential usage in biological samples.Graphical abstractImage 1
       
  • Aptamer proximity recognition-dependent strand translocation for
           enzyme-free and amplified fluorescent detection of thrombin via catalytic
           hairpin assembly
    • Abstract: Publication date: Available online 6 July 2018Source: Analytica Chimica ActaAuthor(s): Jing Li, Wenjiao Zhou, Ruo Yuan, Yun Xiang By coupling a new aptamer proximity recognition-dependent strand translocation strategy with catalytic hairpin assembly (CHA) signal amplification, we have developed a simple and sensitive method for detecting thrombin in human serums. Simultaneous binding of two engineered aptamer probes to the thrombin target significantly increases the local concentrations of the two probes and facilitates the translocation of a ssDNA strand from one of the probes to the other through toehold mediated strand displacement. Such a strand translocation leads to the generation of a ssDNA tail in the aptamer sequence for subsequent initiation of the assembly of two fluorescently quenched hairpins into many DNA duplexes via CHA. The formation of the DNA duplexes thus results in significant fluorescence recovery for amplified detection of thrombin down to 8.3 pM. The developed method is highly selective to the thrombin target against other interference proteins due to the dual recognition mode, and can be employed to monitor thrombin in human serum samples. With the advantage of simplicity, sensitivity and selectivity, this method can be a universal non-enzymatic and nanomaterial-free amplified sensing platform for detecting different protein molecules.Graphical abstractImage 1
       
  • Dual-mode fluorescent and colorimetric immunoassay for the ultrasensitive
           detection of alpha-fetoprotein in serum samples
    • Abstract: Publication date: Available online 5 July 2018Source: Analytica Chimica ActaAuthor(s): Yaofeng Zhou, Xiaolin Huang, Sicheng Xiong, Xiangmin Li, Shengnan Zhan, Lifeng Zeng, Yonghua Xiong We present a novel dual-mode fluorescent and colorimetric immunosensor based on conventional immunoassay platforms by utilizing a gold nanoflower (AuNF)-loaded fluorescein molecule (AuNF@Fluorescein) as signal output. The AuNFs were modified with thiolated carboxyl ligand, which consisted of a hydrophobic alkane chain as hydrophobic wallet for fluorescein encapsulation, a tetra (ethylene glycol) unit for biocompatibility and solubility, and a functional carboxyl group for the conjugation of biorecognition molecules for biosensing. The resultant AuNFs showed a high loading capacity of 3.74 × 106 fluorescein molecules per AuNF because of its flower-like shape with many complex branches. By adjusting the solution pH to 8.0, the fluorescein molecules can almost entirely be released from the hydrophobic wallet of AuNF@Fluorescein, which led to strong fluorescent-signal amplification. Under the optimal detection conditions, the proposed immunoassay based on fluorescent signal exhibited ultrahigh sensitivity for alpha-fetoprotein (AFP) detection, with a limit of detection (LOD) of 29 fg/mL. This value is approximately 9.3 × 103-fold lower than that of corresponding horseradish peroxidase (HRP)-based immunoassay (LOD = 270 pg/mL). The fluorescein molecule also had intrinsic peroxidase-like activity to catalyze 3,3′,5,5′-tetramethylbenzidine oxidation with hydrogen peroxide for colorimetric signal. The proposed method with colorimetric mode further exhibited a sensitivity with a LOD of 17.7 pg/mL, which is about 15-fold lower than that of conventional HRP-based immunoassay. The recoveries of the proposed dual-mode immunoassay for AFP spiked serum samples ranged within 89.85%–100.0%, with the coefficient of variations ranging from 0.5% to 2.4%, indicating acceptable accuracy and precision for AFP quantitative detection. The reliability of the developed dual-mode immunoassay was further compared with a commercial chemiluminescence immunoassay kit by analyzing 20 clinical serum samples, showing that the two methods well agreed with each other, with high correlation coefficients of 0.997 and 0.986 based on recorded fluorescence and colorimetric signals, respectively. In summary, the proposed method was highly suitable for the ultrasensitive analysis of biomarkers or infectious diseases by fluorescence mode and can be used for routine clinical diagnosis by colorimetric mode.Graphical abstractImage 1
       
  • Non-separative mass spectrometry methods for non-invasive medical
           diagnostics based on volatile organic compounds: A review
    • Abstract: Publication date: Available online 5 July 2018Source: Analytica Chimica ActaAuthor(s): Ana María Casas-Ferreira, Miguel del Nogal-Sánchez, José Luis Pérez-Pavón, Bernardo Moreno-Cordero In this review, an assessment of non-separative methods based on mass spectrometry used to analyse volatile organic compounds in the field of bioanalysis is performed. The use of non-separative methods based on mass spectrometry has been established as an attractive option for analysing compounds. These instrumental configurations are suitable for biomedical applications because of their versatility, rapid output of results, and the wide range of volatile organic compounds that can be determined.Here, techniques such as headspace sampling coupled to mass spectrometry, membrane introduction mass spectrometry, selected ion flow tube mass spectrometry, proton transfer reaction mass spectrometry, secondary electrospray ionization mass spectrometry and ion mobility mass spectrometry, are evaluated. Samples involving non-invasive methods of collection, such as urine, saliva, breath and sweat, are mainly considered. To the best of our knowledge, a comprehensive review of all the non-separative instrumental configurations applied to the analysis of gaseous samples from all matrices non-invasively collected has not yet been carried out.The assessment of non-separative techniques for the analysis of these type of samples can be considered a key issue for future clinical applications, as they allow real-time sample analysis, without patient suffering. Any contribution to the early diagnosis of disease can be considered a priority for the scientific community. Therefore, the identification and determination of volatile organic compounds related to particular diseases has become an important field or research.Graphical abstractImage 1
       
  • Ultra-high performance supercritical fluid chromatography in impurity
           control: Searching for generic screening approach
    • Abstract: Publication date: Available online 5 July 2018Source: Analytica Chimica ActaAuthor(s): Kateřina Plachká, František Švec, Lucie Nováková In this study, 63 compounds measured as 10 individual mixtures containing in each case an active pharmaceutical ingredient and its relevant impurities, and additional set of 7 basic beta blockers were analyzed using ultra-high performance supercritical fluid chromatography with UV and mass spectrometry detection. The separations were accomplished using 8 different stationary phases (diol, diethylamine, 2-picolylamine, 1-aminoanthracene, BEH 2-ethylpyridine, BEH, CSH pentafluorophenyl and HSS C18 SB), 6 modifiers (methanol, ethanol, isopropanol, methanol/acetonitrile, methanol/ethanol, ethanol/acetonitrile) and 5 additives in methanol (0.1% formic acid, 10 mmol/L ammonium formate, 10 mmol/L ammonium acetate, 0.4% ammonium hydroxide, and 2% water).Graphical abstractImage 1
       
  • Sensitive DNA detection by polymerase chain reaction with gold
           nanoparticles
    • Abstract: Publication date: Available online 5 July 2018Source: Analytica Chimica ActaAuthor(s): Li Zou, Ruidi Shen, Liansheng Ling, Gongke Li We developed a novel strategy for rapid colorimetric detection of specific DNA sequence based on gold nanoparticles assemblies induced by polymerase chain reaction (PCR) product. In the presence of target DNA, the two DNA-functionalized AuNP probes selectively hybridized with the prohibited nucleic acid segments of two primers owing to the zipping off of the hairpin structures during PCR process, resulted in the aggregation of AuNPs with a concomitant color change from red to blue-purple. It is a convenient and universal method for sensitive DNA detection with no need for any further post-treatment of the PCR products. Most importantly, our method showed a low limit of detection (LOD) of 4.3 fM with a wide range of target DNA from 16 fM to 1.6 nM. Owing to the versatility and low cost, the proposed strategy could be extremely useful for a wide range of applications, providing a promising tool for rapid disease diagnostics and gene sequencing.Graphical abstractImage 1Gold nanoparticles assemblies induced by PCR product are employed as a colorimetric biosensor for sensitive DNA detection.
       
  • A simple and sensitive fluorescence method for detection of telomerase
           activity using fusion protein bouquets
    • Abstract: Publication date: Available online 5 July 2018Source: Analytica Chimica ActaAuthor(s): Tao Wu, Yuanfu Zhang, Tingting Hou, Yinghong Zhang, Shuhao Wang Telomerase is considered as a widely accepted cancer biomarker for early cancer diagnostics. Herein, we develop a simple, ultrahigh sensitivity method for detection of telomerase activity, which relied on that RecA-GFP fusion proteins wrapped around telomeric DNA to form fluorescence bouquets. RecA-GFP fusion protein was synthesized through fusion protein technology. In the presence of telomerase, telomerase elongation products are wrapped around by RecA-GFP fusion protein to form big fluorescent bouquets, which resulted in strong fluorescence. This method has the linear range from 50 to 1000 HeLa cells and the detection limit is 8 HeLa cells, based on a signal-to-noise ratio (S/N) of 3. Compared with conventional methods, this method has the advantages of low toxicity, outstanding sensitivity, and excellent selectivity. Hence, it provides a promising approach for the detection of telomerase activity and diagnosis of cancer.Graphical abstractImage 1
       
  • Macro-mesoporous organosilica monoliths with bridged-ethylene and
           terminal-vinyl: High-density click functionalization for chromatographic
           separation
    • Abstract: Publication date: Available online 4 July 2018Source: Analytica Chimica ActaAuthor(s): Ci Wu, Yu Liang, Xudong Zhu, Qun Zhao, Fei Fang, Xiaodan Zhang, Zhen Liang, Lihua Zhang, Yukui Zhang A novel kind of macro-mesoporous organosilica monolith, with not only bridged-ethylene groups incorporated into the skeleton but also terminal-vinyl groups protruded from the pore-wall, was prepared so that high-loaded double bonds were achieved. Via highly efficient “thiol-ene” click reaction of such high-loaded double bonds, the surface coverage of C18 groups on monolith could be 5.54 μmol m−2, significantly larger than that of the reported separation materials, beneficial to improvement of separation resolution, especially for peptide separation. The separation performance was evaluated using alkylbenzenes and standard peptides. Furthermore, the tryptic digests of complex sample was successfully analyzed. Because of high separation resolution of our prepared hybrid monolith, the peak capacity for 6-h gradient was achieved as 482. Coupling to LTQ Orbitrap Velos Mass Spectrometry, 22523 tryptic peptides from 4423 proteins were identified from the HeLa cells, more than that using the other long-gradient separation by the same system reported, showing great promising of such monolith for large-scale in-depth proteomic analysis.Graphical abstractImage 1
       
  • A gold nanoparticle-based lateral flow biosensor for sensitive visual
           detection of the potato late blight pathogen, Phytophthora infestans
    • Abstract: Publication date: Available online 3 July 2018Source: Analytica Chimica ActaAuthor(s): Fangfang Zhan, Tian Wang, Linda Iradukunda, Jiasui Zhan Phytophthora infestans, the causal agent of late blight in potatoes and tomatoes, is the most important and ongoing pathogenic threat to agricultural production worldwide. Rapid and early identification of P. infestans is an essential prerequisite for countering the further spread of infection. In this study, a novel method for visual detection of P. infestans has been developed by integrating universal primer mediated asymmetric PCR with gold nanoparticle (AuNP)-based lateral flow biosensor. We employed asymmetric PCR to generate large amounts of single-stranded DNA (ssDNA) by amplifying a region of P. infestans-specific repetitive DNA sequence. The ssDNA products were then applied to the lateral flow biosensor to perform a visual detection using sandwich-type hybridization assays. In the presence of target DNA, sandwich-type hybridization reactions among the AuNP–probe, target DNA and capture probe were performed on the test line of the biosensor, and then a characteristic red band was produced for the accumulation of AuNPs. Quantitative analysis obtained by recording the optical intensity of the red band demonstrated that this biosensor could detect as little as 0.1 pg μL−1 genomic DNA. Furthermore, the specificity of the biosensor was confirmed by detecting three other Phytophthora species and two pathogenic fungi. We believe this method has potential application in early prediction of potato late blight disease and instigation of management actions to reduce the risk of epidemic development.Graphical abstractImage 1
       
  • Electrochemical recognition of nitrophenol isomers by assembly of
           pillar[5]arenes mutifilms
    • Abstract: Publication date: Available online 3 July 2018Source: Analytica Chimica ActaAuthor(s): Xiaoping Tan, Genfu Zhao, Xu Zhou, Taohong Li, Hong Lei, Guanben Du, Long Yang The rational design of electrochemical methods for isomer recognition is a focus of research in the molecular recognition and separation fields. In this work, a novel, rapid, and convenient electrochemical approach for recognition of nitrophenol isomers was constructed based on the alternating layer-by-layer (LbL) assembly of water-soluble cationic and anionic pillar [5]arene on a carboxylic graphene (C-Gra) modified glass carbon electrode. The electrochemical recognition of nitrophenol isomers was investigated by differential pulse voltammetry (DPV). The electrochemical results reveal that both the peak currents of m-nitrophenol (m-NP) and p-nitrophenol (p-NP) increased with the increasing of the layer number of the assembled pillar [5]arene, whereas the peak current of o-nitrophenol (o-NP) decreased with the increased layers, which demonstrated an efficient route for discriminating the nitrophenol isomers. The molecular recognition mechanism was studied by 1H NMR spectra, which indicated that the m-NP and p-NP can be included in the cavity of the pillar [5]arene host. However, the o-NP could not enter into the host of pillar [5]arene, which was ascribed to the formation of intramolecular hydrogen bond of o-NP. The LbL assembly modified GCE was used for detecting p-NP and m-NP. A low detection limit of 0.33 μM (S/N = 3) and a linear response range of 1–90 μM for p-NP were obtained by using this method. And the detection limit of 0.16 μM (S/N = 3) and a linear response range of 0.5–70 μM for m-NP were obtained. This method of LbL assembly modified GCE has potential application in molecular recognition and separation.Graphical abstractSchematic illustrating the layer by layer assembly of pillar[5]arenes mutilayer films for recognition of nitrophenol isomers.Image 1
       
  • A rapid LC-MS method for qualitative and quantitative profiling of plant
           apocarotenoids
    • Abstract: Publication date: Available online 3 July 2018Source: Analytica Chimica ActaAuthor(s): Jianing Mi, Kun-Peng Jia, Jian You Wang, Salim Al-Babili Carotenoid cleavage products (apocarotenoids; APOs) exert important biological functions in light perception and as vitamin A source, signaling molecules, hormone precursors, pigments and volatiles. However, an analytical method that allows simultaneous profiling of these diverse compounds is still missing. We developed an efficient method to analyze APOs present in plant tissues, which is based on ultra-high performance liquid chromatographic separation and high-resolution hybrid quadrupole-Orbitrap (Q-Orbitrap) mass spectrometry (MS). Our approach allowed unambiguous identification and quantification of volatile and non-volatile APOs in a single run. Modified sample preparation and optimized ultra-high performance liquid chromatography (UHPLC)-MS parameters permitted the measurement of APOs in Oryza sativa seedlings and Spinacia oleracea leaves, unraveling 20 endogenous APOs with chain lengths ranging from C10 to C30, confirmed by high-resolution MS, MS/MS data and using synthetic standards. Our experimentation demonstrates that the usage of methanol with 0.1% butylated hydroxytoluene facilitates the extraction of both short-chain and long-chain APOs from plant materials. In addition, our validated analytical method allows the quantitative analysis of APOs with a wide content range from 2.5 pg/mg to 10 ng/mg dried weight. The adoption of the analytical protocol, as described in this study, realizes the measurement of volatile APOs by using a LC-MS method, hence, allowing informative and reliable profiling of APOs, which is important for determining the content of these compounds in food and crucial for understanding their function and metabolism in plants.Graphical abstractImage 1
       
  • A novel malic acid-enhanced method for the analysis of
           5-methyl-2′-deoxycytidine, 5-hydroxymethyl-2′-deoxycytidine,
           5-methylcytidine and 5-hydroxymethylcytidine in human urine using
           hydrophilic interaction liquid chromatography-tandem mass spectrometry
    • Abstract: Publication date: Available online 3 July 2018Source: Analytica Chimica ActaAuthor(s): Cheng Guo, Cong Xie, Qin Chen, Xiaoji Cao, Mengzhe Guo, Shu Zheng, Yinsheng Wang 5-Methyl-2′-deoxycytidine (5-mdC), 5-hydroxymethyl-2′-deoxycytidine (5-hmdC), 5-methylcytidine (5-mrC) and 5-hydroxymethylcytidine (5-hmrC) are epigenetic marks of DNA and RNA, and aberrant levels of these modified nucleosides were found to be associated with various cancers. Urine is a preferred source of biological fluid for biomarker discovery because the sample collection process is not invasive to patients. Herein, we developed a novel malic acid-enhanced hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method for sensitive and simultaneous quantification of the modified cytosine nucleosides in human urine. Malic acid markedly increased the detection sensitivities of all four cytosine nucleosides, with the limits of detection (LODs) for 5-mdC, 5-hmdC, 5-mrC and 5-hmrC being 0.025, 0.025, 0.025 and 0.050 fmol, respectively. By using this method, we demonstrated, for the first time, the presence of 5-hmrC in human urine, and we successfully quantified 5-mdC, 5-hmdC, 5-mrC and 5-hmrC in urine samples collected from 90 patients with colorectal cancer (CRC) and 90 healthy controls. We found that the levels of 5-mdC, 5-hmdC, 5-mrC and 5-hmrC in urine were all substantially decreased in CRC patients, suggesting that these modified nucleosides might have great potential to be noninvasive biomarkers for early detection and prognosis of CRC. Together, we established a novel and sensitive method for detecting 5-methylated and 5-hydroxymethylated cytosine nucleosides in human urine and the results from this study may stimulate future investigations about the regulatory roles of these cytosine derivatives in the initiation and development of CRC.Graphical abstractImage 1
       
  • Ultra-performance supercritical fluid chromatography: A powerful tool for
           the enantioseparation of thermotropic fluorinated liquid crystals
    • Abstract: Publication date: Available online 3 July 2018Source: Analytica Chimica ActaAuthor(s): Petra Vaňkátová, Květa Kalíková, Anna Kubíčková A fast and simple supercritical fluid chromatography method for the enantioseparation of twenty newly synthesized orthoconic antiferroelectric liquid crystals is reported for the first time. The effects of alkoxy spacer length and fluorine atom presence and position in the phenyl ring on chromatographic behavior were investigated. Baseline enantioseparation of all compounds was achieved using simple mobile phases consisting of carbon dioxide and alcohol as cosolvent on (3,5-dimethylphenylcarbamate) derivative of amylose as chiral stationary phase. The analysis times ranged from 2 to 4 and from 4 to 7 min for most samples when using methanol and propane-2-ol, respectively. The significant effect of cosolvent type on the enantioseparation of these compounds was assessed and partial complementarity of methanol and propane-2-ol was observed.Graphical abstractImage 1
       
  • Determination of volatile fatty acids in digestate by solvent extraction
           with dimethyl carbonate and gas chromatography-mass spectrometry
    • Abstract: Publication date: Available online 3 July 2018Source: Analytica Chimica ActaAuthor(s): Michele Ghidotti, Daniele Fabbri, Cristian Torri, Sergio Piccinini Volatile fatty acids (VFAs) are among the most important parameters in process monitoring of anaerobic digestion plants for biogas production. The concentration of single VFA species is typically determined by direct injection of the acidified aqueous phase of digestate samples into GC-FID. Analysis of dimethyl carbonate extracts was investigated as an alternative method consisting of a simple and rapid in-vial procedure of acidification and solvent extraction of the sample, followed by centrifugation and GC-MS analysis. The principal figures of merit resulting from internal standard calibration were comparable to those proposed for the direct analysis of aqueous digestate, while the analysis of real samples did not provide statistically significant differences between the two methods according to parametric and non-parametric tests. Procedural aspects including sample amount and solid removal improved with dimethyl carbonate, while GC contamination was reduced. The method was applied to seventeen samples from fully operating anaerobic digesters fed with various feedstocks and enabled the individuation of high probability of system stress through the values of total VFA, propanoic acid, longer chained VFA concentrations and the ratio between acetic and propanoic acid concentrations. The use of dimethyl carbonate allowed the detection of alicyclic and aromatic acids that could represent new molecular markers in assessing the origin of feed and process conditions.Graphical abstractImage 1
       
  • A novel enzyme-free glucose and H2O2 sensor based on 3D graphene aerogels
           decorated with Ni3N nanoparticles
    • Abstract: Publication date: Available online 3 July 2018Source: Analytica Chimica ActaAuthor(s): Duanduan Yin, Xiangjie Bo, Jian Liu, Liping Guo In this work, a novel enzyme-free glucose and hydrogen peroxide (H2O2) sensor based on Ni3N nanoparticles on conductive 3D graphene aerogels (Ni3N/GA) has been successfully synthesized by using hydrothermal reaction, freeze-dried and then calcined under NH3 atmosphere. The obtained Ni3N/GA composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption isotherms and electrochemical methods. The results show the obtained 3D Ni3N/GA composites exhibit excellent electrochemical performance toward glucose oxidation and H2O2 reduction with larger catalytic rate constant Kcat value of 3.75 × 103 M−1 s −1 and 1.24 × 103 M−1 s −1, respectively. As a glucose sensor, the obtained electrode provides a wide detection range of 0.1–7645.3 μM, fast response time within 3 s, high sensitivity of 905.6 μA mM-1 cm-2 and low detection limit of 0.04 μM. For detection of H2O2, this prepared sensor offers a wide detection range (5 μM–75.13 mM), fast response time (within 5 s), sensitivity (101.9 μA mM-1 cm-2) and low detection limit (1.80 μM). This enzyme-free glucose and H2O2 sensor display satisfactory selectivity, reproducibility and long-term storage stability. Additionally, the sensor can also be used for glucose and H2O2 detection in human blood serum. The results demonstrate that 3D GA nanostructures provide an enviable conductive network for efficient charge transfer and avoid Ni3N nanoparticles aggregation, which is advantageous for electrocatalytic applications.Graphical abstractNi3N/GA composites were prepared and used to detect glucose oxidation and H2O2 reduction.Image 1
       
  • A highly sensitive peptide-based biosensor using NiCo2O4 nanosheets and
           g-C3N4 nanocomposite to construct amplified strategy for trypsin detection
           
    • Abstract: Publication date: Available online 2 July 2018Source: Analytica Chimica ActaAuthor(s): Yanyu Lin, Rongkai Shen, Nannan Liu, Huan Yi, Hong Dai, Jianhua Lin Here, a simple electrochemical biosensor was proposed based on the specific recognition between trypsin and peptide. Initially, NiCo2O4-PAMAM nanocomposite was casted on the bare electrode to achieve the electrochemical signal amplification in 0.1 mM [Ru(NH3)6]3+ solution owing to the great electronic conductivity and high electrochemical activity induced by the special structure of NiCo2O4 nanosheets (Ni3+ cations in octachedral sites of the Co3O4). Subsequently, a declined electrochemical signal was obtained when g-C3N4 labeled peptide composites were anchored on the electrode. However, after trypsin was added into solution and incubated with the biosensor, the electrochemical signal was re-promoted. Therefore, the as-synthesized biosensor could realize the sensitive detection of trypsin by virtue of the specific recognition between trypsin and peptide. As a result, the developed peptide-based exhibited a linear range from 10−10 to 10−4 mg mL−1 with an ultralow detection limit of 10−10 mg mL−1, providing sensitive analytical performance and acceptable application potential in clinical test and disease diagnosis due to its high stability, excellent selectivity, acceptable reproducibility and accurate signal output.Graphical abstractA peptide-based biosensor using NiCo2O4 nanosheets and amplified strategy for trypsin detection.Image 1
       
  • Phosphorus-doped graphene-based electrochemical sensor for sensitive
           detection of acetaminophen
    • Abstract: Publication date: Available online 30 June 2018Source: Analytica Chimica ActaAuthor(s): Xuan Zhang, Kai-Ping Wang, Li-Na Zhang, Yi-Chi Zhang, Li Shen Phosphorus-doped graphene (P-RGO) was synthesized and employed as active electrode material to construct electrochemical sensor for acetaminophen (AP). The P-RGO coated glass carbon electrode (P-RGO/GCE) showed an excellent electrocatalytic activity for the oxidation of AP, resulted from highly enhanced electrochemical conductivity and accelerated electron transfer. The experimental conditions for AP detection were optimized, and under the optimal condition, a linear relationship between current intensity and concentration of AP was obtained in the range of 1.5–120 μM with a detection limit of 0.36 μM (S/N = 3). The developed sensor showed high selectivity for AP in the presence of various common species, excellent reproducibility and stability. The present sensor was also successfully applied for AP detection in pharmaceutical tablet samples.Graphical abstractImage 1Phosphorus-doped graphene (P-RGO) was synthesized and employed as active electrode material to construct electrochemical sensor for acetaminophen detection in pharmaceutical tablet.
       
  • Integrated three-electrode screen-printed sensor modified with bismuth
           film for voltammetric determination of thallium(I) at the ultratrace level
           
    • Abstract: Publication date: Available online 30 June 2018Source: Analytica Chimica ActaAuthor(s): K. Domańska, K. Tyszczuk-Rotko In the present paper, for the first time, the integrated three-electrode screen-printed sensor with in situ plated bismuth film carbon working electrode was applied for the ultratrace determination of thallium(I) (Tl(I)). Under optimized conditions extremely low limits of detection were reached, 8.47 × 10−10 and 6.71 × 10−12 mol L−1 for the deposition times of 60 s and 300 s, respectively. The influences of foreign metal ions and surfactants on the voltammetric signal of thallium in natural samples were minimized using 1 × 10−5 mol L−1 EDTA and Amberlite XAD-7 resin added to the buffer solution (CH3COONH4, CH3COOH and NH4Cl) of pH = 4.6 ± 0.1. The developed voltammetric method with integrated three-electrode screen-printed sensor was validated with use of certified reference materials (surface, rain and natural water) and can be in future applied to field analyses of Tl(I).Graphical abstractImage 1
       
  • Enhanced catalytic capability of electroactive biofilm modified with
           different kinds of carbon nanotubes
    • Abstract: Publication date: Available online 30 June 2018Source: Analytica Chimica ActaAuthor(s): Zhaohong Jiang, Di Zhang, Lei Zhou, Dandan Deng, Min Duan, Ying Liu In this study two methods including coating carbon nanotubes (CNTs) layers on the electrode surface and adding CNTs-suspension during electrochemically active biofilms (EABs) growth were used, respectively, to develop CNTs hybrid EABs for enhancing electricity generation capability of EABs. EABs growth on the CNTs with functional groups of hydroxyl (CNTs-OH) or carboxyl (CNTs-COOH) and pristine CNTs without functionalization (P-CNTs) modified electrode was investigated. The maximum current densities of EABs growth on the P-CNTs, CNTs-OH and CNTs-COOH coated electrode were respective 1300 ± 117, 1082 ± 54 and 1124 ± 78 μA cm−2, which were much higher than unmodified electrode (663 μA cm−2). Meanwhile, EABs growth in doping CNTs-COOH or CNTs-OH suspensions system also produced twice higher current density than that on unmodified electrode. These results indicated that the current production of EABs can be significantly enhanced by coating P-CNTs, CNTs-OH, CNTs-COOH layers on the electrode surface or doping CNTs-OH and CNTs-COOH suspension into EABs. Furthermore, morphology analysis of as-obtained EABs had also been studied. It was found that there was no significant difference of the morphological characteristic for EABs growth on different types CNTs coated electrode surface. By comparison, a nano-hybrid porous structure of CNTs and EABs was observed when CNTs-COOH or CNTs-OH suspension was added into the medium during EABs growth, which will be responsible for high current generation.Graphical abstractImage 1
       
  • Cu(Ⅱ) triggering redox-regulated anti-aggregation of gold nanoparticles
           for ultrasensitive visual sensing of iodide
    • Abstract: Publication date: Available online 30 June 2018Source: Analytica Chimica ActaAuthor(s): Ruifeng Peng, Haibo He, Qian Wang, Xiaoxia Yan, Qiongwei Yu, Haixiao Qin, Yunyi Lei, Liqiang Luo, Yuqi Feng In this study, we proposed a novel anti-aggregation of gold nanoparticles (AuNPs) strategy for colorimetric sensing of iodide ions (I−) regulated by the redox reaction between the target ions and the ion cross-linking agent. Cu2+ as interlinking ion can induce aggregation of arginine capped AuNPs (Arg-AuNPs) due to the formation of Arg-Cu2+-Arg analogous structure resulting from the chelation between Cu2+ and arginine, with a clear color change of solution from red to blue. In the presence of I−, however, Cu2+ would be readily reduced owing to the formation of CuI, AuNPs underwent a transformation from an aggregation to a dispersion state depending on the concentration of I−, leading color changes from blue to red. The corresponding color variation in the process of anti-aggregation of AuNPs can be monitored through UV–vis spectrophotometer or by the naked-eye, making quantitative analysis of I− feasible in a convenient colorimetric or visual way. The assay only took 5 min, showing high sensitivity with a lowest detectable concentration of 10 nM and excellent selectivity for I− over other anions tested, which was successfully applied for the detection of I− in drinking water and table salt samples.Graphical abstractImage 1
       
  • Nanoporous platinum electrode grown on anodic aluminum oxide membrane:
           Fabrication, characterization, electrocatalytic activity toward reactive
           oxygen and nitrogen species
    • Abstract: Publication date: Available online 30 June 2018Source: Analytica Chimica ActaAuthor(s): Wenyan Tao, Dawei Pan, Zanhua Gong, Xia Peng A new type of nanoelectrode, nanoporous platinum (NPt) electrode was prepared on aluminum oxide membrane by thermal evaporation deposition. The morphology, conductivity and electrocatalytic activity of NPt electrode were characterized and compared with those of nanofilm-Pt electrode through scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques, respectively. SEM images showed that “nanocavities” observed in NPt electrode were actually 2-dimensional enclosures by linked nanoparticles. It was different from the conventional arrays of “nanocavities” formed on homogeneous metal films. EIS data indicated that NPt electrode possesses higher conductivity. Compared with that on nanofilm-Pt electrode (14.05 Ω·cm2), the impedance spectrum on NPt electrode exhibits a semicircle portion with much smaller diameters (1.24 Ω·cm2 for NPt-100, 1.48 Ω·cm2 for NPt-200). Meanwhile, the response sensitivity of NPt electrode to O2 is 0.85 mA cm−2, which is larger than that of nanofilm-Pt electrode (0.54 mA cm−2). The largest catalytic current for nitric oxide (NO) was obtained in buffer with pH value of 9.4 while for Angeli's salt (AS) was obtained in buffer with pH value of 5.4. Additionally, electrocatalytic mechanisms of NPt electrode toward NO and AS were proposed, which indicating it depended on pH value of buffer solution.Graphical abstractThe nanoporous platinum electrode (NPt) prepared on anodic aluminum oxide membrane exhibited large specific area and good electrocatalytic activity to reactive oxygen (O2) and nitrogen species (NO and nitroxyl). Among them, the catalytic sensitivity of NPt electrode to O2 is up to 0.85 mA cm−2. The largest catalytic current for NO was obtained in pH 9.4 buffer while for nitroxyl was obtained in pH 5.4 buffer solution.Image 1
       
  • SPE-LC-MS investigations for the isolation and fractionation of acidic oil
           degradation products
    • Abstract: Publication date: Available online 29 June 2018Source: Analytica Chimica ActaAuthor(s): Dieter Schemeth, Nikoline Juul Nielsen, Jan H. Christensen In this study, we focus on isolation and fractionation strategies by solid phase extraction (SPE) for a broad range of environmentally related organic acids. These emerging potential contaminants are primary degradation products of spilled petrogenic compounds but little attention has been given to their environmental analysis and risk assessment. Three mixed-mode anion exchange sorbents possessing various backbone polarities were compared with respect to the extraction and fractionation efficiency. Quantitative analysis was obtained using an optimized and validated LC-MS method. We demonstrated the importance of reasonable ion source settings for highest sensitivity of individual carboxylic acids. Furthermore, fractionation of carboxylic acids into aliphatic and aromatic fractions by SPE was achieved by step-wise elution. Best performance regarding the isolation of low-concentration acids (sub μg L−1 level) in complex samples was attributed to Strata XA and is caused by high secondary hydrophobic interactions in addition to the ionic interactions. Isolation and fractionation of acid spiked diesel-spilled harbor water (22 μg L−1 spike level) revealed recoveries>80% for all tested carboxylic acids and low carry-overs of neutral petroleum compounds. We conclude that the isolation and fractionation of acidic degradation products by SPE is a powerful tool to investigate this new class of contaminants in relation to identification and ecological risk assessments.Graphical abstractImage 1
       
  • Kinetic study of continuous liquid-liquid extraction of wine with
           real-time detection
    • Abstract: Publication date: Available online 29 June 2018Source: Analytica Chimica ActaAuthor(s): Hui-Hsien Yang, Ewelina P. Dutkiewicz, Pawel L. Urban Kinetic optimization of continuous liquid-liquid extraction (CLLE) can shorten sample preparation times and reduce losses of labile or volatile analytes. Here, we coupled a downscaled CLLE apparatus with atmospheric pressure chemical ionization interface of triple quadrupole mass spectrometer. Real-time sampling was guided by an Arduino-based programmable logic controller. The recorded datasets were processed to compute the extraction rate constants for the target analytes. The extraction time in subsequent on-line experiments was set to 180 min as a compromise between the reduction of the analysis time and maximizing its yield. Interestingly, off-line analysis of the extract produced different results than on-line analysis pointing to the immanent degradation of the collected extract aliquots. Next, we implemented this hyphenated system in the analysis of red wine samples, which were stored during different periods of time after opening the bottle. The results reveal differences in the depletion of the volatile wine components during storage.Graphical abstractImage 1
       
  • One-step three-dimensional printing of enzyme/substrate–incorporated
           devices for glucose testing
    • Abstract: Publication date: Available online 29 June 2018Source: Analytica Chimica ActaAuthor(s): Cheng-Kuan Su, Jo-Chin Chen To substantially simplify the fabrication of analytical devices for rapid screening tests, in this study we employed multi-material fused deposition modeling-type three-dimensional printing (3DP) and two functionalized thermoplastic filaments—acrylonitrile butadiene styrene (ABS) incorporating peroxidase-mimicking iron oxide (Fe3O4) nanoparticles and polyvinyl alcohol (PVA) infiltrated with the chromogenic substrate o-phenylenediamine (OPD)—for the one-step manufacture of enzyme/substrate–incorporated multi-well plates. Upon contact with samples, these fabricated devices (i) released the chromogenic substrate OPD into the solution, (ii) efficiently catalyzed the oxidation of OPD mediated by the peroxidase substrate H2O2, (iii) enabled assays of those substances availably oxidized by their specific oxidases to generate H2O2, and (iv) facilitated colorimetric observation by the naked eye or through absorbance measurements after loading into a microplate reader. With glucose oxidase immobilized in each well, samples appropriately diluted could be directly loaded for derivatizing and analyzing glucose without adding any other reagents. After assay optimization, the limits of detection reached as low as 2.8 μM for H2O2 and 5.0 μM for glucose; the method's applicability was illustrated in terms of determining glucose concentrations in urine, serum, and plasma samples. These 3D-printed peroxidase mimic/chromogenic substrate–incorporated multi-well plates appear to be highly suitable for rapid and high-throughput screening of glucose in clinical samples. We demonstrate that adequate functionalization of raw materials for 3DP can contribute to the development of novel multifunctional devices with many potential practical applications.Graphical abstractImage 1
       
  • Past-in-the-Future. Peak detection improves targeted mass spectrometry
           imaging
    • Abstract: Publication date: Available online 28 June 2018Source: Analytica Chimica ActaAuthor(s): Francesca Falcetta, Lavinia Morosi, Paolo Ubezio, Silvia Giordano, Alessandra Decio, Raffaella Giavazzi, Roberta Frapolli, Mridula Prasad, Pietro Franceschi, Maurizio D'Incalci, Enrico Davoli Mass spectrometry imaging is a valuable tool for visualizing the localization of drugs in tissues, a critical issue especially in cancer pharmacology where treatment failure may depend on poor drug distribution within the tumours. Proper preprocessing procedures are mandatory to obtain quantitative data of drug distribution in tumours, even at low intensity, through reliable ion peak identification and integration. We propose a simple preprocessing and quantification pipeline. This pipeline was designed starting from classical peak integration methods, developed when “microcomputers” became available for chromatography, now applied to MSI. This pre-processing approach is based on a novel method using the fixed mass difference between the analyte and its 5 d derivatives to set up a mass range gate. We demonstrate the use of this pipeline for the evaluating the distribution of the anticancer drug paclitaxel in tumour sections. The procedure takes advantage of a simple peak analysis and allows to quantify the drug concentration in each pixel with a limit of detection below 0.1 pmol mm-2 or 10 μg g−1. Quantitative images of paclitaxel distribution in different tumour models were obtained and average paclitaxel concentrations were compared with HPLC measures in the same specimens, showing
       
  • Bifunctional aptasensor based on novel two-dimensional nanocomposite of
           MoS2 quantum dots and g-C3N4 nanosheets decorated with chitosan-stabilized
           Au nanoparticles for selectively detecting prostate specific antigen
    • Abstract: Publication date: Available online 27 June 2018Source: Analytica Chimica ActaAuthor(s): Fenghe Duan, Shuai Zhang, Longyu Yang, Zhihong Zhang, Linghao He, Minghua Wang A novel nanostructured biosensing platform was designed based on two-dimensional (2D) nanocomposite of graphitic carbon nitride (g-C3N4) nanosheets and MoS2 quantum dots (MoS2 QDs), followed by decoration with chitosan-stabilized Au nanoparticles (CS-AuNPs) (denoted as MoS2QDs@g-C3N4@CS-AuNPs), of which CS-AuNPs were prepared by plasma enhanced-chemical vapor deposition. Owning to the good surface plasmon performance of the CS-AuNPs and excellent electrochemical activity of MoS2QDs@g-C3N4 nanosheets, the as-obtained 2D MoS2QDs@g-C3N4@CS-AuNPs nanocomposite was simultaneously explored to construct both surface plasmon resonance spectroscopy (SPR) sensor and electrochemical aptasensor. The MoS2QDs@g-C3N4@CS-AuNPs-based aptasensor shows strong bio-binding affinity toward the prostate specific antigen (PSA) targeted aptamer strands as compared to the individual component, including MoS2 QDs, g-C3N4, and CS-AuNPs. When detecting PSA, the low limit of detection (LOD) of 0.71 pg mL−1 deduced by electrochemical aptasensor is three orders of magnitude lower than that deduced by SPR sensor (0.77 ng mL−1). As expected, both SPR sensor and electrochemical aptasensor demonstrate good selectivity, highly stability, acceptable reproducibility, and well consistent applicability in human serum. The satisfactory results suggest potential application of the MoS2QDs@g-C3N4@CS-AuNPs in bifunctional biosensing fields and clinical monitoring of cancer markers.Graphical abstractImage 1
       
  • Comparison of different speciation techniques to measure Zn availability
           in hydroponic media
    • Abstract: Publication date: Available online 27 June 2018Source: Analytica Chimica ActaAuthor(s): Encarna Companys, Josep Galceran, Jaume Puy, Maria Sedó, Ruben Vera, Enriqueta Anticó, Clàudia Fontàs Four analytical techniques are compared: AGNES (Absence of Gradients and Nernstian Equilibrium Stripping), LASV (Anodic Stripping Voltammetry with Linear stripping), DGT (Diffusive Gradients in Thin films) and PIM (Polymer Inclusion Membranes). These techniques have been designed to provide the free ion concentration or a labile fraction, complementarily contributing to an integrated description of speciation and availability. Their simultaneous application to the determination of free Zn concentrations or labile fluxes in seven solutions of a hydroponic medium reveals characteristics of each technique and correlations between their results. All dynamic results can be interpreted in terms of a general theoretical framework on fluxes. Indeed, in techniques under diffusion-limited conditions in the sample, the flux can be split into the free contribution (linearly proportional to the free fraction), plus the contribution of the complexes (where mobility, lability and abundance of complexation are intertwined). A methodology to compute lability degrees is developed. Measurements with PIM devices confirm that diffusion in the sample solution is not rate limiting, so its flux is proportional to the free metal in the donor solution. A proportionality between the responses of any given two techniques is observed, which suggests that, for the low ligand-to-metal concentration ratios used in the present work, any of these techniques would correlate similarly with uptake, toxic or nutritional measurements.Graphical abstractImage 1
       
  • Characterization of secondary metabolites from green cocoa beans using
           focusing-modulated comprehensive two-dimensional liquid chromatography
           coupled to tandem mass spectrometry
    • Abstract: Publication date: Available online 27 June 2018Source: Analytica Chimica ActaAuthor(s): Said Toro-Uribe, Lidia Montero, Luis López-Giraldo, Elena Ibáñez, Miguel Herrero Proanthocyanidins as well as other secondary metabolites present in green cocoa beans were studied thanks to a new method involving the use of on-line comprehensive two-dimensional liquid chromatography coupled to tandem mass spectrometry (LC × LC-MS/MS). In order to enhance the performance of previously developed methodologies, the use of different modulation strategies were explored. Focusing modulation clearly allowed the attainment of higher resolving power and peak capacity compared to non-focusing modulation set-ups. Moreover, the use of active modulation by the addition of a make-up flow efficiently helped to compensate for the solvent strength mismatch produced between dimensions. The optimized method was useful to successfully describe the secondary metabolite composition of green cocoa that was characterized by the presence of 30 main compounds, including 3 xanthines, 2 flavan-3-ols and 24 oligomeric procyanidins with a degree of polymerization up to 12. The obtained results showed that the proanthocyanidins found in the cocoa beans were exclusively B-type procyanidins. The existence of (epi)catechin subunits linked to sugar or galloyl moieties was not observed. The developed method produced a good separation of secondary metabolites allowing an improvement with respect to the available methodologies for the analysis of a complex food sample such as cocoa metabolites in terms of speed of analysis, resolution and peak capacity.Graphical abstractImage 1
       
  • Electro-addressable conductive alginate hydrogel for bacterial trapping
           and general toxicity determination
    • Abstract: Publication date: Available online 26 June 2018Source: Analytica Chimica ActaAuthor(s): N. Vigués, F. Pujol-Vila, A. Marquez-Maqueda, X. Muñoz-Berbel, J. Mas In biosensors development, alginate hydrogels are a first choice for enabling stable biomolecules entrapment in biocompatible membranes obtained under soft physiological conditions. Although widely exploited, most alginate membranes are isolating and poorly repetitive, which limit their application in biosensing. Significant steps forward on improving repeatability and conductivity have been performed, but to date there is no single protocol for controlled deposition of live cells in replicable conductive alginate layers. Here, cell electrotrapping in conductive alginate hydrogels is examined in order to overcome these limitations. Conductive alginate-coated electrodes are obtained after potentiostatic electrodeposition of graphite-doped alginate samples (up to 4% graphite). The presence of graphite reduces electrode passivation and improves the electrochemical response of the sensor, although still significantly lower than that recorded with the naked electrode. Bacterial electrotrapping in the conductive matrix is highly efficient (4.4 × 107 cells per gel) and repetitive (CV 
       
  • Harnessing the affinity of magnetic nanoparticles toward dye-labeled DNA
           and developing it as an universal aptasensor revealed by
           lipopolysaccharide detection
    • Abstract: Publication date: Available online 26 June 2018Source: Analytica Chimica ActaAuthor(s): Long Ma, Nana Sun, Yuanyuan Meng, Chunhao Tu, Xiuqi Cao, Yongchang Wei, Liqiang Chu, Aipo Diao In current study, we have found that several magnetic nanoparticles (MNPs) are able to absorb DNA molecules, and surface engineering would be beneficial to tune such interaction. We then have focused on the assembly of polyethylenimine (PEI) coated MNPs (PEI-MNPs) with ssDNA (single-stranded DNA) and found this assembly is mediated by two forces, namely the electrostatic interactions of surface charges of MNPs and the phosphate backbones of DNA; as well as the coordination of exterior iron ions (especially Fe3+) of MNPs and DNA phosphate backbones. The fluorescence of dye-labeled DNA is significantly quenched when being complexed with PEI-MNPs, which is proved to be caused by static quenching. This PEI-MNPs interact with DNA, which could be harnessed for devising a novel type of aptasensor. This has been examplified by the selective and sensitive detection of lipopolysaccharide (LPS). The LOD (limit of detection) is ∼35 ng/mL and the linear range from 50 ng/mL to 10 μg/mL. Compared with widely used graphene oxide (GO)‒ssDNA aptamer sensors, we also have demonstrated that the PEI-MNPs based sensor is able to better avoid non-specific DNA displacement by interfering proteins, generating more satisfactory signal-to-background ratio. Our proposed sensor could be a supplement to classic GO‒DNA sensors. In summary, our work provides fundamental understanding of MNPs‒DNA interactions and also paves the way for developing novel MNPs based sensing approaches, which would contribute to nano‒bio interface and DNA-assisted bio-analysis, DNA-coordinated nano-materials and DNA-directed assembly.Graphical abstractImage 1
       
  • Characterization of ion exchange functionalized cyclic olefin polymer open
           tubular columns
    • Abstract: Publication date: Available online 26 June 2018Source: Analytica Chimica ActaAuthor(s): Weixiong Huang, Sasikarn Seetasang, Purnendu K. Dasgupta We describe both the cation-exchange (CEX) and anion-exchange (AEX) capacity measurements of functionalized cyclic olefin polymer (COP) open tubular (OT) columns. COP capillaries were sulfonated to provide CEX functionality and then coated with AEX latex to provide AEX functionality. We measure functionalization uniformity along the column by (a) separately measuring capacities of two halves of a column, (b) measuring retention factors for several ions in successive 10 cm segments of a column in multiple injections and (c) measuring retention variance of a single ion in different segments of a column from a single injection. Data were collected in both flow directions. Errors in CEX capacity determination arises primarily from uncertainties in titration end point location. AEX capacities are typically 10x higher, reducing the relative measurement error. In the AEX case, both titration end point location error and variations in column internal diameter contribute to the overall uncertainty. Although sulfonation of COP results in nonuniform CEX functionalization, AEX latex coating of this surface results in uniform AEX coverage. Frontal displacement chromatography (using both admittance and optical detection) and acid-base titrimetry were compared for capacity measurement. In a pooled standard deviation based t-test for the data on 8 columns, at the 95% confidence level, CEX capacity differed significantly between two halves of a column. But AEX capacity of AEX columns prepared by coating the same CEX columns with AEX latex did not.Graphical abstractImage 1
       
  • A cotton thread fluidic device with a wall-jet pencil-drawn paper based
           dual electrode detector
    • Abstract: Publication date: Available online 26 June 2018Source: Analytica Chimica ActaAuthor(s): Nicolò Dossi, Rosanna Toniolo, Fabio Terzi, Nicola Sdrigotti, Franco Tubaro, Gino Bontempelli A simple and sensitive device is presented based on the use of pencil-drawn paper based electrochemical detector placed at the end of a cotton thread fluidic channel in wall-jet configuration. This innovative and fast responding electroanalytical system can be adopted for both single and dual electrode electrochemical detection, this last achieved by applying two different potentials at two independent working electrodes drawn on the opposite faces of the paper based detector. Its performance was preliminarily optimized by adopting hexacyanoferrate(II) as probe species undergoing reversible electrochemical processes. These devices were then used for the single electrode detection of ascorbic acid in aqueous samples and the dual electrode detection of orthodiphenols in extra virgin olive oils (EVOOs). In fact, these devices enable hydrophilic orthodiphenols, typically present in EVOOs (extracted by a 80:20% v/v acetonitrile/water mixture), to be discriminated from hydrophilic monophenols instead present in almost all vegetable oils. Flow-injections runs were conducted by using a 0.01 M H2SO4 + 0.5 KCl running electrolyte allowing the rapid and selective detection of hydrophilic orthodiphenols with satisfactory sensitivity and a low enough detection limit (2 μM). Different real samples of EVOOs and sunflower oils were analyzed. Abundant enough contents of orthidiphenols were found in EVOO samples, while no trace of these antioxidants was found in sunflower oils.Graphical abstractImage 1
       
  • A validated multi-matrix platform for metabolomic fingerprinting of human
           urine, feces and plasma using ultra-high performance liquid-chromatography
           coupled to hybrid orbitrap high-resolution mass spectrometry
    • Abstract: Publication date: Available online 26 June 2018Source: Analytica Chimica ActaAuthor(s): Ellen De Paepe, Lieven Van Meulebroek, Caroline Rombouts, Steve Huysman, Kaat Verplanken, Bruno Lapauw, Jella Wauters, Lieselot Y. Hemeryck, Lynn Vanhaecke In recent years, metabolomics has surfaced as an innovative research strategy in human metabolism, whereby selection of the biological matrix and its inherent metabolome is of crucial importance. However, focusing on a single matrix may imply that relevant molecules of complementary physiological pathways, covered by other matrices, are missed. To address this problem, this study presents a unique multi-matrix platform for polar metabolic fingerprinting of feces, plasma and urine, applying ultra-high performance liquid-chromatography coupled to hybrid quadrupole-Orbitrap high-resolution mass spectrometry, that is able to achieve a significantly higher coverage of the system's metabolome and reveal more significant results and interesting correlations in comparison with single-matrix analyses. All three fingerprinting approaches were proven ‘fit-for-purpose’ through extensive validation in which a number of endogenous metabolites were measured in representative quality control samples. For targeted and untargeted validation of all three matrices, excellent linearity (coefficients of determination R2 ≥ 0.99 or 0.90 respectively), recovery and precision (coefficients of variance ≤ 15% or 30% respectively) were observed. The potential of the platform was demonstrated by subjecting fecal, urine and plasma samples (collected within one day) from ten healthy volunteers to metabolic fingerprinting, yielding respectively 9 672, 9 647, and 6122 components. Orthogonal partial least-squares discriminant analysis provided similar results for feces and plasma to discriminate according to gender (p-value, R2X, R2Y and Q2Y), suggesting feces as an excellent alternative biofluid to plasma. Moreover, combining the different matrices improved the model's predictivity, indicating the superiority of multi-matrix platforms for research purposes in biomarker detection or pathway elucidation and in the selection of the most optimal matrix for future clinical purposes.Graphical abstractImage 1
       
  • Infrared laser ablation sampling coupled with data independent high
           resolution UPLC-IM-MS/MS for tissue analysis
    • Abstract: Publication date: Available online 26 June 2018Source: Analytica Chimica ActaAuthor(s): Michael E. Pettit, Fabrizio Donnarumma, Kermit K. Murray, Touradj Solouki Infrared laser ablation microsampling was used with data-dependent acquisition (DDA) and ion mobility-enhanced data-independent acquisition (HDMSE) for mass spectrometry based bottom-up proteomics analysis of rat brain tissue. Results from HDMSE and DDA analyses of the 12 laser ablation sampled tissue sections showed that HDMSE consistently identified approximately seven times more peptides and four times more proteins than DDA. To evaluate the impact of ultra-performance liquid chromatography (UPLC) peak congestion on HDMSE and DDA analysis, whole tissue digests from rat brain were analyzed at six different UPLC separation times. Analogous to results from laser ablated samples, HDMSE analyses of whole tissue digests yielded about four times more proteins identified than DDA for all six UPLC separation times.Graphical abstractImage 1
       
  • A novel diagnostic in situ derivatization kit for the simultaneous
           determination of 14 biomarkers of exposure to benzene, toluene, ethyl
           benzene and xylenes in human urine by isotope dilution liquid
           chromatography tandem mass spectrometry and kit optimization using
           response surface methodology
    • Abstract: Publication date: Available online 26 June 2018Source: Analytica Chimica ActaAuthor(s): Yehia Z. Baghdady, Kevin A. Schug Metabolite profiling can be used as a diagnostic measure for both short and long term co-exposure by individuals to benzene, toluene, ethylbenzene and xylenes (BTEX). A novel one pot derivatization in situ kit (OPDISK) was developed and optimized using a multivariate approach based on central composite design. The OPDISK was designed to simultaneously derivatize, in a urine sample matrix, a series of fourteen carboxylic acid and phenol-bearing urinary metabolites of BTEX to enhance their chromatographic analysis and sensitivity for detection by liquid chromatography – electrospray ionization – tandem mass spectrometry (LC-ESI-MS/MS). Using the reagent kit, the less responsive functional units on the molecules were converted to permanently positively-charged functional units. The kit was composed of three components, 2-fluoro-1-methylpyridinium p-toluenesulfonate (FMP), 3-carbinol-1-methylpyridinium iodide (CMP) and triethylamine (TEA) as a basic catalyst and, only after diluting a urine sample 20 fold with acetonitrile, was applied under mild conditions of room temperature and short reaction time of 20 min. The derivatized biomarkers were then directly analyzed using isotope dilution LC-ESI-MS/MS. The method was sensitive (limit of detection on column ranged from 1.4 pg to 3.1 ng), accurate (mean accuracy from 85% to 114%), and precise (mean coefficient of variation from 1% to 14%). The method results indicated a good linearity (R2 ≥ 0.990) for all metabolites. ClinChek® urine control samples were used successfully to demonstrate the accuracy of the method.Graphical abstractImage 1
       
  • A novel strategy for rapid detection of bacteria in water by the
           combination of three-dimensional surface-enhanced Raman scattering (3D
           SERS) and laser induced breakdown spectroscopy (LIBS)
    • Abstract: Publication date: Available online 26 June 2018Source: Analytica Chimica ActaAuthor(s): Wenlong Liao, Qingyu Lin, Shichen Xie, Yi He, Yonghui Tian, Yixiang Duan In this study, a novel strategy based on the combination of 3D SERS and LIBS was developed for qualitative and quantitative detection of bacteria. SERS-active Ag nanoparticles (AgNPs) were prepared by an improved in situ synthesis method, and reproducible SERS spectra of bacteria were obtained by natural evaporation of a droplet of the in situ synthesized sample. Four types of bacteria were classified via principal component analysis (PCA) and hierarchy cluster analysis (HCA). LIBS acted as a quantitative technique for bacterial detection based on the intracellular mineral cations, and bacteria could be detected in a linear range of 5 × 103–5 × 107 CFU mL−1, with recovery values ranging from 81.0% to 101.7%. The whole detection process including sample preparation and detection could be completed in approximately 30 min. With short assay time and simple operation, the proposed strategy has showed great potential for bacterial analysis.Graphical abstractImage 1
       
  • A novel HPLC flow cell integrated UV light emitting diode induced
           fluorescence detector as alternative for sensitive determination of
           aflatoxins
    • Abstract: Publication date: Available online 23 June 2018Source: Analytica Chimica ActaAuthor(s): Xuhui Geng, Nan Wang, Yan Gao, Haijing Ning, Yafeng Guan A novel UV light emitting diode induced fluorescence detector (LED-IF) with HPLC flow cell was designed and evaluated for determination of aflatoxins. Ray tracing method was employed to optimize the design of the optical components (such as reshaping thin lens for light source and fluorescence collection), and optical structure, and the geometry of flow cell. An ordinary UV LED with wavelength of 370 nm and radiant power of 5 mW was used as excitation light source. A photoelectric amplifier AccuOpt2000 with light sensitivity of 10−5∼10−4lx was utilized for fluorescence detection, instead of a photo multiplier tube (PMT). The lowest detection limit (LOD) of the LED-IF was 0.077 ppb for aflatoxin B1 by HPLC method without derivatization. The LED-IF was then coupled with a homemade iodine derivatization device, which was connected to the HPLC column outlet for determination of aflatoxins in edible oil and peanut samples. It was found that the edible oil sample contained aflatoxin B1 and B2 at average level of 7.14 (n = 3) and 0.30 ng/g (n = 3), respectively; while the peanut sample contained aflatoxin B1 and B2 at average level of 9.22 (n = 3) and 1.36 ng/g (n = 3), respectively. The overall power consumption of the LED-IF was 1 W/12 V. The sensitivity of the LED-IF was similar to commercial fluorescence detectors, which utilized a pulse Xe lamp as excitation light source and a PMT for detection, with power consumption of 150 W.Graphical abstractImage 1
       
  • A novel one- and two-photon fluorescent probe induced by light for
           selective imaging of Cys in living cells and tissues
    • Abstract: Publication date: Available online 22 June 2018Source: Analytica Chimica ActaAuthor(s): Yuxiang Ma, Ying Zhao, Lili Xia, Jinxin Huang, Yueqing Gu, Peng Wang A novel one- and two-photon fluorescent probe based on a photoreaction was developed for the detection of cysteine (Cys). After it was reacted with Cys and illuminated by light, a strong turn-on fluorescence was observed at the excitation of 390 nm. The probe IC-2 was well tolerated at physiological pH conditions and exhibited a fast response rate to Cys within 10 min. Moreover, the probe IC-2 displayed high selectivity towards Cys among other amino acids and metal ions. Fluorescence response studies suggested that the limit of detection of IC-2 was calculated as 2.6 × 10−8 M. An MTT assay demonstrated that IC-2 had good cell permeability and low cytotoxicity to HepG2 cells. Notably, IC-2 was successfully applied in one- and two-photon fluorescence imaging for Cys in living cells and tissues.Graphical abstractImage 1
       
  • PTR-MS and GC-MS as complementary techniques for analysis of volatiles: A
           tutorial review
    • Abstract: Publication date: Available online 21 June 2018Source: Analytica Chimica ActaAuthor(s): Tomasz Majchrzak, Wojciech Wojnowski, Martyna Lubinska-Szczygeł, Anna Różańska, Jacek Namieśnik, Tomasz Dymerski This tutorial review is a critical commentary on the combined use of two instrumental analytical techniques, namely GC-MS and PTR-MS. The first mention of such an analytical approach likely appeared after the year 2000 and despite many advantages, it has not been applied very often. Therefore, the aim of this article is to elaborate on the concept of their combined use and to provide a curse tutorial for those considering taking such an approach. The issue of complementarity was raised in a broad sense of this term. Special emphasis was placed on indicating the possibilities of complementary utilization of GC-MS and PTR-MS and presenting the advantages and disadvantages as well as the current application of these techniques when used together.Graphical abstractImage 1
       
  • Highly-sensitive voltammetric detection of trinitrotoluene on reduced
           graphene oxide/carbon nanotube nanocomposite sensor
    • Abstract: Publication date: Available online 21 June 2018Source: Analytica Chimica ActaAuthor(s): Sílvia V.F. Castro, Murilo N.T. Silva, Thiago F. Tormin, Mário H.P. Santana, Edson Nossol, Eduardo M. Richter, Rodrigo A.A. Munoz This work presents the highly-sensitive detection of 2,4,6-trinitrotoluene (TNT) on reduced graphene oxide/multi-walled carbon nanotube (rGO/MWCNT) nanocomposite sensor. The formation of a thin film of this nanocomposite occurred at the cyclohexane/water immiscible interface of a mixture of MWCNT and rGO in the biphasic solution. The film was transferred to a boron-doped diamond (BDD) electrode for the square-wave voltammetric detection of TNT, which presented improved analytical characteristics in comparison with bare BDD and after modification with precursors. Electrochemical impedance spectroscopy also revealed the faster electron transfer for a redox probe on the nanocomposite modified surface. The synergistic properties of both carbon nanomaterials in the thin film modified surface resulted in a TNT sensor with a detection limit of 0.019 μmol L−1 within a wide linear range (0.5–1100 μmol L−1), with superior performance in comparison with other electrochemical sensors produced with carbon nanomaterials. This new material provides great promises for the highly-sensitive detection of other nitroaromatic explosives as well as other analytes. Moreover, the interfacial method enables the production of homogeneous and stable films on large coated areas as well as the large-scale production of electrochemical sensors.Graphical abstractImage 1
       
  • Synthesis and characterization of the thermally reduced graphene oxide in
           argon atmosphere, and its application to construct graphene paste
           electrode as a naptalam electrochemical sensor
    • Abstract: Publication date: Available online 21 June 2018Source: Analytica Chimica ActaAuthor(s): Mariola Brycht, Andrzej Leniart, Janez Zavašnik, Agnieszka Nosal–Wiercińska, Krzysztof Wasiński, Paulina Półrolniczak, Sławomira Skrzypek, Kurt Kalcher New insight into the preparation of sensitive carbon–based electrochemical electrode is provided by examining the properties of thermally reduced graphene oxide (TRGO). In this paper, TRGO was prepared by thermal reduction of graphene oxide (GO) in argon atmosphere, and characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and atomic force microscopy (AFM). Results showed that thermal reduction in argon was effective to remove oxygen-containing functional groups in GO, and graphene sheets were obtained. Furthermore, TRGO was used to prepare thermally reduced graphene oxide paste electrode (TRGOPE) which showed excellent conductivity and fast electron transfer kinetics confirmed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electrode was applied to determination of the pesticide naptalam (Nap) in square–wave voltammetric (SWV) mode. The corresponding current at approx. +1.0 V increased linearly with the Nap concentration within two linear dynamic ranges (LDR) of 0.1–1.0 μmol L−1 (LDR1) and 1.0–10.0 μmol L−1 (LDR2). The limits of detection (LOD) and quantification (LOQ) for Nap were calculated as 0.015 μmol L−1 and 0.051 μmol L−1, respectively. In comparison to the carbon paste electrode (CPE) the results showed that the TRGOPE possesses advantages in terms of linearity, sensitivity and detectability.Graphical abstractImage 1
       
  • l-cysteine+in+complex+biological+fluids+and+living+cells&rft.title=Analytica+Chimica+Acta&rft.issn=0003-2670&rft.date=&rft.volume=">Red emission nitrogen, boron, sulfur co-doped carbon dots for
           “on-off-on” fluorescent mode detection of Ag+ ions and l-cysteine in
           complex biological fluids and living cells
    • Abstract: Publication date: Available online 20 June 2018Source: Analytica Chimica ActaAuthor(s): Shan Huang, Erli Yang, Jiandong Yao, Yi Liu, Qi Xiao Herein, a simple and efficient fluorescent assay for Ag+ ions and l-cysteine (L-Cys) in complex biological fluids and living cells was first developed based on the fluorescent “on-off-on” mode of red emission nitrogen, boron, sulfur co-doped carbon dots (NBS-CDs). Red emission NBS-CDs were prepared via one-step hydrothermal synthesis by using 3-aminobenzeneboronic acid and 2,5-diaminobenzenesulfonic acid as precursors. Such NBS-CDs exhibited excellent optical properties and relatively high absolute fluorescent quantum yield compared with some reported NBS-CDs. Due to the strong quenching ability of Ag+ ions on the fluorescence of NBS-CDs, red emission NBS-CDs were used for the determination of Ag+ ions with high sensitivity and excellent selectivity. The fluorescence of NBS-CDs was recovered after the interaction between Ag+ ions and L-Cys, which realized the specific determination of L-Cys in human urine samples and human plasma samples. The established NBS-CDs-based fluorescent “on-off-on” sensor offered a relatively low detection limits of 0.35 μM for Ag+ ions and 0.045 μM for L-Cys based on three times signal-to-noise criteria. Notably, this strategy was applied for the visual detections of Ag+ ions and L-Cys in living human cancer cells (HeLa cells and MCF-7 cells). This method is simple, high sensitive, and excellent selectivity, which provided a new insight on the potential applications of NBS-CDs to develop the biosensor in clinical diagnosis and other biologically related areas.Graphical abstractImage 1
       
  • Simultaneous electrochemical sensing of warfarin and maycophenolic acid in
           biological samples
    • Abstract: Publication date: Available online 20 June 2018Source: Analytica Chimica ActaAuthor(s): Mohammad-Bagher Gholivand, Mohammad Solgi In this study, for the first time a rapid, selective and highly sensitive method was developed for simultaneous determination of warfarin and mycophenolic acid using carbon paste electrode modified by β-cyclodextrin/multi-walled carbon nanotubes/cobalt oxide nanoparticles (β-CD/MWCNTs/Co3O4NPs/CPE). The oxidation peaks of desired drugs was separated enough using the constructed electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were utilized for study the electrochemical response of the fabricated electrode and its surface modification was investigated by electrochemical impedance spectroscopy (EIS). Under optimal conditions, the adsorptive stripping voltammetric responses were linear in the concentration ranges 0.05–150 μM and 0.5–200 μM for WAR and MPA, respectively. The correlation coefficients were greater than 0.99. The limits of detection for WAR and MPA were 0.02 and 0.03 μM. The fabricated electrode was applied for the simultaneous determination of WAR and MPA in urine and human serum samples with satisfactory results.Graphical abstractImage 1
       
  • Functional preserving carbon dots-based fluorescent probe for mercury (II)
           ions sensing in herbal medicines via coordination and electron transfer
    • Abstract: Publication date: Available online 20 June 2018Source: Analytica Chimica ActaAuthor(s): Jia Hui He, Yun Ying Cheng, Tong Yang, Hong Yan Zou, Cheng Zhi Huang Mercury ions (Hg2+) are one of the compulsory items in the quality control of herbal medicines for its serious toxicity to human health. Highly selective and sensitive Hg2+ detection, especially in complex real samples, is still challenging. In this work, Fluorescent (FL) carbon dots (CDs) with a core-shell structures composed of the crystalline core of stacked sp2-hybridized carbon layers and the shell of functional groups on the periphery of carbon layers are facilely prepared through a one-step hydrothermal synthetic route. They can specifically interact with Hg2+ in aqueous medium to form aggregates, during which coordination of carboxyl functional groups on the surface of CDs with Hg2+ occurred, which facilitated electron transfer from the CDs to Hg2+. As a result, fluorescence of the CDs was quenched with a high efficiency, making the detection of Hg2+ highly sensitive with the limit of determination (LOD) of 2.2 nM (3σ). With that, detection of Hg2+ in the complex compound herbal medicines samples with highly reproducible results has been successfully realized by using the as-prepared CDs, showing that fluorescent CDs-based probe may have great potential in the quality controls of heavy metals for pharmaceutical analysis.Graphical abstractImage 1
       
  • Copper nanoclusters/polydopamine nanospheres based fluorescence aptasensor
           for protein kinase activity determination
    • Abstract: Publication date: Available online 20 June 2018Source: Analytica Chimica ActaAuthor(s): Mengke Wang, Shun Wang, Dandan Su, Xingguang Su A fluorescence aptasensor was constructed for protein kinase (PKA) activity detection by utilizing copper nanoclusters (CuNCs) and polydopamine nanospheres (PDANS). Through the π-π stacking interactions between adenosine triphosphate (ATP) aptamer and PDANS, the ATP aptamer modified CuNCs (apt-CuNCs) were absorbed onto PDANS surface, thus the fluorescence of apt-CuNCs were quenched through fluorescence resonance energy transfer (FRET) from apt-CuNCs to PDANS. In the presence of ATP, ATP specifically bound to aptamer, causing the dissociation of apt-CuNCs from PDANS surface and restoring the fluorescence of apt-CuNCs. However, PKA translated ATP into adenosine diphosphate (ADP), and ADP had no competence to combine with ATP aptamer, thus, apt-CuNCs were released and absorbed onto the PDANS surface to cause the fluorescence quenching of apt-CuNCs again. Therefore, PKA activity was conveniently detected via the fluorescence signal change. Under the optimal conditions, PKA activity was detected in the range of 0.05–4.5 U mL−1 with a detection limit of 0.021 U mL−1. Furthermore, the feasibility of the aptasensor for kinase inhibitor screening was explored via assessment of kinase inhibitor H-89 as one model. This aptasensor was also performed for PKA activity determination in HepG2 cell lysates with satisfactory results.Graphical abstractImage 1
       
  • Investigation of dried blood sampling with liquid chromatography tandem
           mass spectrometry to confirm human exposure to nerve agents
    • Abstract: Publication date: Available online 20 June 2018Source: Analytica Chimica ActaAuthor(s): Rebecca L. Shaner, Rebecca M. Coleman, Nicholas Schulze, Kelsey Platanitis, Ashli A. Brown, Craig Seymour, Pearl Kaplan, Jonas Perez, Elizabeth I. Hamelin, Rudolph C. Johnson A method was developed to detect and quantify organophosphate nerve agent (OPNA) metabolites in dried blood samples. Dried blood spots (DBS) and microsampling devices are alternatives to traditional blood draws, allowing for safe handling, extended stability, reduced shipping costs, and potential self-sampling. DBS and microsamplers were evaluated for precision, accuracy, sensitivity, matrix effects, and extraction recovery following collection of whole blood containing five OPNA metabolites. The metabolites of VX, Sarin (GB), Soman (GD), Cyclosarin (GF), and Russian VX (VR) were quantitated from 5.0 to 500 ng mL−1 with precision of ≤16% and accuracy between 93 and 108% for QC samples with controlled volumes. For unknown spot volumes, OPNA metabolite concentrations were normalized to total blood protein to improve interpretation of nerve agent exposures. This study provides data to support the use of DBS and microsamplers to collect critical exposure samples quickly, safely, and efficiently following large-scale chemical exposure events.Graphical abstractImage 1
       
 
 
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