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Publisher: Elsevier   (Total: 3160 journals)

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Showing 1 - 200 of 3160 Journals sorted alphabetically
Academic Pediatrics     Hybrid Journal   (Followers: 37, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 25, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 97, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 28, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 37, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 5)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 7)
Acta Astronautica     Hybrid Journal   (Followers: 429, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 28, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 2)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 10, SJR: 0.18, CiteScore: 1)
Acta Haematologica Polonica     Free   (Followers: 1, SJR: 0.128, CiteScore: 0)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 291, SJR: 3.263, CiteScore: 6)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.504, CiteScore: 1)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.542, CiteScore: 1)
Acta Oecologica     Hybrid Journal   (Followers: 12, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 1, SJR: 1.793, CiteScore: 6)
Acta Poética     Open Access   (Followers: 4, SJR: 0.101, CiteScore: 0)
Acta Psychologica     Hybrid Journal   (Followers: 27, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access   (Followers: 1)
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 7, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 8)
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: 17, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 9, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 11, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 23)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 175, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 12, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 16, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 28, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 10, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 11, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 24, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 14, SJR: 0.572, CiteScore: 2)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.61, CiteScore: 7)
Advances in Botanical Research     Full-text available via subscription   (Followers: 2, SJR: 0.686, CiteScore: 2)
Advances in Cancer Research     Full-text available via subscription   (Followers: 32, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 4)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 14)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 28, 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: 26, SJR: 1.562, CiteScore: 3)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 20, 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: 13)
Advances in Digestive Medicine     Open Access   (Followers: 11)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 7)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Ecological Research     Full-text available via subscription   (Followers: 43, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 29, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 8)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 49, 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: 61, SJR: 0.591, CiteScore: 2)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Genetics     Full-text available via subscription   (Followers: 20, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 10, 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: 24, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 12, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 23)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 36, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 18, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 11, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 7, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 23)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 4)
Advances in Oncobiology     Full-text available via subscription   (Followers: 2)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 17, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.174, CiteScore: 0)
Advances in Parasitology     Full-text available via subscription   (Followers: 5, SJR: 1.579, CiteScore: 4)
Advances in Pediatrics     Full-text available via subscription   (Followers: 25, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 12)
Advances in Pharmacology     Full-text available via subscription   (Followers: 16, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.574, CiteScore: 1)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.109, CiteScore: 1)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 10)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 66)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (Followers: 1, SJR: 0.263, CiteScore: 1)
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.101, CiteScore: 0)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 6)
Advances in Space Research     Full-text available via subscription   (Followers: 415, 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: 12, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 35, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 19)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 15)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 49, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 366, 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: 472, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 17, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 31, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 43, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 4)
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 58, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 6, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 12, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 11)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 2, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 11, SJR: 1.142, CiteScore: 4)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.504, CiteScore: 1)
Allergology Intl.     Open Access   (Followers: 5, SJR: 1.148, CiteScore: 2)
Alpha Omegan     Full-text available via subscription   (SJR: 3.521, CiteScore: 6)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 10, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 52, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 4, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 4, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 6)
American Heart J.     Hybrid Journal   (Followers: 57, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 62, 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: 11)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 13, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 34, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 29, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 35, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 48)
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: 233, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 66, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5, SJR: 0.265, CiteScore: 0)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.289, CiteScore: 1)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, CiteScore: 1)
American J. of Pathology     Hybrid Journal   (Followers: 29, 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: 39, SJR: 1.141, CiteScore: 2)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.767, CiteScore: 1)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 7)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 63, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 20, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription   (Followers: 1)
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: 44, SJR: 1.512, CiteScore: 5)
Analytica Chimica Acta : X     Open Access  
Analytical Biochemistry     Hybrid Journal   (Followers: 201, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 12, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 14)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 23, SJR: 0.683, CiteScore: 2)
Angiología     Full-text available via subscription   (SJR: 0.121, CiteScore: 0)
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1, SJR: 0.111, CiteScore: 0)
Animal Behaviour     Hybrid Journal   (Followers: 208, SJR: 1.58, CiteScore: 3)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 6, SJR: 0.937, CiteScore: 2)

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Similar Journals
Journal Cover
Analytica Chimica Acta
Journal Prestige (SJR): 1.512
Citation Impact (citeScore): 5
Number of Followers: 44  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0003-2670 - ISSN (Online) 1873-4324
Published by Elsevier Homepage  [3160 journals]
  • Ratiometric fluorescence monitoring of α-glucosidase activity based on
           oxidase-like property of MnO2 nanosheet and its application for inhibitor
    • Abstract: Publication date: Available online 21 May 2019Source: Analytica Chimica ActaAuthor(s): Menglan Shi, Yao Cen, Guanhong Xu, Fangdi Wei, Xiaoman Xu, Xia Cheng, Yuying Chai, Muhammad Sohail, Qin Hu In recent years, α-glucosidase (α-Glu) inhibitor has been widely used in clinic for diabetic and HIV therapy. Although different systems have been constructed for sensitive and selective detection of α-Glu and screening its inhibitor, the method based on ratiometric fluorescence for α-glucosidase inhibitor screening remains poorly investigated. Herein, we constructed a new MnO2 nanosheet (NS)-based ratiometric fluorescent sensor for α-glucosidase activity assay and its inhibitor screening. MnO2 NS as an oxidase-mimicking nanomaterial directly oxidized o-phenylenediamine (OPD) into 2,3-diaminophenazine (DAP) which had a strong fluorescence emission at 575 nm, whereas the fluorescence of Ag nanoclusters (NCs) at 450 nm was then quenched by the generated DAP through inner filter effect (IFE). When 2-O-α-D-glucopyranosyl-L-ascorbic acid (AAG) as α-Glu substrate and α-Glu were introduced into the above system, MnO2 NS would be reduced to Mn2+ and lose the oxidase-like property since ascorbic acids (AA) were released with the hydrolysis of AAG by α-Glu. Thus, DAP would not be produced and IFE was stopped accompanying with the fluorescence decrease of DAP and fluorescence increase of AgNCs. A ratiometric fluorescent α-Glu nanosensor was thus developed. The fluorescence intensity ratio of DAP to AgNCs linearly decreased with the increasing of α-Glu concentrations in the range of 0.2-8 U mL-1, and limit of detection was 0.03 U mL-1. This proposed sensing approach was also expanded to α-Glu inhibitor screening and showed excellent applicability. As a typical α-Glu inhibitor, acarbose was investigated with a low detection limit of 10-8 M. The constructed sensor platform was proven to be sensitive and selective as well as simple, label-free and low-cost, making it promising for the accurate diagnosis of relevant disease and discovery of potential drugs.Graphical abstractSchematic of a ratiometric fluorescence sensor for monitoring α-glucosidase (α-Glu) activity and its application for inhibitor screening based on oxidase-like property of MnO2 nanosheet.Image 1
  • A FRET ratiometric fluorescent probe for detection of Hg2+ based on an
           imidazo[1,2-a]pyridine-rhodamine system
    • Abstract: Publication date: Available online 21 May 2019Source: Analytica Chimica ActaAuthor(s): Yanzhong Li, Sijia Qi, Chengcai Xia, Yanhao Xu, Guiyun Duan, Yanqing Ge A novel imidazo[1,2-a]pyridine-rhodamine ratiometric fluorescent probe IP-Hg for Hg2+ based on a fluorescence resonance energy transfer mechanism has been developed. The probe has been proved to show high sensitivity and high selectivity toward Hg2+. Furthermore, it could be used for imaging Hg2+ in cells and in polluted water.Graphical abstractImage 1
  • Direct Coupling of Solid Phase Microextraction with Electrospray
           Ionization Mass Spectrometry: A Case Study for Detection of Ketamine in
    • Abstract: Publication date: Available online 21 May 2019Source: Analytica Chimica ActaAuthor(s): Bin Hu, Bo Zheng, Daniel Rickert, German Augusto Gómez-Ríos, Barbara Bojko, Janusz Pawliszyn, Zhong-Ping Yao Electrospray ionization mass spectrometry (ESI-MS) is a commonly used technique for analysis of various samples. Solid phase microextraction (SPME) is a simple and efficient technique that combines both sampling and sample preparation into one consolidated step, preconcentrating extracted analytes for ultra-sensitive analysis. Historically, SPME has been coupled with chromatography-based techniques for sample separation prior to analysis, however more recently, the chromatographic step has been omitted, with the SPME device directly coupled with the mass spectrometer. In this study, direct coupling of SPME with ESI-MS was developed, and extensively validated to quantitate ketamine from human urine, employing a practical experimental workflow and no extensive hardware modification to the equipment. Among the different fibers evaluated, SPME device coated with C18/benzenesulfonic acid particles was selected for the analysis due to its good selectivity and signal response. Different approaches, including desorption spray, dripping, desorption ESI and nano-ESI were attempted for elution and ionization of the analytes extracted using the SPME fibers. The results showed that the desorption spray and nano-ESI methods offered better signal response and signal duration than the others that were evaluated. The analytical performance of the SPME-nano-ESI-MS setup was excellent, including limit of detection (LOD) of 0.0465827 ng/mL, limit of quantitation (LOQ) of 0.1 ng/mL, linear range of 0.1-500.0 ng/mL (R2=0.9995) and recoveries of 90.8-109.4% with RSD 3.4-10.6% for three validation points at 4.0,40 and 400.0 ng/mL, far better than the performance of conventional methods. The results herein presented, demonstrated that the direct coupling of SPME fibers with ESI-MS-based systems allowed for the simple and ultra-sensitive determination of analytes from raw samples such as human urine.Graphical abstractImage 1
  • The Effect of Protein Expression on Cancer Cell Capture using the Human
           Transferrin Receptor (CD71) as an Affinity Ligand
    • Abstract: Publication date: Available online 20 May 2019Source: Analytica Chimica ActaAuthor(s): Veronica J. Lyons, Amanda Helms, Dimitri Pappas Cancer cell detection in liquid biopsies has been a widely studied application in many microfluidic devices. The use of a common antibody, such as the epithelial cell adhesion molecule (Anti-EpCAM) or other specific antibodies, has facilitated the detection and study of many cancers. However, the use of such antibodies requires a priori knowledge of the cancer source, and many cancer subtypes are missed in screening applications. There remains a need to study a wider range of cancers that maintain the streamlined antibody approach in cell affinity separations. The Human transferrin receptor (CD71) has recently been demonstrated as a cancer cell affinity target in blood samples. CD71 expression in blood cells is low, whereas proliferating cancer cells have a higher expression of the surface protein. CD71 expression is variable with cell cycle, which can impact cell separations. In this work, we investigated the effects of cell cycle and CD71 expression on cell capture metrics. Six cancer cell lines were isolated from blood via CD71 affinity capture, with a capture efficiency and purity that varied with CD71 expression. Despite variation in CD71 expression, the affinity was sufficient to isolate cancer cells spiked into blood; under optimal conditions, CD71-based capture resulted in capture purity> 80%. We conclude that CD71 affinity separations show potential as a biomarker for cancer studies without sacrificing sensitivity and selectivity, and that cancer cells can be isolated from liquid biopsies over a range of expression of the target protein.Graphical abstractImage 1
  • Early Sepsis Diagnosis via Protein and miRNA Biomarkers using a novel
           Point-of-Care Photonic Biosensor
    • Abstract: Publication date: Available online 20 May 2019Source: Analytica Chimica ActaAuthor(s): Nuria Fabri-Faja, Olalla Calvo-Lozano, Priyanka Dey, Roland A. Terborg, M. Carmen Estévez, Alexander Belushkin, Filiz Yesilköy, Luc Duempelmann, Hatice Altug, Valerio Pruneri, Laura M. Lechuga Sepsis is a condition characterized by a severe stage of blood-infection often leading to tissue damage, organ failure and finally death. Fast diagnosis and identification of the sepsis stage (sepsis, severe sepsis or septic shock) is critical for the patient´s evolution and could help in defining the most adequate treatment in order to reduce its mortality. The combined detection of several biomarkers in a timely, specific and simultaneous way could ensure a more accurate diagnosis. We have designed a new optical point-of-care (POC) device based on a phase-sensitive interferometric biosensor with a label-free microarray configuration for potential high-throughput evaluation of specific sepsis biomarkers. The sensor chip, which relies on the use of metallic nanostructures, provides versatility in terms of biofunctionalization, allowing the efficient immobilization of different kind of receptors such as antibodies or oligonucleotides. We have focused on two structurally different types of biomarkers: proteins, including C-reactive protein (CRP) and Interleukin 6 (IL6) and miRNAs, using miRNA-16 as an example. Limits of Detection (LoD) of 18 μg mL-1, 88 μg mL-1 and 1 μM (6 μg mL-1) have been respectively obtained for CRP, IL6 and miRNA-16 in individual assays, with high accuracy and reproducibility. The multiplexing capabilities have also been assessed with the simultaneous analysis of both protein biomarkers.Graphical abstractImage 1
  • Comprehensive new approaches for variable selection using ordered
           predictors selection
    • Abstract: Publication date: Available online 20 May 2019Source: Analytica Chimica ActaAuthor(s): Jussara V. Roque, Wilson Cardoso, Luiz A. Peternelli, Reinaldo F. Teófilo New strategies of ordered predictors selection (OPS) were developed in this work, making this method more versatile and expanding its worldwide use and applicability. OPS is a recognized method to select variables in multivariate regression and is used by analytical chemists and chemometrists. It shows high ability to improve the prediction of models after the selection of a few and important variables. At the core of OPS is sorting variables from informative vectors and systematically investigating the regression models to identify the most relevant set of variables by comparing the cross-validation parameters of the models. Nevertheless, the first version of the OPS method performs variable selection using only one informative vector at a time and is limited to just one variable selection run. Then, three new strategies were proposed. First, an automatic method was developed to perform variable selection using several informative vectors and their combinations. Second, the feedback OPS is presented, in this new strategy the pre-selected variables would return to a new selection. Last, a method to apply OPS in full array subdivisions called OPS intervals was established. Initially, the new strategies were applied in the six datasets used in the original OPS paper to compare the prediction performance with the new OPS algorithms. After that, twelve new datasets were used to test and compare the new OPS approaches with other variable selection methods, genetic algorithm (GA), the interval successive projections algorithm for PLS (iSPA), and recursive weighted partial least squares (rPLS). The new OPS approaches outperformed the first OPS version and the other variable selection methods. Results showed that in addition to greater predictive capacity, the accuracy in the selection of expected variables is highly superior with the new OPS approaches. Overall, the new OPS provided the best set of selected variables to build more predictive and interpretative regression models, proving to be efficient for variable selection in different types of datasets.Graphical abstractImage 1
  • Online reaction based single-step capillary electrophoresis-systematic
           evolution of ligands by exponential enrichment for ssDNA aptamers
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Chao Zhu, Linsen Li, Ge Yang, Senbiao Fang, Manjiao Liu, Murtaza Ghulam, Chenxu Hao, Yubao Chen, Feng Qu Capillary electrophoresis-systematic evolution of ligands by exponential enrichment (CE-SELEX) has proven to be an effective technique for aptamers selection. In this study, we present an online reaction based convenient single-step CE-SELEX (ssCE-SELEX) mode with human thrombin (H-Thr) as a model target. The selection progress was monitored through bulk Kd analysis, which showed more than a 1000-fold improvement over the initial library after two rounds of selection. Three selected candidate sequences presented high binding affinities against H-Thr with nanomolar (nM) Kd determined by nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM, 56.4–177.1 nM) and CE based non-linear fitting (CE-NLF, 98.2–199.7 nM). They also exhibited high specificities towards H-Thr compared with bovine thrombin, IgG, lysozyme, and lactoferrin. Meanwhile, the Kd results by isothermal titration calorimetry (ITC) confirmed the effective CE in measuring the aptamer affinity. In addition, three candidates were applied as aptasensors in the AuNPs based colorimetric assay, which showed visible color change and good linear relationships (R2 > 0.93) with H-Thr concentration. Furthermore, molecular dynamics (MD) simulation was performed to validate the binding of the three candidates with H-Thr by binding sites and binding free energy. The ssCE-SELEX method avoids off-line incubation, saves time and sample, and may provide a universal and convenient method for aptamers selection.Graphical abstractImage 1
  • Lab-on-nanopaper: An optical sensing bioplatform based on curcumin
           embedded in bacterial nanocellulose as an albumin assay kit
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Tina Naghdi, Hamed Golmohammadi, Maryam Vosough, Mojgan Atashi, Iman Saeedi, Mohammad Taghi Maghsoudi Herein, we introduce a nanopaper-based analytical device (NAD) or “lab-on-nanopaper” device for visual sensing of human serum albumin (HSA) in human blood serums, which relies on embedding of curcumin within transparent bacterial cellulose (BC) nanopaper. BC nanopaper is an appropriate candidate to be an excellent platform for the development of optical (bio)sensors due to having exceptional properties such as optical transparency, high flexibility, porosity, biodegradability, and printability. The hydrophilic test zones were created on the fabricated bioplatform through creating the hydrophobic walls via laser printing technology. The color changes of curcumin embedded in BC nanopaper (CEBC) due to the inhibitory effect of HSA on the curcumin degradation in alkaline solutions, which can be monitored visually (naked eye/Smartphone camera) or spectroscopically using a spectrophotometer, were linearly proportional to the HSA concentration in the range of 10–300 μM and 25–400 μM, respectively. The developed NAD/CEBC as a novel albumin assay kit was successfully utilized to the determination of HSA in human blood serum samples with satisfactory results. Building upon the fascinating features of BC nanopaper as a very promising bioplatform in optical (bio)sensing applications we are confident “lab-on-nanopaper” devices/NADs, which take the advantages of the nanopaper and also meet the ASSURED criteria, could be considered as a new generation of optical (bio)sensing platforms that are currently based on paper, glass or plastic substrates.Graphical abstractImage 1
  • Rapid synthesis of Au/Ag bimetallic nanoclusters with highly biochemical
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Huanhuan Sun, Taiping Qing, Xiaoxiao He, Jingfang Shangguan, Ruichen Jia, Hongchang Bu, Jin Huang, Kemin Wang Herein, we developed a simple and rapid strategy to synthesize gold/silver bimetallic nanoclusters (Au/Ag NCs) with highly biochemical stability by a one-pot route. The Au/Ag NCs were obtained via a chemical reduction procedure in alkaline aqueous solution at 75 °C within only 20 min by employing bovine serum albumin (BSA) as both ligand and reductant. The as-obtained Au/Ag NCs displayed bright orange fluorescence with an emission peak located at 570 nm and temperature-dependent fluorescence property, which were utilized as fluorescent thermometer directly. More intriguingly, the Au/Ag NCs were very stable against various pH values, ions, biothiols, H2O2, fetal bovine serum (FBS), RPMI 1640 medium and amino acids. Taking advantage of the excellent biochemical stability, a ratiometric fluorescence biosensor, fluorescein-5-isothiocyanate (FITC)-Au/Ag NCs, was constructed for pH sensing based on the incorporation of FITC into the Au/Ag NCs. Furthermore, the ratiometric pH sensor was also successfully applied on the model of HeLa cells.Graphical abstractIn this work, we have described a simple and rapid approach for fabricating a highly stable Au/Ag NCs with highly biochemical stability. The as-obtained Au/Ag NCs exhibit obvious orange fluorescence and temperature-dependent property, which were utilized as fluorescent thermometer. Given the excellent biochemical stability, a ratiometric biosensor was also designed for pH sensing by incorporating pH sensitive FITC dyes into Au/Ag NCs.Image 1
  • Fabrication of polyethyleneimine-functionalized reduced graphene
           oxide-hemin-bovine serum albumin (PEI-rGO-hemin-BSA) nanocomposites as
           peroxidase mimetics for the detection of multiple metabolites
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Xiaoyue Zhang, You Yu, Jinglin Shen, Wei Qi, Hua Wang The ultrasensitive bioassays are increasingly demanded for disease diagnosis and environmental monitoring. The combined unique natures of the components in nanocomposites have led to their wide applications in bioanalysis. In the current study, a simple strategy for preparing polyethyleneimine-functionalized reduced graphene oxide-hemin-bovine serum albumin (PEI-rGO-Hemin-BSA) nanocomposites as peroxidase mimetics was demonstrated. The developed nanocomposites of PEI-rGO-Hemin-BSA showed an excellent peroxidase-like activity. Importantly, through the glutaradelhyde crosslinking, PEI-rGO-Hemin-BSA could be further simply combined with various oxidases such as glucose oxidase, cholesterol oxidase, lactate oxidase and choline oxidase for the detection and quantitative measurement of multiple metabolites including glucose, cholesterol, l-lactate, and choline. The developed detection strategy, which is sensitive, convenient, low-costed, and in tiny sample consumption, could be expected wide applications in the disease diagnosis and management of metabolite disorders.Graphical abstractImage 1
  • Development and application of a LC-HRMS/MS method for analyzing
           antihypertensive drugs in oral fluid for monitoring drug adherence
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Lilian H.J. Richter, Cathy M. Jacobs, Felix Mahfoud, Ingrid Kindermann, Michael Böhm, Markus R. Meyer Nonadherence to antihypertensive drugs therapy is known to be a serious issue in hypertension treatment. Liquid chromatography (LC) coupled to mass spectrometry (MS) was shown to allow the assessment of such nonadherence in blood and urine sample. However, their sampling may represent a logistical challenge and are often not favored by the patients. We questioned whether oral fluid (OF) might be an easier accessible alternative matrix for adherence monitoring of cardiovascular drugs (CD). A qualitative method for adherence monitoring of 78 commonly prescribed cardiovascular drugs in OF using LC high-resolution MS (LC-HRMS/MS) was therefore developed, validated, and used to study the presence of antihypertensive medication in OF. Selectivity, ion suppression and enhancement due coeluting analytes, carry over, limits of detection (LOD), limits of identification (LOI), recovery (RE), matrix effects (ME), and process efficiency (PE) were investigated. For demonstrating applicability, over 50 OF samples were investigated and data were compared to findings in blood and urine. Selectivity in OF was given for all compounds via their MS2 spectra and no total suppression of signals could be observed. Determined LOI in OF for ten analytes was higher than the given therapeutic plasma concentration. Furthermore, RE, ME, and PE were in acceptable ranges for more than 65% of the compounds. In total, 208 prescriptions of CD to 57 patients were analyzed and demonstrated the suitability of for adherence monitoring in principle. OF was comparable to plasma regarding the drug categories and the frequencies of hits, except for acidic compounds but more hits could be found in urine samples. A analytical method using OF as analytical matrix was successfully developed. Application showed that it might be a suitable alternative for adherence monitoring of selected drugs in the future, particularly those having no acidic function.Graphical abstractUsing OF as analytical matrix was successfully evaluated showing that it might be a suitable alternative foradherence monitoring of most cardiovascular drugs.Image 1
  • Proteomics analysis of site-specific glycoforms by a virtual multistage
           mass spectrometry method
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Hongqiang Qin, Yao Chen, Jiawei Mao, Kai Cheng, Deguang Sun, Mingming Dong, Lu Wang, Liming Wang, Mingliang Ye Determination of site-specific glycoforms is the key to reveal the micro-heterogeneity of protein glycosylation at proteome level. Herein, we presented an integrated virtual multistage MS strategy to identify intact glycopeptides, which allowed the determination of site-specific glycoforms. In this strategy, the enzymatically de-glycosylated peptides and intact glycopeptides were mixed and analyzed in the same LC-MS/MS run. The acquired MS2 spectra of intact glycopeptides allowed determination of the glycans, and the MS2 spectra of the de-glycosylated peptides enabled the identification of peptide backbone sequences. Compared with the conventional multistage strategy, the peptide backbones could be directly identified by the MS2 of the de-glycopeptides with higher sensitivity. This strategy was first validated by analyzing the glycosites and site-specific glycoforms of mouse liver tissues. Then, it was applied to differential analysis of the glycoproteomes of hepatocellular carcinoma (HCC) and adjacent liver tissues. Compared with the identification scheme using only MS2 spectra of intact glycopeptides or glycosites, this approach enabled quantitative analysis on two levels, i.e. glycosites and site-specific glycoforms, simultaneously. Thus, it could be a powerful tool to characterize the subtle differences in the macro- and micro-heterogeneity of protein glycosylation for different samples.Graphical abstractA powerful tool to characterize the subtle differences in the micro-heterogeneity of protein glycosylation for different samples by using the virtual multistage mass spectrometry method.Image 1
  • Stable isotope labeling combined with liquid chromatography-tandem mass
           spectrometry for comprehensive analysis of short-chain fatty acids
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Jie Zheng, Shu-Jian Zheng, Wen-Jing Cai, Lei Yu, Bi-Feng Yuan, Yu-Qi Feng Short-chain fatty acids (SCFAs) are one class of bacterial metabolites mainly formed by gut microbiota from undigested fibers and proteins. These molecules are able to mediate signal conduction processes of cells, acting as G protein-coupled receptors (GPR) activators and histone deacetylases (HDAC) inhibitors. It was reported that SCFAs were closely associated with various human diseases. However, it is still challenging to analyze SCFAs because of their diverse structures and broad range of concentrations. In this study, we developed a highly sensitive method for simultaneous detection of 34 SCFAs by stable isotope labeling coupled with ultra-high performance liquid chromatography-electrospray ionization-mass spectrometry (UHPLC-ESI-MS/MS) analysis. In this respect, a pair of isotope labeling reagents, N-(4-(aminomethyl)benzyl)aniline (4-AMBA) and N-(4-(aminomethyl)benzyl)aniline-d5 (4-AMBA-d5), were synthesized to label SCFAs from the feces of mice and SCFA standards, respectively. The 4-AMBA-d5 labeled SCFAs were used as internal standards to compensate the ionization variances resulting from matrix effect and thus minimize quantitation deviation in MS detection. After 4-AMBA labeling, the retention of SCFAs on the reversed-phase column increased and the separation resolution of isomers were improved. In addition, the MS responses of most SCFAs were enhanced by up to three orders of magnitude compared to unlabeled SCFAs. The limits of detection (LODs) of SCFAs were as low as 0.005 ng/mL. Moreover, good linearity for 34 SCFAs was obtained with the coefficient of determination (R2) ranging from 0.9846 to 0.9999 and the intra- and inter-day relative standard deviations (RSDs) were
  • Simple fabrication of zirconium and nitrogen co-doped ordered mesoporous
           carbon for enhanced adsorption performance towards polar pollutants
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Chuyi Ni, Junlong Huang, Xintong Xie, Yueru Shi, Juan Zheng, Gangfeng Ouyang Ordered mesoporous carbons (OMCs) are a kind of remarkable adsorbents in environment area due to high surface area, controllable pore size and superior stability. However, the inherent hydrophobicity and strong π-π interaction make OMCs have an advantage for the adsorption of nonpolar pollutants, leading to great demands for the development of new-type OMCs with outstanding adsorption efficiencies towards polar pollutants. The zirconium and nitrogen co-doped ordered mesoporous carbon (Zr/N-OMC) was obtained by directly carbonizing the composites of phenolic resin and UiO-66-NH2, with uniform mesopore structure, large surface area (583 m2 g−1) and widely dispersed heteroatoms. Due to these prominent properties, the Zr/N-OMC was fabricated as high-performance solid phase microextraction coating. The results proved that the doping zirconium and nitrogen could act as active sites to interact with polar pollutants, resulting in fast adsorption rate and enhanced adsorption capacity. Therefore, the high-performance Zr/N-OMC-coated fiber was coupled with gas chromatography-mass spectrometry to establish sensitive analytical method for the detection of trace phenols from real water samples. This work would open up a new avenue for simple and efficient modification of OMC with enhanced adsorption performance to expand applications.
  • Targeting bioactive compounds in natural extracts - Development of a
           comprehensive workflow combining chemical and biological data
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Lucie Ory, El-Hassane Nazih, Sahar Daoud, Julia Mocquard, Mélanie Bourjot, Laure Margueritte, Marc-André Delsuc, Jean-Marie Bard, Yves François Pouchus, Samuel Bertrand, Catherine Roullier In natural product drug discovery, several strategies have emerged to highlight specifically bioactive compound(s) within complex mixtures (fractions or crude extracts) using metabolomics tools. In this area, a great deal of interest has raised among the scientific community on strategies to link chemical profiles and associated biological data, leading to the new field called “biochemometrics”. This article falls into this emerging research by proposing a complete workflow, which was divided into three major steps. The first one consists in the fractionation of the same extract using four different chromatographic stationary phases and appropriated elution conditions to obtain five fractions for each column. The second step corresponds to the acquisition of chemical profiles using HPLC-HRMS analysis, and the biological evaluation of each fraction. The last step evaluates the links between the relative abundances of molecules present in fractions (peak area) and the global bioactivity level observed for each fraction. To this purpose, an original bioinformatics script (encoded with R Studio software) using the combination of four statistical models (Spearman, F-PCA, PLS, PLS-DA) was here developed leading to the generation of a “Super list” of potential bioactive compounds together with a predictive score. This strategy was validated by its application on a marine-derived Penicillium chrysogenum extract exhibiting antiproliferative activity on breast cancer cells (MCF-7 cells). After the three steps of the workflow, one main compound was highlighted as responsible for the bioactivity and identified as ergosterol. Its antiproliferative activity was confirmed with an IC50 of 0.10 μM on MCF-7 cells. The script efficiency was further demonstrated by comparing the results obtained with a different recently described approach based on NMR profiling and by virtually modifying the data to evaluate the computational tool behaviour. This approach represents a new and efficient tool to tackle some of the bottlenecks in natural product drug discovery programs.Graphical abstractImage 1
  • QuEChERS - Fundamentals, relevant improvements, applications and future
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Rosa Perestrelo, Pedro Silva, Priscilla Porto-Figueira, Jorge A.M. Pereira, Catarina Silva, Sonia Medina, José S. Câmara The Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method is a simple and straightforward extraction technique involving an initial partitioning followed by an extract clean-up using dispersive solid-phase extraction (d-SPE). Originally, the QuEChERS approach was developed for recovering pesticide residues from fruits and vegetables, but rapidly gained popularity in the comprehensive isolation of analytes from different matrices. According to PubMed, since its development in 2003 up to November 2018, about 1360 papers have been published reporting QuEChERS as extraction method. Several papers have reported different improvements and modifications to the original QuEChERS protocol to ensure more efficient extractions of pH-dependent analytes and to minimize the degradation of labile analytes. This analytical approach shows several advantages over traditional extraction techniques, requiring low sample and solvent volumes, as well as less time for sample preparation. Furthermore, most of the published studies show that the QuEChERS protocol provides higher recovery rate and a better analytical performance than conventional extraction procedures.This review proposes an updated overview of the most recent developments and applications of QuEChERS beyond its original application to pesticides, mycotoxins, veterinary drugs and pharmaceuticals, forensic analysis, drugs of abuse and environmental contaminants. Their pros and cons will be discussed, considering the factors influencing the extraction efficiency. Whenever possible, the performance of the QuEChERS is compared to other extraction approaches. In addition to the evolution of this technique, changes and improvements to the original method are discussed.Graphical abstractImage 1
  • Outside Front Cover
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s):
  • Fast screening of antibiotics in milk using a molecularly imprinted
           two-dimensional photonic crystal hydrogel sensor
    • Abstract: Publication date: 6 September 2019Source: Analytica Chimica Acta, Volume 1070Author(s): Yifei Wang, Tengsheng Xie, Ji Yang, Meng Lei, Jing Fan, Zihui Meng, Min Xue, Lili Qiu, Fenglian Qi, Zhe Wang As a typical antibiotic that is harmful to the health of human beings and widely used in animal husbandry, oxytetracycline (OTC) has a potential threat to the food safety. Therefore, the design of portable sensors for efficiently monitoring trace amounts of OTC in foods is vital to maintain safe food supply in our daily life. Herein, a two-dimensional (2D) molecularly imprinted photonic crystal hydrogel (MIPCH) sensor for the detection of OTC was fabricated by combining the photonic crystal (PC) method and molecular imprinting technique. In this regard, OTC was used as imprinted template to form the MIPCH sensor with specific binding sites during polymerization. After the removal of template, the obtained MIPCH possessed the specific nanocavities that were complementary to target compound, OTC. In addition, the response of the MIPCH to tetracyclines (TCs) in aqueous solution was monitored through a readable change of Debye diffraction ring, which is related to the particle spacing variation of MIPCH in response to the target molecules. As the concentration of OTC increased from 0 to 60 μM, the particle spacing of MIPCH sensor increased to about 94 nm and the structural color redshifted from blue to red. More importantly, the detection of OTC in milk sample by this portable, cost-effective MIPCH sensor has also been achieved at the same range of OTC. With the increasing concentration of OTC in milk sample, the particle spacing of MIPCH sensor increased about 92 nm and the structural color of MIPCH changed from blue through green to orange.Graphical abstractImage 1
  • Polyphenol-Hydrogen Peroxide Reactions in Skin: In vitro Model Relevant to
           Study ROS Reactions at Inflammation
    • Abstract: Publication date: Available online 18 May 2019Source: Analytica Chimica ActaAuthor(s): Mahboubeh Eskandari, Jadwiga Rembiesa, Lauryna Startaitė, Anna Holefors, Audronė Valančiūtė, Farnoush Faridbod, Mohammad Reza Ganjali, Johan Engblom, Tautgirdas Ruzgas Antioxidants are important to protect and maintain biological barriers, such as the skin. Antioxidant effects are often assessed using clinical trials, however these tests are costly and time consuming. In this work we introduce a skin membrane-covered oxygen electrode (SCOE) as an in vitro tool for monitoring H2O2 and antioxidant reactions in skin. The SCOE gives amperometric response to H2O2 concentrations down to 0.05 mM. More importantly, the electrode allows measurements of polyphenol penetration and reaction with H2O2 in skin. Measurements with SCOE show that lipophilic polyphenols such as quercetin, piceatannol, resveratrol, and plant extract from Plantago major impose their antioxidant effect in skin within 2-20 min. Rutin is however too hydrophilic to penetrate into stratum corneum and therefore cannot deliver its antioxidant effect during similar time interval. The measurements are interpreted considering polyphenol partition-penetration through stratum corneum and the reaction with the H2O2-catalase system in the skin. The contribution of other enzymes cannot be ruled out and will be addressed in the future.Graphical abstractImage 1
  • Simplification of organic matter before voltammetric determination of
           Tl(I) and Tl(III) in water using nanostructured photocatalyst and solar
    • Abstract: Publication date: Available online 17 May 2019Source: Analytica Chimica ActaAuthor(s): Ewa Biaduń, Krzysztof Miecznikowski, Monika Sadowska, Alicja Kużelewska, Krzysztof Drwal, Beata Krasnodębska-Ostręga The crucial point of this study was to verify the hypothesis that both thallium species are not affected by the procedure of photolysis when it is applied as a method of simplification of sample matrix containing surfactants, and that this method of sample pretreatment leads to reliable results of Tl speciation analysis. It is important especially because of high instability of Tl(III), which makes partial reduction of Tl(III)DTPA complex unavoidable. After conservation of Tl speciation by addition of DTPA the photolysis assisted with nanostructured hierarchically organized film was performed using “solar lamp” (Fe2O3/WO3/Fe2O3 film, pH 6, 380-800 nm). The results imply that under proposed photolysis conditions Tl(I) is not oxidized in the presence of water matrix, SDS nor DTPA. Also, even 100-fold excess of Fe(III) ions over Tl(I) ions does not accelerate the oxidation of Tl(I) to Tl(III), and already 2 hours of heterogeneous photolysis allow to limit the interferences caused by SDS and obtain reliable results. The data obtained by anodic stripping voltammetry (ASV) were verified using an inter-method comparison with SEC ICP MS. Moreover, after 2 h irradiation the reduction rate of Tl(III)DTPA standard solution increased only slightly from 2-3% to 4-6%. The presence of river water matrix causes a slightly higher (9%) reduction of the trivalent form. These changes are irrelevant in the context of instability of Tl(III) compounds. This study indicates that “soft decomposition” can be applied in speciation analysis of thallium in water matrix.Graphical abstractImage 1
  • Electrochemical aptamer-based microsensor for real-time monitoring of
           adenosine in vivo
    • Abstract: Publication date: Available online 17 May 2019Source: Analytica Chimica ActaAuthor(s): Di Zhang, Jiajia Ma, Xiangwen Meng, Zhifang Xu, JianZhang, Yuxin Fang, Yi Guo In this work, an implantable and minimally invasive micro-aptasensor for adenosine monitoring in vivo, based on flexible integrated electrodes, was developed. Firstly the sensor was made by the modification of a needle-type electrode with reduced graphene oxide and gold nanoclusters (rGO-AuNCs) using two-step electrodeposition. Secondly Sulfhydryl-terminated capture probe (ssDNA1) was immobilized on rGO-AuNCs modified electrode surface by self-assembly, and then it was hybridized with adenosine aptamer (ssDNA2). Lastly methylene blue (MB) as an electrochemical indicator was adsorbed on the aptamer through specific interaction of MB with guanine base. The peak current of MB decreased linearly with increasing adenosine concentration due to the formation of aptamer-adenosine complex and displacement of the aptamer from the modified electrode surface. The sensor showed a low detection limit of 0.1 nM with signal-to-noise ratio equal to 3 as well as a wide linear response range (0.1 nM-1 mM) in vitro. Also, a high selectivity was demonstrated for adenosine in relation to uridine, guanosine, and cytidine. Experiments in vivo demonstrated fast responses for a range of adenosine concentrations. This work demonstrates a promising path for implantable devices for the determination of biomolecules in vivo, thus allowing for health tests, detection of infectious diseases, and other medical conditions.
  • Proximity ligation assays for precise quantification of femtomolar
           proteins in single cells using self-priming microfluidic dPCR chip
    • Abstract: Publication date: Available online 17 May 2019Source: Analytica Chimica ActaAuthor(s): Jiumei Hu, Tong Gou, Wenshuai Wu, Jingjing Sun, Shan Zhang, Shufang Zhou, Juxin Yin, Ying Mu The quantification of low concentration proteins can facilitate the discovery of some significant biomarkers, and provide us a more profound understanding of cell heterogeneity when applied to single cell analysis. However, most state-of- art single cell protein detection platforms are bulky, expensive and complicated. Here we report a simple and low cost microfluidic dPCR (digital polymerase chain reaction) chip-based proximity ligation assay (PLA) for the quantification of low concentration proteins. First, standard hCSTB (human cystatin B) protein was used to optimize the related experimental conditions. Comparing to ordinary PLA tests, the results showed that our method achieved femtomolar limit of detection (LOD) with a linear dynamic range over three to four orders of magnitude. Then human CD147 protein, a reported biomarker for hepatoma carcinoma, was detected in single HepG2 and L02 cells. The results showed that there were wide disparities in single cell CD147 abundance for both of the two cell lines. And the average CD147 protein content in single HepG2 cells displayed 2-fold increase in comparison to that in single L02 cells. Comparing to the research findings obtained at bulk level, our method can provide more useful information for diagnosis and targeted therapy of tumors.Graphical abstractImage 1
  • Effects of pendant-like hydrophilic monomers on the adsorption properties
           of reversed-phase-type sorbents for solid-phase extraction
    • Abstract: Publication date: Available online 17 May 2019Source: Analytica Chimica ActaAuthor(s): Hiroya Murakami, Hiroki Tomita, Takuya Aoyanagi, Takashi Sugita, Yuta Miki, Yukihiro Esaka, Yoshinori Inoue, Norio Teshima Solid-phase extraction (SPE) has been extensively employed as a pretreatment method. In SPE, reversed-phase-type sorbents have been widely applied for the pretreatment of environmental or biological samples. Hydrophilic–lipophilic balance (HLB)-type sorbents, constituting the copolymers used as reversed-phase-type sorbents, have been applied for various sample pretreatment methods. In HLB-type sorbents, the hydrophilic monomer contributes to the improved wettability of sorbents and increase of polar interactions. In this study, three pendant-like hydrophilic monomers, viz. N-vinylpyrrolidone (NVP), 4-acryloylmorpholine (AMO), and 4-vinyl-1,3-dioxolan-2-one (VDO), respectively, exhibiting different Log P values and possibly causing different polar interactions, were selected to improve the adsorption properties of polar compounds, and divinylbenzene (DVB)-based HLB-type sorbents containing each hydrophilic monomer were synthesized and examined. By the optimization of the molar ratio of DVB and the hydrophilic monomer (i.e. HLB), the inert diluent, and the degree of cross-linking, the developed sorbents exhibited higher recoveries for various polar compounds (viz. cytosine, uracil, cytidine, uridine, 2′-deoxycytidine, 2′-deoxyguanosine, adenine, thymidine, adenosine, and 2′-deoxyadenosine) compared to commercially available HLB-type sorbents.
  • A novel electrochemical sensor based on 2D CuTCPP nanosheets and platelet
           ordered mesoporous carbon composites for hydroxylamine and chlorogenic
    • Abstract: Publication date: Available online 16 May 2019Source: Analytica Chimica ActaAuthor(s): Xin Zhao, Jing Bai, Xiangjie Bo, Liping Guo In this work, porphyrin-based 2D MOF CuTCPP/platelet ordered mesoporous carbon (pOMC) composites were successfully synthesized by conventional solvothermal reaction. The introduction of pOMC increases conductivity of CuTCPP/pOMC composites, weakens accumulation of the CuTCPP layers, and exposes active sites of CuTCPP. CuTCPP/pOMC composites show high electro-catalytic activity to the oxidation of hydroxylamine and the redox of chlorogenic acid. An electrochemical sensor based on CuTCPP/pOMC was constructed for quantitative determination of hydroxylamine and chlorogenic acid, and relevant mechanisms were discussed. Under optimized conditions, the fabricated sensor displays two wide linear responses in the ranges of 5.8 - 733.8 μM and 733.8 - 2933.8 μM for hydroxylamine, with a rapid response time about 1 s. For chlorogenic acid, the sensor presents linear responses in the ranges of 0.1 - 2 μM and 2 - 15 μM, with a high sensitivity of 10.18 μA/μM. The sensor was used to detect hydroxylamine and chlorogenic acid in real samples, and satisfactory results were obtained. The synthesis of CuTCPP/pOMC composites provides new strategy for designing electrochemical sensors based on 2D MOFs.Graphical abstractImage 1
  • Hairpin/DNA ring ternary probes for highly sensitive detection and
           selective discrimination of microRNA among family members
    • Abstract: Publication date: Available online 16 May 2019Source: Analytica Chimica ActaAuthor(s): Xiaoxia Liu, Mengqi Zou, Daxiu Li, Ruo Yuan, Yun Xiang The detection and quantification of microRNA (miRNA) plays essential roles in clinical and biomedical research. Yet, it is of major challenge to sense miRNA with high degree of selectivity and sensitivity due to its unique characteristics of short length, similarity of sequence among family members and low abundance. Here, with the design of a new hairpin/DNA ring ternary probe, we describe the development of a rolling circle amplification (RCA) method for sensitively and selectively sensing miRNA from cancer cells. The target miRNA binds the hairpin/DNA ring probes through toehold-mediated strand displacement (TSD) to form the ternary structures, in which the bound miRNA and DNA ring are respectively used as the primer and template to realize RCA, leading to the generation of many repeated metal ion-dependent DNAzyme sequences. The fluorescently quenched hairpin signal probes can be cyclically cleaved by these DNAzyme sequences with co-existence of the corresponding metal ions in buffer to show drastically enhanced fluorescence recovery for highly sensitive sensing of miRNA in the range between 10 fM and 10 nM with a detection limit of 1.51 fM. Besides, owing to the high base variation discrimination ability of TSD, selective detection of the target miRNA among the corresponding family members can be achieved by this method. Moreover, such a method can also be employed to differentiate miRNA expression variations in cancer cells for screening potential therapeutic drugs.Graphical abstractImage 1
  • On-Site Cell Concentration and Viability Detections using Smartphone based
           Field-Portable Cell Counter
    • Abstract: Publication date: Available online 16 May 2019Source: Analytica Chimica ActaAuthor(s): Wenjie Kang, Huachuan Huang, Ming Cai, Yangyang Li, Wei Hou, Feng Yun, Xuping Wu, Liang Xue, Shouyu Wang, Fei Liu We designed a smartphone based field-portable cell counter combining the smartphone microscope for bright-field image recording and the smartphone application for automatically cell recognition, counting and analysis. To our best knowledge, it is the first time that a smartphone based cell counter can distinguish and count both live and dead cells simultaneously. Compared to the results obtained by hemocytometer, commercial cell counter and flow cytometer, the proposed device was proved to detect cell concentration and viability accurately within the application range between 105 cells/mL and 107 cells/mL. Though multiple fields of view were measured to increase the sampling amount for error reduction, the whole operations including image recording and processing can still be finished rapidly. Moreover, the proposed device is cost-effective with small size of 170 mm × 113 mm × 168 mm containing a built-in power supply. Considering its advantages as high accuracy, fast speed, low cost, long battery life and compact configuration, it is believed the proposed device is a potential tool applied in on-site cell analysis.Graphical abstractImage 1
  • Eliminating the secondary structure of targeting strands for enhancement
           of DNA probe based low-abundance point mutation detection
    • Abstract: Publication date: Available online 16 May 2019Source: Analytica Chimica ActaAuthor(s): Zhihao Ming, Qianzhi Chen, Na Chen, Meng Lin, Na Liu, Junbo Hu, Xianjin Xiao Nucleic acid probes are very useful tools in biological and medical science. However, the essential sensing mechanism of nucleic acid probes was prone to the interference of surrounding sequences. Especially when the target sequences formed secondary structures such as hairpin or quadruplex, the nucleic acid probes were hindered from hybridizing with target strands, greatly disabled the function of probes. Herein, we have established an Open strand based strategy for eliminating the influence of secondary structures on the performance of nucleic acid probes. The strategy was general toward different lengths, secondary structures and sequences of the targeting strand, and we found that the improvement was higher when the secondary structure of the targeting strand was more complicated. Experiments on synthetic single stranded DNA and real clinical genomic DNA samples were conducted for low abundance mutation detection, and the limit of detection for TERT-C228T and BRCA2 rs80359065 mutations could be 0.02% and 0.05% respectively, demonstrating the clinical practicability of our proposed strategy in low abundance mutation detection.Graphical abstractImage 1
  • Ultrasensitive detection of miRNA via one-step rolling circle-quantitative
           PCR (RC-qPCR)
    • Abstract: Publication date: Available online 16 May 2019Source: Analytica Chimica ActaAuthor(s): Mingcheng Xu, Jiawei Ye, Dan Yang, Abdu Ahmed Abdullah AL-maskri, Haihong Hu, Cheulhee Jung, Sheng Cai, Su Zeng A novel microRNA (miRNA) quantification method has been developed using one-step rolling circle-quantitative PCR (RC-qPCR) analysis. Vent (exo-) DNA polymerase is firstly utilized to combine a rolling circle amplification (RCA) and qPCR in one step with high sensitivity and specificity in our RC-qPCR assay. Before performing the RC-qPCR, a padlock probe is ligated only when it is perfectly hybridized with miRNA. This ligation-based miRNA assay is highly specific for mature miRNAs, discriminating among related miRNAs that differ by as little as one nucleotide. It exhibits a dynamic range of seven orders of magnitude with a detection limit of 500 aM, and could be also used for the quantification of other small RNA molecules such as short interfering RNAs (siRNAs).Graphical abstractA novel microRNA quantification method has been developed using Rolling Circle-quantitative PCR (RC-qPCR) analysis. This RC-qPCR combines rolling circle amplification (RCA) and qPCR in one step with high sensitivity and specificity based on Vent (exo-) DNA polymerase. The former two enzymes for RCA and qPCR are replaced by Vent (exo-) DNA polymerase, which make detection more simple and time-saving. We expect our rapid, facile, and reliable PCR method will be a promising candidate for detection of miRNA in biomedical applications.Image 1
  • Development of luminescent nanoswitch for sensing of alkaline phosphatase
           in human serum based onAl3+-PPi interaction and Cu NCs with AIE properties
    • Abstract: Publication date: Available online 16 May 2019Source: Analytica Chimica ActaAuthor(s): Fenghua Geng, Changpeng Zou, Jinhua Liu, Qianchen Zhang, Xueying Guo, Yunchang Fan, Haidong Yu, Sheng Yang, Zhipeng Liu, Lin Li As an important biomarker, alkaline phosphatase (ALP) is one of the most commonly assayed enzymes in clinical practice. Here a novel turn-on fluorescent nanoswitch for ALP assay was suggested. The nanoswitch was easily constructed via two high-affinity ligands between GSH and Al3+ and PPi and Al3+ based on the difference in the affinity. The primary fluorescence of as-prepared GSH capped Cu nanoclusters (NCs) turned on first upon the Al3+ addition due to the Al3+ induced aggregation induced emission (AIE) enhancement based on the high affinity of GSH and Al3+. The presence of PPi then made Al3+ desorb from the surface of GSH capped Cu NCs due to the higher affinity of PPi and Al3+. As a result, the fluorescence of the Cu NCs was quenched. ALP could hydrolyze PPi into phosphate, destroying the PPi-Al3+ complex and releasing Al3+. Thus, the Al3+ binds to GSH again and the fluorescence was restored. The nanoswitch was demonstrated to be sensitive and selective for ALP assay and was successfully used for the ALP assay in the human serum.Graphical abstractImage 1
  • Electrocatalytic oxidation toward dopamine and acetaminophen based on
           AuNPs@TCnA/GN modified glassy carbon electrode
    • Abstract: Publication date: Available online 16 May 2019Source: Analytica Chimica ActaAuthor(s): Wenjie Liu, Qiaofang Shi, Gang Zheng, Jun Zhou, Ming Chen In this paper, gold nanoparticles (AuNPs) modified by thiolated calix[n]arene (TCnA, n=4, 6, 8) were anchored on graphene nanosheets (GN) by π-π stacking interaction between TCnA molecules and GN. Testing of various electrochemical techniques display that the AuNPs@TCnA/GN modified glass carbon electrodes (GCE) show good electrocatalytic property, molecular recognition and enrichment performance toward dopamine (DA) and acetaminophen (AC), and exhibit high current response. In all of modified electrodes, AuNPs@TC8A/GN/GCE shows an outstanding electrochemical response for DA and AC with high sensitivity of 5.08 and 9.76 mA mmol-1 L cm-2, respectively. The analytical curves for DA obtained by differential pulse voltammetry (DPV) are linear in the range from 0.5 to 150 μM and from 0.3 to 1.0 mM. The linear range for AC obtained by DPV is from 0.5 to 120 μM. Besides, AuNPs@TC8A/GN/GCE can be applied to determinate of DA and AC simultaneously, implying the prospect to develop a dual sensor under the same construction platform.Graphical abstractImage 1
  • A “switch-on” photoluminescent and electrochemiluminescent multisignal
           probe for hypochlorite via a cyclometalated iridium complex
    • Abstract: Publication date: Available online 16 May 2019Source: Analytica Chimica ActaAuthor(s): Danjuan Han, Manping Qian, Hongfang Gao, Bing Wang, Honglan Qi, Chengxiao Zhang A new cyclometalated iridium complex, [(bt)2Ir(bpy-Fc)]PF6 (bt = 2-phenylbenzothiazole, bpy-Fc = 4-ferrocenecarbonyl hydrazinocarbonyl-4’-methyl- 2,2’-bipyridine) (probe 1) was designed and synthesized for rapid photoluminescent (PL) and electrochemiluminescent (ECL) sensing of hypochlorite (ClO−). Probe 1 exhibits weak PL and ECL emissions attributed to its electron transfer process. In the presence of ClO−, the cleavage of the hydrazine-linked Fc moiety in probe 1 led to the enhancement of both PL and ECL. The photophysical and ECL properties of probe 1 were investigated and the proposed mechanism of the luminescence enhancement was confirmed by 1H nuclear magnetic resonance spectroscopy, and PL and ECL investigations. In addition, the role of the Fc group in probe 1 in intra- and intermolecular electron transfer processes in the absence and presence of ClO− is demonstrated for both PL and ECL processes. Further, a “switch-on” multi-signal method was developed for sensitive and selective detection of ClO− with detection limits of 466 nM and 302 nM via PL and ECL techniques, respectively. Further, probe 1 was successfully applied for PL imaging of ClO− in living macrophage cells. This work demonstrates that cyclometalated iridium complex bearing recognition and quenching groups is a promising “switch-on” probe in aqueous solutions to image living cells with high sensitivity and selectivity for biomedical applications.Graphical abstractImage 1
  • Identification and visualisation of microplastics by Raman mapping
    • Abstract: Publication date: Available online 16 May 2019Source: Analytica Chimica ActaAuthor(s): Zahra Sobhani, Md. Al Amin, Ravi Naidu, Mallavarapu Megharaj, Cheng Fang Recently, microplastics (MP) have emerged as global contaminants of serious concern to human and ecological health. However, identification and visualisation of MP are still a challenge, whether from wastewater, oceans, sediment or soil. Particularly when MP are mapped to visualise their distribution, the background signal from sediment and soil might be high and shield the MP signal from the analysis. Raman has recently received increasing attention, as the complementary spectrum of infrared (IR), because it can overcome the drawbacks of IR analysis including water interference, low lateral resolution and a complex spectrum. Here we show that Raman can identify and visualise MP from a soil/sand background, with almost no sample preparation, no dye, no destruction of the sample and no interference from water/organic matter/fluorescence background signals as well. By mapping image via their characteristic and fingerprint peaks, MP including polystyrene (PS), polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC) and polypropylene (PP) can be individually identified and visualised. The lateral resolution along the focal plane is 1 μm/pixel to catch small MP down to 1 μm.Graphical abstractImage 1
  • A critical retrospective and prospective review of designs and materials
           in in-line solid-phase extraction capillary electrophoresis
    • Abstract: Publication date: Available online 15 May 2019Source: Analytica Chimica ActaAuthor(s): L. Pont, R. Pero-Gascon, E. Gimenez, V. Sanz-Nebot, F. Benavente Several strategies have been developed to decrease the concentration limits of detection (LODs) in capillary electrophoresis (CE). Nowadays, chromatographic-based preconcentration using a microcartridge integrated in the separation capillary for in-line solid-phase extraction capillary electrophoresis (SPE-CE) is one of the best alternatives for high throughput and reproducible sample clean-up and analyte preconcentration. This review covers different designs (geometrical configurations, with frits or fritless, capillary types, compatibility with commercial instrumentation, etc.) and materials (sorbents, supports, affinity ligands, etc.) applied for almost 30 years to prepare in-line SPE-CE microcartridges (i.e. analyte concentrators), with emphasis on the conventional unidirectional configuration in capillary format. Advantages, disadvantages and future perspectives are analyzed in detail to provide the reader a wide overview about the great potential of this technique to enhance sensitivity and address trace analysis.Graphical abstractImage 1
  • Corrigendum to “Image-guided cancer therapy using aptamer-functionalized
           cross-linked magnetic-responsive Fe3O4@carbon nanoparticles” [Anal.
           Chim. Acta 1056 (2019) 108-116]
    • Abstract: Publication date: Available online 15 May 2019Source: Analytica Chimica ActaAuthor(s): Changhong Zhao, Xuebin Song, Weiguang Jin, Fan Wu, Qicheng Zhang, Ming Zhang, Ninglin Zhou, Jian Shen
  • Critical review of electronic nose and tongue instruments prospects in
           pharmaceutical analysis
    • Abstract: Publication date: Available online 15 May 2019Source: Analytica Chimica ActaAuthor(s): Tomasz Wasilewski, Dorian Migoń, Jacek Gębicki, Wojciech Kamysz Electronic nose (enose, EN) and electronic tongue (etongue, ET) have been designed to simulate human senses of smell and taste in the best possible way. The signals acquired from a sensor array, combined with suitable data analysis system, are the basis for holistic analysis of samples. The efficiency of these instruments, regarding classification, discrimination, detection, monitoring and analytics of samples in different types of matrices, is utilized in many fields of science and industry, offering numerous practical applications. Popularity of both types of devices significantly increased during the last decade, mainly due to improvement of their sensitivity and selectivity. The electronic senses have been employed in pharmaceutical sciences for, among others, formulation development and quality assurance. This paper contains a review of some particular applications of EN and ET based instruments in pharmaceutical industry. In addition, development prospects and a critical summary of the state of art in the field were also surveyed.Graphical abstractImage 1
  • Label-free visual biosensor based on cascade amplification for the
           detection of Salmonella
    • Abstract: Publication date: Available online 15 May 2019Source: Analytica Chimica ActaAuthor(s): Yuan Zhang, Jingjiing Tian, Kai Li, Hongtao Tian, Wentao Xu Salmonella is a widely distributed, extremely harmful bacteria, the presence of which requires confirmation via an on-site visual biosensor. In this study, we constructed a label-free, cascade amplification visualization biosensor for the sensitive and rapid detection of Salmonella enterica subsp. enterica serovar typhimurium based on the RDTG principle (recombinase polymerase amplification (RPA), duplex-specific enzyme (DSN) cleavage, terminal deoxynucleotidyl transferase (TdT) extension and G-quadruplexes output). Following DNA extraction of Salmonella spp., the first step in the construction involved the recognition and amplification of nucleic acids, carried out by RPA, to achieve the first signal amplification within 10 min. This RPA product was then specifically cleaved by DSN to produce a large number of small double-stranded DNA (dsDNA) products with 3'-OH within 15 min to achieve the second signal amplification. Thereafter, TdT was employed to empower these small 3'-OH dsDNA products to extend and produce a large number of long G-rich single-stranded DNAs (ssDNAs) within 20 min, thus realizing the third signal increase. These long G-rich ssDNA products displayed a color change that could be directly observed through the naked eye by adding H2O2/3,3’,5,5’-tetramethylbenzidine (TMB). The RDTG biosensor for the detection of Salmonella spp. has several advantages, including a low limit of 6 cfu/mL. It is an isothermal-free instrument, simple to operate, with a rapid detection time of less than 1.5 h. Furthermore, it can be visually characterized and quantified by a microplate reader to detect Salmonella spp., in food and environmental samples, and it has broad application prospects.Graphical abstractIn this paper, a label-free visual biosensor has been developed based on cascade amplification for the detection of Salmonella with several preponderant advantages, such as the RDTG design, visualization, rapidity, high sensitivity and versatility.Image 1
  • Sensitive amperometric immunosensor with improved electrocatalytic Au@Pd
           urchin-shaped nanostructures for human epididymis specific protein 4
           antigen detection
    • Abstract: Publication date: 3 September 2019Source: Analytica Chimica Acta, Volume 1069Author(s): Qin Yan, Linlin Cao, Hui Dong, Zhaoling Tan, Qing Liu, Wen Zhang, Pingping Zhao, Yueyun Li, Yuying Liu, Yunhui Dong Sensitive detection of early ovarian cancer is imminent for women's health. Human epididymis specific protein 4 antigen (HE4 Ag), as a novel tumor marker, has good specificity and sensitivity in ovarian cancer markers, especially for the detection of early ovarian cancer. In this work, a novel and ultrasensitive sandwich-type amperometric electrochemical immunosensor was constructed using amine modified graphene supported gold nanorods (Au NRs/NH2-GS) as a sensor platform and core-shell Au@Pd urchin-shaped nanostructures (Au@Pd USs) as a label of the secondary antibodies (Ab2, Au@Pd USs-Ab2) to realize the quantitative determination of HE4 Ag. The Au NRs/NH2-GS were used for increasing the electrode surface area and effectively immobilizing primary antibodies (Ab1) due to its good water-solubility. The Au@Pd USs have special morphology with high crystal surface index and good stability, capable of loading secondary antibodies (Ab2) and providing a larger active site for the catalysis of hydrogen peroxide (H2O2). The proposed immunosensor displays excellent performance for HE4 Ag detection over the range from 1 pmol L−1 to 50 nmol L−1 with a detection limit of 0.33 pmol L−1 (signal-to-noise ratio of 3). Moreover, the designed immunosensor exhibits excellent reproducibility, selectivity, and stability, which shows great potential in clinical diagnosis.Graphical abstractA novel and ultrasensitive sandwich-type electrochemical immunosensor was constructed using amine modified graphene supported gold nanorods (Au NRs/NH2-GS) as sensor platform and the improved electrocatalytic bimetallic Au@Pd urchin-shaped nanostructures (Au@Pd USs) as label for the quantitative determination of human epididymis specific protein 4 antigen (HE4 Ag).Image 1
  • Self-heated Ag-decorated SnO2 nanowires with low power consumption used as
           a predictive virtual multisensor for H2S-selective sensing
    • Abstract: Publication date: 3 September 2019Source: Analytica Chimica Acta, Volume 1069Author(s): Trinh Minh Ngoc, Nguyen Van Duy, Chu Manh Hung, Nguyen Duc Hoa, Hugo Nguyen, Matteo Tonezzer, Nguyen Van Hieu Multisensor systems with low-power consumption are emerging for the Internet of Things. In this work, we demonstrate the use of self-heated networked Ag-decorated SnO2 NW sensors integrated into a portable module for selective detection of H2S gas at low power consumption, and the integrated system is simulated as a virtual multisensor under varying heating powers for identifying and quantifying different reducing gases. The H2S gas-sensing characterisations at the different self-heating powers of 2–10 mW showed that the gas response significantly increased with the increase in Ag density decoration and the heated power strongly affected the gas-sensing performance and sensor stability. Excellent response of 21.2 to 0.5 ppm H2S gas was obtained at a low heating power of 2 mW with an acceptable response/recovery time of 18/980 s. The increase of the heating power over 20 mW can destroy the devices. The integrated system could selectively detect H2S at the heating power below 4 mW and H2, C2H5OH and NH3 gases at the heating power upon 4 mW. The virtual multisensor could discriminate qualitatively (with an accuracy of 100%) and quantitatively H2S, H2, NH3, C2H5OH (Ethanol) and CH3COCH3 (Aceton) gases with average errors of 13.5%, 14.7%, 16.8%, 16.9%, and 14.8%, respectively. The proposed sensing platform is a promising candidate for selective detection of H2S gas and virtual multisensor with low power consumption for mobile or wireless network devices.Graphical abstractImage 1
  • Advanced liquid chromatography-mass spectrometry enables merging widely
           targeted metabolomics and proteomics
    • Abstract: Publication date: 3 September 2019Source: Analytica Chimica Acta, Volume 1069Author(s): Wenjing Liu, Qingqing Song, Yan Cao, Yanan Zhao, Huixia Huo, Yitao Wang, Yuelin Song, Jun Li, Pengfei Tu Either widely targeted metabolomics or quantitative proteomics usually requires unique analytical platform. However, cross-platform omics studies entail higher levels of complexity and uncertainty, and result in a significant obstacle for high throughput assay as well. It is thereby urgent to pursue an integrative approach being capable of merging these two omics terms, namely widely targeted bi-omics. As an eligible analytical tool for large-scale targeted metabolomics, reversed phase liquid chromatography-hydrophilic interaction liquid chromatography–tailored selected reaction monitoring (RPLC-HILIC–tailored SRM) was deployed here to further receive the tryptic peptides as the analytes. Comparative evaluation of metabolites and tryptic peptides, 101 ones in total, between HepG2 and SK-Hep1 cells was conducted as a proof-of-concept. All analytes, regardless of metabolites or peptides, exhibited satisfactory chromatographic behaviors on RPLC-HILIC. Quantitative MS parameters, such as SRM transitions and collision energies (CEs), of either tryptic peptides or metabolites were online optimized in a standard compound-independent manner. It was worthwhile to mention that the signal responses of the peptides-of-choice generated by the optimized CEs were significantly superior to those values suggested by Skyline software. Calibration curves of both metabolites and peptides were constructed by serially diluting a so-called universal metabolome standard (UMS) sample. The quasi-content of each peptide or metabolite was gained according to applying those regressive calibration curves. After subjecting the quasi-content dataset into SIMCA-P software, significant differences took place between the two hepatic cell lines, and not only metabolites but tryptic peptides contributed to the discrimination. Above all, RPLC-HILIC–tailored SRM offered a promising choice towards widely targeted bi-omics attributing to the advantage of simultaneous monitoring metabolites and tryptic peptides.Graphical abstractImage 1
  • Determination of nerve agent metabolites in human urine by femtosecond
           laser ionization mass spectrometry using 2-(bromomethyl)naphthalene as a
           derivatizing reagent
    • Abstract: Publication date: 3 September 2019Source: Analytica Chimica Acta, Volume 1069Author(s): Vu Van Son, Hiroshi Nakamura, Tomoko Imasaka, Totaro Imasaka Nerve agent metabolites (NAMs) derived from alkyl methyl phosphonic acids, such as ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA), and pinacolyl methylphosphonic acid (PMPA), were extracted from human urine using diethyl ether as an extractant. After exchanging the diethyl ether solvent to acetonitrile, the analytes were derivatized with 2-(bromomethyl)naphthalene (BMN). The reaction products of the BMN and NAMs, i.e., MN-EMPA, MN-IMPA, and MN-PMPA, were separated by gas chromatography (GC) and measured by mass spectrometry (MS) using a femtosecond laser emitting at 267 nm as the ionization source for resonance-enhanced two-photon ionization (RE2PI). The limits of detection (LOD) were
  • An amplification strategy using DNA-Peptide dendrimer probe and mass
           spectrometry for sensitive MicroRNA detection in breast cancer
    • Abstract: Publication date: 3 September 2019Source: Analytica Chimica Acta, Volume 1069Author(s): Liang Liu, Yuqiong Kuang, Hong Yang, Yun Chen MicroRNAs (miRNAs) are emerging as novel biomarkers for diagnosis and treatment of various cancers, including breast cancer. Because the value of biomarkers primarily depends on whether they are quantifiable, great effort has been taken to develop assays for sensitive and accurate quantification of miRNAs. However, most of current assays have high nonspecific amplification effect, which limits quantification accuracy. In this study, we circumvented copying of nucleic acid sequence and developed a signal amplification strategy based on a novel DNA-peptide dendrimer (DPD) probe coupled with mass spectrometry. The DPD probe RP8-MAP4-DNA contained three functional domains, including substrate peptides containing eight reporter peptides and tryptic cleavage sites, peptide dendrimer scaffold and DNA complementary to target miRNA. The probe was first hybridized with the target miRNA (i.e., miR-21) that was biotinylated and attached to streptavidin agarose in advance. After trypsin digestion, the reporter peptide was liberated and quantified using LC-MS/MS. The signal intensity was approximately 8 fold greater than that without signal amplification. Finally, the developed assay was applied for the quantitative analysis of miR-21 in 3 human breast cell lines and 102 matched pairs of breast tissue samples. The miR-21 expression in tissue was also evaluated depend on histopathological features, molecular subtypes and prognosis of breast cancer. The result demonstrated that combination of DPD probe and mass spectrometry is a promising strategy for quantification of miRNAs and illustration of their biomarker potential, especially those at low abundance.Graphical abstractImage 1
  • Rapid screening of formaldehyde in food using paper-based titration
    • Abstract: Publication date: 3 September 2019Source: Analytica Chimica Acta, Volume 1069Author(s): Natchanon Taprab, Yupaporn Sameenoi A simple paper-based analytical device (PAD) has been developed to rapidly detect formaldehyde (FA) in food samples. The analysis was based on sulfite assay where FA reacted with excess sulfite to generate sodium hydroxide (NaOH) that was quantified on PAD using acid-base titration. The PAD consisted of a central sample zone connected to ten reaction and detection zones. All detection zones were pre-deposited with polyethylene glycol (PEG) with phenolphthalein (Phph) as an indicator. Reaction zones contained different amounts of the titrant, potassium hydrogen phthalate (KHP). On flowing into reaction zones, the NaOH product reacts with KHP to reach the end point. In the presence of excess NaOH, unneutralized NaOH reached the detection zone and caused Phph color change from colorless to pink. In contrast, when NaOH was less than KHP, the detection zone remained colorless. Concentration of FA can be quantified from the number of pink detection zone(s) which were correlated with a known amount of pre-deposited KHP on the PAD. Total analytical process could be completed within 5 min. Areas of each zone and amounts of reagents added to the corresponding zones of the PAD were optimized to obtain reproducible and accurate results. PAD gave ranges of FA detection of 100–1000 mg L−1 with an interval of 100 mg L−1 and the limit of detection (LOD) was 100 mg L−1. PADs were stable for up to a month under dark and cold conditions. Analysis of FA in food samples using PAD agreed well with those from the classical sulfite assay.Graphical abstractImage 1
  • A green and simple sample preparation method to determine pesticides in
           rice using a combination of SPME and rotating disk sorption devices
    • Abstract: Publication date: 3 September 2019Source: Analytica Chimica Acta, Volume 1069Author(s): Eduarda Omena, Anderson Luiz Oenning, Josias Merib, Pablo Richter, Milton Rosero-Moreano, Eduardo Carasek In this study, a novel environmentally-friendly approach was developed to overcome certain limitations in the analysis of solid food samples. An experimental setup based on solid-phase microextraction apparatus coupled to a rotating disk device is proposed for the determination of polar and slightly-polar pesticides including carbofuran, molinate, atrazine, simazine and tebuconazole in rice samples. In this innovative procedure, a rice sample is inserted into the cavity of the rotating disk device which is then immersed in an aqueous solution followed by high-speed agitation. In this case, water is employed as a green solvent for leaching the analytes from the sample matrix. Simultaneously, a solid-phase microextraction fiber comprised of divinylbenzene/carboxen/polydimethylsiloxane (2 cm length and 50/30 μm film thickness) was immersed in the aqueous solution to extract the slightly polar analytes from the aqueous matrix with subsequent thermal desorption in the injector of a gas chromatograph-mass spectrometer instrument. The optimal extraction conditions were obtained using an extraction temperature of 80 °C for 40 min, with 125 mg of rice inserted in the rotating disk. Using the previously optimized extraction conditions, the analytical performance was satisfactory with correlation coefficients higher than 0.9881 for all analytes, limits of detection ranging from 0.46 to 5.9 ng g−1, limits of quantification from 1.5 to 19.7 ng g−1, relative recoveries from 76 to 109%, intra-day precision (n = 3) from 1.3 to 19%, and inter-day precision (n = 9) from 3.5 to 6.5%. The proposed method represents a promising alternative for the analysis of complex solid food samples using SPME, since the SPME fiber damage is substantially decreased when the contact with the solid matrix is avoided.Graphical abstractImage 1
  • Outside Front Cover
    • Abstract: Publication date: 3 September 2019Source: Analytica Chimica Acta, Volume 1069Author(s):
  • Hg-supported phospholipid monolayer as rapid screening device for low
           molecular weight narcotic compounds in water
    • Abstract: Publication date: 3 September 2019Source: Analytica Chimica Acta, Volume 1069Author(s): N. William, A. Nelson, S. Gutsell, G. Hodges, J. Rabone, A. Teixeira This study positions the fabricated Pt/Hg-supported phospholipid sensor element in the context of more conventional biomembrane-based screening platforms. The technology has been used together with immobilised artificial membrane (IAM) chromatography and COSMOmic simulation methods to screen the interaction of a series of low molecular weight narcotic organic compounds in water with phosphatidylcholine (PC) membranes. For these chemicals it is shown that toxicity to aquatic species is related to compound hydrophobicity which is associated with compound accumulation in the phospholipid membrane as modelled by IAM chromatography measurements and COSMOmic simulations. In contrast, the Hg-supported dioleoyl phosphatidylcholine (DOPC) sensor element records membrane damage/modification which is indirectly related to general toxicity and directly related to compound structure. Electrochemical limit of detection (LoD) values depend on molecular structure and range from 20 μmolL−1 for substituted phenols to 23 mmolL−1 for aliphatics. Rapid cyclic voltammetry (RCV) “fingerprints” showed that the major structural classes of compounds: alkyl/chlorobenzenes, substituted phenols, quaternary ammonium compounds and neutral amines interacted distinctively with the DOPC on Hg and that these observations correlated with and supported those predicted by the COSMOmic simulations of the compound/DMPC association. In addition, the compatibility of the electrochemical and COSMOmic methods validates the electrochemical device as a meaningful high throughput technology to screen compounds in water and report on the mechanistic details of their interaction with phospholipid layers.Graphical abstractImage 1
  • UV photoionization ion mobility spectrometry: fundamentals and
    • Abstract: Publication date: Available online 11 May 2019Source: Analytica Chimica ActaAuthor(s): Chuang Chen, Dandan Jiang, Haiyang Li UV photoionization (UV-PI) is a promising non-radioactive ionization method for ion mobility spectrometry (IMS). It could work at either direct photoionization mode or chemical ionization mode by adding photoionizable dopants, and thus its applications extend to a wide range of compound classes. This work is to present a comprehensive review on the development of UV-PI-IMS. It focuses on UV-PI’s capabilities and how to use them fully. A summary discussion of the ionization processes in UV-PI would be presented first for understanding the fundamentals of UV-PI-IMS. Followed by descriptions of the technical configurations of UV-PI source in IMS. Improvements in the design of UV-PI source for achieving optimum results will be presented with references to examples. Further, a broad range of applications, including environmental contaminants analysis, trace explosives and chemical warfare agents detection, food safety and quality analysis, and clinical diagnosis, would be presented to demonstrated the analytical performance of UV-PI-IMS. In the conclusion, perspectives on areas of UV-PI technique which have the potential to be improved would be reasonably presented.Graphical abstractImage 1
  • Automated lab-on-valve sequential injection ELISA for determination of
    • Abstract: Publication date: Available online 9 May 2019Source: Analytica Chimica ActaAuthor(s): Inês I. Ramos, Peter Carl, Rudolf J. Schneider, Marcela A. Segundo The development of an automated miniaturized analytical system that allows for the rapid monitoring of carbamazepine (CBZ) levels in serum and wastewater is proposed. Molecular recognition of CBZ was achieved through its selective interaction with microbeads carrying anti-CBZ antibodies. The proposed method combines the advantages of the micro-bead injection spectroscopy and of the flow based-platform lab-on-valve for implementation of automatic immunosorbent renewal, rendering a new recognition surface for each sample. The sequential (or simultaneous) perfusion of CBZ and the horseradish peroxidase-labeled CBZ through the microbeads is followed by real-time on-column monitoring of substrate (3,3′,5,5′-tetramethylbenzidine) oxidation by colorimetry. The evaluation of the initial oxidation rate and also the absorbance value at a fixed time point provided a linear response versus the logarithm of the CBZ concentration. Under the selected assay conditions, a single analysis was completed after only 11 min, with a quantification range between 1.0 and 50 μg L-1. Detection of CBZ levels in undiluted wastewater samples was feasible after a simple filtration step while good recoveries were attained for spiked certified human serum, analyzed without sample clean-up.Graphical abstractImage 1
  • Preconcentration and sensitive determination of the anti-inflammatory drug
           diclofenac on a paper-based electroanalytical platform
    • Abstract: Publication date: Available online 9 May 2019Source: Analytica Chimica ActaAuthor(s): E. Costa-Rama, H.P.A. Nouws, C. Delerue-Matos, M.C. Blanco-López, M.T. Fernández-Abedul This work describes the development of a paper-based platform for highly sensitive detection of diclofenac. The quantification of this anti-inflammatory drug is of importance in clinical (e.g. quality- and therapeutic control) and environmental (e.g. emerging contaminant determination) areas. The easy-to-handle platform here described consists of a carbon-ink paper-based working electrode and two metallic wires, provided by a gold-plated standard connector, as reference and counter electrodes. The porous paper matrix enables the preconcentration of the sample, decoupling sample and detection solutions. Thus, relatively large sample volumes can be used, which significantly improves the sensitivity of the method. A wide dynamic range of four orders of magnitude, between 0.10 and 100 μM, was obtained for diclofenac determination. Due to the predominance of adsorption at the lowest concentrations, there were two linear concentration ranges: one comprised between 0.10 and 5.0 μM (with a slope of 0.85 μA μM-1) and the other between 5.0 and 100 μM (with a slope of 0.48 μA μM-1). A limit of detection of 70 nM was achieved with this simple device. The platform provided accurate results with an RSD of ca. 5%. It was applied for diclofenac quantification in spiked tap water samples. The versatility of this design enabled the fabrication of a multiplexed platform containing eight electrochemical cells that work independently. The low cost, small size and simplicity of the device allow on-site analysis, which is very useful for environmental monitoring.Graphical abstractImage 1
  • Fluorescent probe for sensitive discrimination of Hcy and Cys/GSH in
           living cells via dual-emission
    • Abstract: Publication date: Available online 8 May 2019Source: Analytica Chimica ActaAuthor(s): Shuang Xu, Junliang Zhou, Xiaochun Dong, Weili Zhao, Quangang Zhu Abnormal levels of Cys, Hcy and GSH are associated with various diseases, thus monitoring biothiols is of great significance. In this work, a dual-emission responsive near-infrared fluorescent probe NIR-NBD for detecting Hcy and Cys/GSH was developed based on the conjugation of a dicyanoisophorone based fluorophore (NIR-OH) and 7-nitrobenzofurazan (NBD). To our surprise, the addition of Hcy induced significant fluorescence enhancement at both 549 and 697 nm; while Cys/GSH resulted in major fluorescence emission at 697 nm. The detection limit was determined to be 33.2 nM for Cys, 33.5 nM for Hcy, and 34.4 nM for GSH. Therefore, the probe can be used for discriminative detection of Hcy and Cys/GSH. Moreover, fluorescence imaging of HeLa cells indicated that the probe was cell membrane permeable and could be used for visualizing Hcy and Cys/GSH in living cells.Graphical abstractImage 1
  • Proximity hybridization-induced on particle DNA walker for ultrasensitive
           protein detection
    • Abstract: Publication date: Available online 8 May 2019Source: Analytica Chimica ActaAuthor(s): Haiying Gan, Jie Wu, Huangxian Ju A simple proximity hybridization-induced on particle DNA walker was designed for ultrasensitive detection of proteins, for example platelet-derived growth factor (PDGF-BB) secreted by cancer cells, in which the DNA walker was activated by specific target binding and powered by an enzymatic cleavage to produce amplified signal. High-density FAM-labeled hairpin oligonucleotides (FAM-DNA1) were functionalized on AuNPs to construct three-dimensional (3D) DNA tracks. The specific binding of PDGF-BB with two aptamer probes (DNA3 and DNA4) led to the proximity hybridization-induced DNA displacement and the free of DNA walker (DNA2) to perform movement on the 3D tracks by an enzymatic cleavage, resulting in the release of massive FAM-DNA1 fragments from the AuNPs and the generation of fluorescent signal. This DNA walker based sensing strategy could detect PDGF-BB in a concentration range of 4 orders of magnitude with a detection limit down to sub-pM level. The practical applicability of the assay was demonstrated by detecting PDGF-BB secreted from MCF-7 cells with satisfactory results. The proposed DNA walker based assay could conveniently detect PDGF-BB with high sensitivity and good accuracy, along with the good extensibility of the assay, showing promise for practical diagnosis.Graphical abstractImage 1
  • Low-molecular-mass nitrophenol-based compounds suitable for the effective
           tracking of pH gradient in isoelectric focusing
    • Abstract: Publication date: Available online 8 May 2019Source: Analytica Chimica ActaAuthor(s): Filip Duša, Dana Moravcová, Karel Šlais Low-molecular-mass isoelectric point (pI) markers are a reasonable alternative to commonly used peptide and protein pI markers in the field of isoelectric focusing. We present a comparative study dealing with characterization of 44 nitrophenol-based compounds synthesized by the Mannich reaction which pI values cover a pH range from 3.2 to 10.4. The values of pIs of all the presented nitrophenol-based compounds were precisely determined by capillary isoelectric focusing technique (cIEF) when a standard deviation of measurement reached a value of a few hundredths of a pH unit (n ≥ 3). Differences have been found between in silico analysis of acid-base properties of the investigated compounds and the experimental cIEF data especially at the basic pH region. The data from the acidic pH range showed better correlation between these methods. Only three compounds were excluded from the group of pI markers because they contained impurities originating from the synthesis or long-term storage. Based on the presented results we identified 41 nitrophenol-based pI markers (NPIMs) which can fulfill requirements of the most applications in a field of isoelectric focusing analyses.Graphical abstractImage 1
  • Electrochemical Biosensor for Methyl Parathion Based on Single-Walled
           Carbon Nanotube/Glutaraldehyde Crosslinked Acetylcholinesterase-Wrapped
           Bovine Serum Albumin Nanocomposites
    • Abstract: Publication date: Available online 8 May 2019Source: Analytica Chimica ActaAuthor(s): T.H. Vignesh Kumar, Ashok K. Sundramoorthy Semiconducting single-walled carbon nanotubes (s-SWCNTs) have demonstrated as excellent material for transistors, miniaturized devices and sensors due to their high carrier mobility, stability, scattering-free ballistic transport of carriers etc. Herein, we have designed a biosensor to selectively detect methyl parathion (MP, organophosphorus pesticide) using glutaraldehyde (Glu) cross-linked with acetylcholinesterase (AChE) immobilized on s-SWCNTs wrapped with bovine serum albumin (BSA). The fabricated biosensor was characterized and confirmed by Fourier-transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). In the presence of MP, the effective interaction between AChE and MP favours the accumulation of MP-AChE complex on the glassy carbon electrode (GCE) surface which reduces the electron transfer property. Based on this interaction, detection of various concentration of MP was demonstrated by SWV using BSA/AChE-Glu-s-SWCNTs composite modified electrode. The proposed biosensor exhibited a wide linear range (WLR) for MP target in 100 mM phosphate buffered saline solution (PBS) (pH 7.4) from 1 × 10-10 M to 5 × 10-6 M with a limit of detection (LOD) of 3.75×10-11 M. In addition, the BSA/AChE-Glu-s-SWCNTs/GCE biosensor showed good repeatability and reproducibility for MP detection. Moreover, the proposed biosensor showed better electrode stability when stored at 4°C. This new electrochemical biosensor is also exhibited high selectivity and sensitivity for MP, which made it possible to test MP in real strawberry and apple juices. Furthermore, the BSA/AChE-Glu-s-SWCNTs/GCE offered a favourable electron transfer between the target MP and electrode interface than BSA/AChE-s-SWCNTs/GCE, s-SWCNTs/GCE and bare GCE.Graphical abstractImage 1
  • Functional chimera aptamer and molecular beacon based fluorescent
           detection of Staphylococcus aureus with strand displacement-target
           recycling amplification
    • Abstract: Publication date: Available online 8 May 2019Source: Analytica Chimica ActaAuthor(s): Rongfeng Cai, Fan Yin, Zhongwen Zhang, Yaping Tian, Nandi Zhou A fluorescent detection of Staphylococcus aureus (S. aureus) is established based on a finely designed functional chimera sequence, a molecular beacon (MB), and strand displacement target recycling. The chimera sequence, which consists of the aptamer sequence of S. aureus and the complementary sequence of MB, can form a hairpin structure due to the existence of intramolecular complementary regions. When S. aureus is present, it binds to the aptamer region of the chimera, opens the hairpin and unlocks the complementary sequence of MB. Subsequently, the MB is opened and intensive fluorescence signal is restored. To increase the sensitivity of the detection, signal amplification is achieved through strand displacement-based target recycling. With the catalysis of Nb. Bpu10I nicking endonuclease and Bsm DNA polymerase, the MB sequence can be cleaved and then elongated to form a complete duplex with the chimera, during which S. aureus is displaced from the chimera and proceeded to the next round of the reaction. This assay displays a linear correlation between the fluorescence intensity and the logarithm of the concentration of S. aureus within a broad concentration range from 80 CFU/mL to 8×106 CFU/mL. The detection limit of 39 CFU/mL can be derived. The assay was applied to detect S. aureus in different water samples, and satisfactory recovery and repeatability were achieved. Hence the designed chimera sequence and established assay have potential application in environmental pollution monitoring.Graphical abstractImage 1
  • Electrochemical detection of Salmonella using an invA genosensor on
           polypyrrole-reduced graphene oxide modified glassy carbon electrode and
           AuNPs-horseradish peroxidase-streptavidin as nanotag
    • Abstract: Publication date: Available online 8 May 2019Source: Analytica Chimica ActaAuthor(s): Yongkang Ye, Wuwen Yan, Yaqian Liu, Shudong He, Xiaodong Cao, Xuan Xu, Haisong Zheng, Sundaram Gunasekaran A rapid and sensitive electrochemical biosensor was constructed to detect Salmonella using invA gene biosensor. The biosensing was based on polyrrole-reduced graphene oxide (PPy-rGO) nanocomposite modified glassy carbon electrode (GCE) and signal amplification with horseradish peroxidase-streptavidin biofunctionalized gold nanoparticles (AuNPs-HRP-SA). PPy-rGO was prepared at 60 °C by chemical reduction of PPy-functionalized graphene oxide (PPy-GO) that was synthesized by in situ polymerization at room temperature. The detection signal was amplified via enzymatic reduction of H2O2 in the presence of hydroquinone (HQ) using AuNPs-HRP-SA as nanotag. Under optimal conditions, the differential pulse voltametric (DPV) signal from the biosensor was linearly related to the logarithm of target invA gene concentrations from 1.0 × 10-16 to 1.0 × 10-10 M, and the limit of detection (LOD) was 4.7×10-17 M. The biosensor can also detect Salmonella in the range of 9.6 to 9.6×104 CFU mL-1, with LOD of 8.07 CFU mL-1. The biosensor showed good regeneration ability, acceptable selectivity, repeatability and stability, which bode well as an alternative method for Salmonella screening.Graphical abstractImage 1
  • Determination of Polybrominated Diphenyl Ethers in Fish Tissue Using Gas
           Chromatography-Isotope Dilution Tandem Inductively Coupled Plasma Mass
           Spectrometry with a Mass-Shift Mode
    • Abstract: Publication date: Available online 7 May 2019Source: Analytica Chimica ActaAuthor(s): Chi Zhang, Xiaomin Li, Hongmei Li, Yanling Chen, Tingting Ma, Xiuqin Li, Yan Gao, Qinghe Zhang Gas chromatography inductively coupled plasma triple quadrupole mass spectrometry (GC-ICP-MS/MS) operated in N2O reaction mode (mass-shift mode) was established for the analysis of six congeners of polybrominated diphenyl ethers (PBDEs): BDE 28, BDE 47, BDE 99, BDE 100, BDE 153 and BDE 154 in fish samples. The spectral interference on the determination of PBDEs was eliminated by measuring the product ion (BrO+) instead of traditional methods measuring Br+. After comparing the signal intensities of the three reaction gases (O2, H2, and N2O), the highest sensitivity was found using N2O as the reaction gas. The results showed that bromine is an element that suffers from strong spectral overlap in ICP, mainly from Ar-based polyatomic interferences. Spectral interference was assessed by measuring the bromine isotope ratio of 81Br+ and 79Br+ of the six priority PBDEs in the He collision mode and N2O reaction mode, respectively. In the conventional He collision mode, the relative isotope ratio of 79Br/81Br (the measured isotope ratio to the natural isotope ratio) of the analytes ranged from 0.955 to 0.965, which proves that using He as the collision gas cannot completely eliminate the spectral interference. In the N2O reaction mode, the relative isotope ratio of 79Br/81Br ranged from 0.991 to 1.004, demonstrating that spectral interference can be fully eliminated. Samples were processed using the modified QuEChERs method with detection limits ranging from 0.03 to 0.09 ng g-1 with a relative standard deviation of less than 3%. Six priority PBDEs in the NIST reference materials SRM 1947 (frozen fish tissue homogenate) were determined by mass-shift mode to verify this conclusion. No statistically significant difference was observed between the measured value and the certified value, with recoveries between 95% and 114%. The method was applied to the analysis of PBDEs in marine fish samples and five PBDEs were observed (BDE28,BDE-47, BDE-99, BDE-100 and BDE-153) at concentrations ranging from 0.04 to 0.54 ng g-1.Graphical abstractImage 1
  • Extracellular electron transfer features of Gram-positive bacteria
    • Abstract: Publication date: Available online 7 May 2019Source: Analytica Chimica ActaAuthor(s): Galina Pankratova, Lars Hederstedt, Lo Gorton Electroactive microorganisms possess the unique ability to transfer electrons to or from solid phase electron conductors, e.g., electrodes or minerals, through various physiological mechanisms. The processes are commonly known as extracellular electron transfer and broadly harnessed in microbial electrochemical systems, such as microbial biosensors, microbial electrosynthesis, or microbial fuel cells. Apart from a few model microorganisms, the nature of the microbe-electrode conductive interaction is poorly understood for most of the electroactive species. The interaction determines the efficiency and a potential scaling up of bioelectrochemical systems.Gram-positive bacteria generally have a thick electron non-conductive cell wall and are believed to exhibit weak extracellular electron shuttling activity. This review highlights reported research accomplishments on electroactive Gram-positive bacteria. The use of electron-conducting polymers as mediators is considered as one promising strategy to enhance the electron transfer efficiency up to application scale. In view of the recent progress in understanding the molecular aspects of the extracellular electron transfer mechanisms of Enterococcus faecalis, the electron transfer properties of this bacterium are especially focused on.Fundamental knowledge on the nature of microbial extracellular electron transfer and its possibilities can provide insight in interspecies electron transfer and biogeochemical cycling of elements in nature. Additionally, a comprehensive understanding of cell-electrode interactions may help in overcoming insufficient electron transfer and restricted operational performance of various bioelectrochemical systems and facilitate their practical applications.Graphical abstractImage 1
  • Possibilities and drawbacks of total reflection X-ray fluorescence
           spectrometry as a fast, simple and cost-effective technique for
           multielement analyses of cosmetics
    • Abstract: Publication date: Available online 7 May 2019Source: Analytica Chimica ActaAuthor(s): E.Marguí, R. Dalipi, L.Borgese, L.E. Depero, I.Queralt This paper shows a simple, rapid and cost-effective method for multielement analyses of cosmetics. Total reflection X-ray fluorescence spectrometry (TXRF) is used to determine the composition, particularly the presence of potentially toxic elements, of cosmetics. Three sample preparation methods based on suspension preparation were developed for different types of cosmetic samples, e.g. lipsticks, eye shadows and body creams.Limits of detection within the low mg kg-1 range were obtained and enabled cosmetic screening for compliance with the legal thresholds for some major toxic elements. A good accuracy of the results on a wide range of concentration levels (>10000 mg kg-1) was found without the need of sample dilution. Results obtained for most elements in the lipstick and cream samples agreed with those obtained by the reference method recommended by the Food and Drug Administration, based on using inductively coupled plasma techniques after microwave digestion. However, for eyeshadow analysis, a more sophisticate approach is needed to improve the analytical results.Graphical abstractImage 1
  • Post-Synthesis Functionalized Hydrogel Microparticles for High Performance
           microRNA Detection
    • Abstract: Publication date: Available online 7 May 2019Source: Analytica Chimica ActaAuthor(s): Yoon Ho Roh, Hyun Jee Lee, Hyun June Moon, Sun Min Kim, Ki Wan Bong Encoded hydrogel microparticles, synthesized by Stop Flow Lithography (SFL), have shown great potential for microRNA assays for their capability to provide high multiplexing capacity and solution-like hybridization kinetics. However, due to the low conversion of copolymerization during particle synthesis, current hydrogel microparticles can only utilize ∼10% of the input probes that functionalize the particles for miRNA assay. Here, we present a novel method of functionalizing hydrogel microparticles after particle synthesis by utilizing unconverted double bonds remaining inside the hydrogel particles to maximize functional probe incorporation and increase the performance of miRNA assay. This allows covalent bonding of functional probes to the hydrogel network after particle synthesis. Because of the abundance of the unconverted double bonds and accessibility of all probes, the probe density increases about 8.2 times compared to that of particles functionalized during the synthesis. This results lead to an enhanced miRNA assay performance that improves the limit of detection from 4.9 amol to 1.5 amol. In addition, higher specificity and shorter assay time are achieved compared to the previous method. We also demonstrate a potential application of our particles by performing multiplexed miRNA detections in human plasma samples.Graphical abstractImage 1
  • Capillary electrophoresis of small ions and molecules in less conventional
           human body fluid samples: A review
    • Abstract: Publication date: Available online 7 May 2019Source: Analytica Chimica ActaAuthor(s): Petr Kubáň, Miloš Dvořák, Pavel Kubáň In recent years, advances in sensitive analytical techniques have encouraged the analysis of various compounds in biological fluids. While blood serum, blood plasma and urine still remain the golden standards in clinical, toxicological and forensic science, analyses of other body fluids, such as breast milk, exhaled breath condensate, sweat, saliva, amniotic fluid, cerebrospinal fluid, or capillary blood in form of dried blood spots are becoming more popular. This review article focuses on capillary electrophoresis and microchip electrophoresis of small ions and molecules (e.g. inorganic cations/anions, basic/acidic drugs, small acids/bases, amino acids, peptides and other low molecular weight analytes) in various less conventional human body fluids and hopes to stimulate further interest in the field.Graphical abstractImage 1
  • Rational design and facile synthesis of binary metal sulfides VS2-SnS2
           hybrid with functionalized multiwalled carbon nanotube for the selective
           detection of neurotransmitter dopamine
    • Abstract: Publication date: Available online 6 May 2019Source: Analytica Chimica ActaAuthor(s): Rajalakshmi Sakthivel, Subbiramaniyan Kubendhiran, Shen-Ming Chen, Jeyaraj Vinoth Kumar In this work, we report a sensitive and selective electrochemical sensor for the detection of dopamine (DA) neurotransmitter based on VS2-SnS2/f-MWCNT hybrids. Herein, the binary metal sulfide (VS2-SnS2) was synthesized via single step hydrothermal route and hybrids with f-MWCNT via the ultrasonication process. The as-prepared VS2-SnS2/f-MWCNT hybrids were characterized through the FESEM, EDX and elemental mapping, TEM, XPS, Raman and XRD techniques. The electrochemical performance and catalytic activity of the modified electrodes were probed using electrochemical impedance spectra (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Interestingly, DPV results exhibits an appreciable linear range from 0.025 to 1017 μM and LOD of 0.008 μM. The selectivity study was performed to prove the high selectivity of the VS2-SnS2/f-MWCNT hybrids modified electrode. Furthermore, the practical applicability of the DA sensor was scrutinized in human serum sample and rat brain sample.Graphical abstractImage 1
  • Simultaneous and direct determination of urea and creatinine in human
           urine using a cost-effective flow injection system equipped with in-house
           contactless conductivity detector and LED colorimeter
    • Abstract: Publication date: Available online 6 May 2019Source: Analytica Chimica ActaAuthor(s): Sumonmarn Chaneam, Kamparnart Kaewyai, Thitirat Mantim, Rasamee Chaisuksant, Prapin Wilairat, Duangjai Nacapricha This work presents a cost-effective and simple flow injection analysis (FIA) system for simultaneous and direct determination of urea and creatinine in human urine. The FIA system comprises two in-house detectors, a contactless conductivity detector and a light emitting diode (LED) detector. The contactless detector was built as a flow-through detection cell with axial electrodes, commonly known as capacitively coupled contactless conductivity detector (C4D) and the diode detector was fabricated based on the concept of paired emitter detector diodes (PEDD). With appropriate dilution of urine, the sample is directly injected into a stream of glycine-NaOH buffer pH 8.8 (the gas donor stream) and is carried by the carrier through a urease minicolumn for on-line enzymatic hydrolysis. The generated NH3 diffuses from the carrier stream through a porous polytetrafluoroethylene (PTFE) membrane into a stream of deionized water (the acceptor stream) leading to an increase in the signal at the C4D due to the NH3 dissolution in the water. In this system, creatinine is determined based on the Jaffé reaction by merging a stream of alkaline picrate with the gas donor stream. The change in color is detected using the PEDD equipped with two green LEDs. Under the optimum condition, the linear range of urea and creatinine were 30-240 mg L-1 and 10-500 mg L-1, with limits of detection of 9.0 mg L-1 and 0.9 mg L-1, respectively. The proposed system provides satisfactorily good precision (RSD < 3%), with sample throughput of 31 sample h-1 for the two analytes. The FIA system tolerates potential interference commonly found in human urine. The system was successfully applied and validated with selected reference methods.Graphical abstractImage 1
  • Activity-based Analysis of Potentiometric pH Titrations
    • Abstract: Publication date: Available online 6 May 2019Source: Analytica Chimica ActaAuthor(s): Somaiyeh Khodadadi Karimvand, Xuan Anh Nguyen, Hamid Abdollahi, Robert Burns, Sarah Clifford, Marcel Maeder, Nichola McCann, Yorck-Michael Neuhold, Graeme Puxty The discrepancy between concentrations and activities is a predicament well known to the analytical chemist. Because of the difficulty of determining activity coefficients, the standard technique for quantitative equilibrium studies is to work under a particular ‘constant ionic strength’ by adding an excess of an inert salt. Under such conditions, activity coefficients are approximately constant and can be taken into the equilibrium constants which are defined for the chosen ionic strength (I). Here we propose a fundamentally different approach. Throughout the numerical analysis of the titration data, activity coefficients for all individual species are approximated by well-known equations based on the work of Debye-Hückel. The computational analysis of the measurements strictly obeys the law of mass conservation and obeys the law of mass action only approximately. The main novelty is that now the addition of inert salts is no longer required and measurements are done at minimal I. Consequently, the the thermodynamic equilibrium constants are now determined much more robustly based on experiments taken at low I. The approach has been tested and validated with the two very well investigated 3-protic phosphoric and citric acids. In summary: the technique of artificially keeping ionic strength constant has been made replaced by improved computational analysis.Graphical abstractImage 1
  • A sensitive method for the determination of tobacco-specific nitrosamines
           in mainstream and sidestream smokes of combustion cigarettes and heated
           tobacco products by online in-tube solid-phase microextraction coupled
           with liquid chromatography-tandem mass spectrometry
    • Abstract: Publication date: Available online 4 May 2019Source: Analytica Chimica ActaAuthor(s): Atsushi Ishizaki, Hiroyuki Kataoka A simple and sensitive method, using automated online in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), was developed for the determination of four tobacco-specific nitrosamines (TSNAs) in mainstream and sidestream smoke of combustion cigarettes and heated tobacco products. These TSNAs were separated within 4 min on a Capcell Pak C18 MGⅢ column and detected in the positive ion mode by multiple reaction monitoring. The optimum in-tube SPME conditions were 30 draw/eject cycles of 40 μL of sample at a flow rate of 200 μL min−1 using a Supel-Q PLOT capillary column as an extraction device. The extracted TSNAs were easily desorbed from the column by passage of the mobile phase, with no carryover observed. This in-tube SPME LC–MS/MS method showed good linearity for four TSNAs in the 0.5–100 pg mL−1 ranges, with correlation coefficients above 0.9998 (n=24), using stable isotope-labeled TSNAs as internal standards. The validation assays for limit of detection, limit of quantification, specificity, precision and accuracy of the analytes were consistent with the requirements recommended by the ICH guidelines. The validated method was utilized successfully to analyze four TSNAs in mainstream and sidestream smoke samples without any interference peaks. Overall recoveries of TSNAs spiked into smoke sample solutions were 97.3–104.6%. The developed method can automate the extraction, concentration and analysis of samples, and is sensitive and selective for TSNAs. This method was used to analyze TSNAs in mainstream and sidestream smoke samples of several commercially available combustion cigarettes and heated tobacco products.Graphical abstractA simple and sensitive method for the determination of four tobacco-specific nitrosamines in mainstream and sidestream smokes of combustion cigarettes and heated tobacco products was developed by automated online in-tube solid-phase microextraction coupled with liquid chromatography-tandem mass spectrometry.Image 1
  • Nicking Enzyme-Assisted Signal-Amplifiable Hg2+ Detection Using
           Upconversion Nanoparticles
    • Abstract: Publication date: Available online 4 May 2019Source: Analytica Chimica ActaAuthor(s): Anjaly N. Vijayan, Zhiming Liu, Haohan Zhao, Peng Zhang A highly specific and sensitive isothermal method for mercury detection using DNA-conjugated upconversion nanoparticles is reported. A single-stranded DNA containing thymine bases, used as the Hg2+-capturing element utilizing the bond formation of Thymine-Hg2+-Thymine complex, is covalently attached to the NaYF4: Yb3+, Tm3+ nanoparticles. Luminescence resonance energy transfer takes place between the NaYF4: Yb3+, Tm3+ nanoparticles as donor and DNA-intercalating SYBR Green I as the acceptor upon excitation of 980 nm. The sensitivity and selectivity toward Hg2+ are enhanced using the nicking enzyme, Nt. Alwl, which leads to signal amplification. By monitoring the ratio of acceptor emission to a reference peak, the presence of Hg2+ ions are quantitatively determined with a lower detection limit of 0.14 nM, which is much lower than the US Environmental Protection Agency (EPA) limit of Hg2+ in drinking water.Graphical abstractWe report a highly specific and sensitive isothermal method for Hg2+ ion detection using DNA-conjugated upconversion nanoparticles.Image 1
  • A fast progressive spectrum denoising combined with partial least squares
           algorithm and its application in online Fourier transform infrared
           quantitative analysis
    • Abstract: Publication date: Available online 4 May 2019Source: Analytica Chimica ActaAuthor(s): Genwei Zhang, Silong Peng, Shuya Cao, Jiang Zhao, Qiong Xie, Quanjie Han, Yifan Wu, Qibin Huang Fourier transform infrared(FTIR) spectroscopy is an important method in analytical chemistry. A material can be qualitatively and quantitatively analyzed from its FTIR spectrm. Spectrum denoising is commonly performed before online FTIR quantitative analysis. The average method requires a long time to collect spectra, which weakens real-time online analysis. The Savitzky-Golay smoothing method makes peaks smoother with the increase of window width, causing useful information to be lost. The sparse representation method is a common denoising method, that is used to reconstruct spectrum. However, for the randomness of noise, we can’t achieve the sparse representation of noise. Traditional sparse representation algorithms only perform denoising once, and the noise can not be removed completely. FTIR spectrum denoising should therefore be performed in a progressive way. However, it is difficult to determine to what degree of denoising is required. Here, a fast progressive spectrum denoising combined with partial least squares method was developed for online FTIR quantitative analysis. Two real sample data sets were used to test the performance of the proposed method. The experimental results indicated that the progressive spectrum denoising method combined with the partial least squares method performed markedly better than other methods in terms of root mean squared error of prediction and coefficient of determination in the FTIR quantitative analysis.Graphical abstractImage 1
  • Homogeneous liquid-liquid microextraction based on primary amine phase
           separation: a novel approach for sample pretreatment
    • Abstract: Publication date: Available online 4 May 2019Source: Analytica Chimica ActaAuthor(s): Ksenia Cherkashina, Sofya Lebedinets, Aleksei Pochivalov, Aleksey Lezov, Christina Vakh, Andrey Bulatov A homogeneous liquid-liquid microextraction procedure based on primary amine phase separation was developed as a novel approach for the pretreatment of biological fluids. The procedure assumes primary amine dissolution in the aqueous sample phase, resulting in the creation of a homogeneous sample solution followed by phase separation and analyte extraction in the presence of a polar, water-miscible organic solvent. The phenomenon of primary amine phase separation from homogeneous aqueous solution in the presence of a polar, water-miscible organic solvent was studied in detail and applied for separation and preconcentration in chemical analysis for the first time. The suggested approach was used for the HPLC-UV determination of meropenem as a proof-of-concept analyte in human plasma and serum samples. Under optimal conditions, the detector response of meropenem was linear in the concentration range of 0.1-100.0 mg L-1. The limit of detection was calculated from a blank test based on 3σ, was 0.03 mg L-1.
  • Use of physiological information based on grayscale images to improve mass
           spectrometry imaging data analysis from biological tissues
    • Abstract: Publication date: Available online 3 May 2019Source: Analytica Chimica ActaAuthor(s): S. Mas, A. Torro, N. Bec, L. Fernández, G. Erschov, C. Gongora, C. Larroque, P. Martineau, A. de Juan, S. Marco The characterization of cancer tissues by matrix-assisted laser desorption ionization-mass spectrometry images (MALDI-MSI) is of great interest because of the power of MALDI-MS to understand the composition of biological samples and the imaging side that allows for setting spatial boundaries among tissues of different nature based on their compositional differences.In tissue-based cancer research, information on the spatial location of necrotic/tumoral cell populations can be approximately known from grayscale images of the scanned tissue slices. This study proposes as a major novelty the introduction of this physiologically-based information to help in the performance of unmixing methods, oriented to extract the MS signatures and distribution maps of the different tissues present in biological samples. Specifically, the information gathered from grayscale images will be used as a local rank constraint in Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) for the analysis of MALDI-MSI of cancer tissues. The use of this constraint, setting absence of certain kind of tissues only in clear zones of the image, will help to improve the performance of MCR-ALS and to provide a more reliable definition of the chemical MS fingerprint and location of the tissues of interest.The general strategy to address the analysis of MALDI-MSI of cancer tissues will involve the study of the MCR-ALS results and the posterior use of MCR-ALS scores as dimensionality reduction for image segmentation based on K-means clustering. The resolution method will provide the MS signatures and their distribution maps for each tissue in the sample. Then, the resolved distribution maps for each biological component (MCR scores) will be submitted as initial information to K-means clustering for image segmentation to obtain information on the boundaries of the different tissular regions in the samples studied. MCR-ALS prior to K-means not only provides the desired dimensionality reduction, but additionally resolved non-biological signal contributions are not used and the weight given to the different biological components in the segmentation process can be modulated by suitable preprocessing methods.Graphical abstractImage 1
  • Semi-quantification of HIV-1 protease inhibitor concentrations in clinical
           samples of HIV-infected patients using a gold nanoparticle-based
           immunochromatographic assay
    • Abstract: Publication date: Available online 3 May 2019Source: Analytica Chimica ActaAuthor(s): Weeraya Thongkum, Sudarat Hadpech, Yardpiroon Tawon, Tim R. Cressey, Chatchai Tayapiwatana Individual drug concentration data can be a valuable tool for the clinical management of antiretroviral therapy (ART) for the treatment of HIV infection. High performance liquid chromatography (HPLC) based assays are currently the gold standard for drug measurement but its high cost and requirement of technical expertise limits its widespread use. Simpler user-friendly and inexpensive detection assays are needed. A novel immunochromatographic (IC) strip test to detect HIV-1 protease inhibitors (PIs) was fabricated by combining the proteolysis activity of HIV-protease (PR) and an immunochromatographic reaction. The PIs-IC strip cut-off to detect lopinavir (LPV) concentrations was set at 1,000 ng mL-1. We evaluated this novel PIs-IC strip for the semi-quantification of HIV PIs in plasma samples collected from healthy subjects and HIV-infected patients receiving antiretroviral treatment with and without LPV. LPV plasma drug levels were quantified by HPLC and evaluated (blinded to the HPLC results) using the PIs-IC strip. Results of plasma samples tested using the PIs-IC strip were available within 5 min. Using the PIs-IC strip test the accuracy, specificity and sensitivity were 97.8%, 97.1 %, and 100%, respectively, compare to the gold-standard assay, to detect LPV in human plasma samples. This novel PIs-IC strip test could be used as a simple tool for the rapid monitoring of PIs levels in HIV-infected patients, although further clinical evaluation is needed.Graphical abstractImage 1
  • Nanotoxicity assessment: a challenging application for cutting edge
           electroanalytical tools
    • Abstract: Publication date: Available online 2 May 2019Source: Analytica Chimica ActaAuthor(s): Francesca Bettazzi, Ilaria Palchetti In the recent years, the number of commercial products containing engineered nanomaterials (ENMs) has increased exponentially. Consequently, the toxicological profile of ENMs on the ecosystems as well as on human health has to be carefully evaluated. Nanotoxicology, an interdisciplinary research area devoted to assessing the hazards associated with ENMs, is expanding rapidly. Many physicochemical techniques and biochemical methodologies have been proposed and are currently used to characterize nanomaterials from a toxicological point of view. Electroanalytical and bioelectrochemical methods can be useful in expanding the repertoire of accessible nanotoxicity-assessment technologies and to accelerate the testing and screening of the toxicological effects of ENMs. These methods can be used for elucidating the toxicological behavior of ENMs at single cell, cell population and whole-organism levels, for in vitro and in vivo measurements, respectively. The aim of this review is to provide an overview on the bioelectrochemical approaches that have been proposed for ENMs toxicity assessment. Furthermore, an overview on cutting-edge electroanalytical devices with a potential impact to this peculiar application is provided.Graphical abstractImage 1
  • Regioselectively substituted cellulose mixed esters synthesized by
           two-steps route to understand chiral recognition mechanism and fabricate
           high-performance chiral stationary phases
    • Abstract: Publication date: Available online 1 May 2019Source: Analytica Chimica ActaAuthor(s): Chunchun Yin, Jinming Zhang, Limin Chang, Mei Zhang, Tiantian Yang, Xiaocheng Zhang, Jun Zhang It is challenging to design and fabricate new and high-performance cellulose-based chiral stationary phases (CSPs), due to the indistinct chiral recognition mechanism and the inherent difficulty to control the structure of cellulose derivatives. Herein, taking advantage of the high regioselective benzoylation of cellulose in 1-allyl-3-methylimidazolium chloride, a series of regioselectively substituted cellulose mixed esters, cellulose 6-benzoate-2,3-phenylcarbamate, are directly obtained by a facile two-steps route without protecting and deprotecting process. The resultant cellulose mixed esters exhibit high chiral recognition capability. In particular, when the benzoate group has an electron-donating substituent on phenyl ring, such as 4-tert-butyl group, the corresponding regioselectively substituted cellulose mixed esters have much better enantioseparation capability than cellulose tri(3,5-dimethylphenylcarbamate), which is commercially available as Chiralcel OD column, one of the most powerful CSPs. More importantly, via adjusting the chemical structure of cellulose derivatives and adding a post-treatment process to optimize their chiral recognition properties, the chiral recognition mechanism is clearly revealed. The synergy of the hydrophobic helical conformation, weak hydrogen-bond donating ability and appropriate distribution of substituents of cellulose derivatives is essential to fabricate high-performance CSPs.Graphical abstractRegioselectively substituted cellulose mixed esters with super chiral separation capability are directly synthesized by a facile two-steps process. The synergism of the hydrophobic helical conformation, weak hydrogen-bond donating ability and appropriate distribution of substituents in cellulose derivatives is essential to the enantioseparation.Image 1
  • Investigation of lipidomic perturbations in oxidatively stressed
           subcellular organelles and exosomes by asymmetrical flow field–flow
           fractionation and nanoflow ultrahigh performance liquid
           chromatography–tandem mass spectrometry
    • Abstract: Publication date: Available online 1 May 2019Source: Analytica Chimica ActaAuthor(s): Joon Seon Yang, Jin Yong Kim, Jong Cheol Lee, Myeong Hee Moon We investigated the effect of oxidative stress (OS) on lipidomic perturbations in the subcellular fractions and exosomes of human embryonic kidney (HEK) 293 cells using asymmetrical flow field–flow fractionation (AF4) and nanoflow ultrahigh performance liquid chromatography–electrospray ionization–tandem mass spectrometry (nUHPLC-ESI-MS/MS). We treated HEK 293 cells with hydrogen peroxide (H2O2) and fractionated the cell lysates using AF4 to determine the change in size and population of the subcellular fractions and exosomes, and to obtain narrow size fractions for lipid analysis. A total of 438 lipids from 642 identified species—including oxidized lipids—were quantified. The relative amount of secreted exosomes increased by 28% during OS, whereas the amount of subcellular species decreased by 35%. There was a significant increase in the level of oxidized phospholipids in the mitochondrion-enriched subcellular fractions, but not in the exosomes. Most high-abundance triacylglycerol (TG) species increased in the stressed cells, whereas they decreased in the exosomes. During OS, ceramides involved in the apoptotic mitochondrial pathway were accumulated in the subcellular fractions, whereas their levels were unaffected in the exosomes. The present study demonstrated that AF4 and nUHPLC-ESI-MS/MS can be used to investigate lipid alterations in subcellular and extracellular species during OS, and the pathological relationships in diseases caused by reactive oxygen species.Graphical abstractImage 1
  • Nanolitre-scale cell based on L-shaped silica capillary and optical fibre
           for absorption photometric detection in capillary liquid chromatography
    • Abstract: Publication date: Available online 1 May 2019Source: Analytica Chimica ActaAuthor(s): Jozef Šesták, Josef Planeta, Vladislav Kahle Miniaturised photometric detection cell based on the 150 μm I. D. L-shaped fused silica capillary (L-cell) and silica optical fibre is discussed in this paper. Light enters the cell via right angle bend and transmitted light is collected by silica optical fibre inserted into the capillary outlet. Ray trace analysis reveals that L-cell geometry works as a waveguide and effectively eliminates parasitic light, which is guided by the wall of any fused silica capillary cell. Low total level of stray light is further documented by measurement of absorbance of acetone-water mixture at 266 nm with the observed upper limit of dynamic range 2.2 AU. 3-mm L-cell has a volume of 53 nL and exhibits effective optical path 2.7 mm. Cell variance determined in the flow rate range 1-10 μL·min-1 indicates, that 3-mm L-cell is optimal for use with 200 - 300 μm I. D. capillary columns. Furthermore, isocratic separation of alkylbenzenes mixture at 0.5 μL·min-1 demonstrates effective use of 0.5-mm L-cell (8.8 nL) and possible performance of longer L-cells with high efficiency 100 μm I. D. capillary column.Graphical abstractImage 1
  • Preparation of Silver Nanoparticles Coated ZnO/Fe3O4 Composites Using
           Chemical Reduction Method for Sensitive Detection of Uric Acid via
           Surface-enhanced Raman Spectroscopy
    • Abstract: Publication date: Available online 30 April 2019Source: Analytica Chimica ActaAuthor(s): Melisew Tadele Alula, Lemmens, Liu Bo, Dirk Wulferding, Jyisy Yang, Hendrik Spende In this study, silver nanostructures decorated magnetic nanoparticles for surface-enhanced Raman scattering (SERS) measurements were prepared via heat induced catalytic activity of ZnO nanostructures. The ZnO/Fe3O4 composite was first prepared by dispersing pre-formed magnetic nanoparticles into alkaline zinc nitrate solutions. After annealing of the precipitates, the formed ZnO/Fe3O4 composites were successfully decorated with silver nanostructures by dispersing the composites into silver nitrate/ethylene glycol solution at 95 oC in water bath. To find the optimal condition when preparing Ag/ZnO/Fe3O4 composites for SERS measurements, factors such as reaction time and concentration of silver nitrate were studied. Results indicated that the formation of silver nanoparticles (AgNPs) on ZnO/Fe3O4 was significantly improved with the assistance of ZnO. The concentration of silver nitrate and reaction time affected the morphologies and sizes of the formed composites and optimal condition in preparation of the composites for SERS measurement was found using 100 mM of silver nitrate with a reaction time of 20 min. Under optimized conditions, the obtained SERS intensities were highly reproducible. The substrates were applied for quantitative analysis of uric acid in aqueous solution and a linear response for concentrations up to 10 μM was obtained. Successful application of these prepared composites to determine uric acid in urine sample without any pretreatment of the urine sample was done.Graphical abstractImage 1
  • Significant role of supercritical fluid chromatography - mass spectrometry
           in improving the matrix effect and analytical efficiency during
           multi-pesticides residue analysis of complex chrysanthemum samples
    • Abstract: Publication date: Available online 29 April 2019Source: Analytica Chimica ActaAuthor(s): Shaochi Wang, Peipei Qi, Shanshan Di, Jiao Wang, Shengan Wu, Xiangyun Wang, Zhiwei Wang, Qiang Wang, Xinquan Wang, Changshan Zhao, Qiang Li As an important “food and drug dual-use” product, chrysanthemums are widely used in both botanical medicine and food applications. However, the misuse of pesticides during chrysanthemum cultivation makes pesticide residue monitoring crucial. The aim of the present work was to address this practical demand for the simultaneous determination of multiple pesticide residues in various species of chrysanthemums. Both the sample pre-treatment and instrumental methods were systematically investigated. Seven chrysanthemum samples were extracted using acetonitrile and purified by dispersive solid-phase extraction with amino-modified multi-walled carbon nanotubes (MWCNTs-NH2) and C18 as the cleanup co-adsorbents. After optimizing the amounts of MWCNTs-NH2 and C18, matrix effects could not be avoided during LC-MS/MS analysis of 112 pesticides, although satisfactory recoveries were obtained. The use of SFC-MS/MS was evaluated, which demonstrated the significant positive role of SFC-MS/MS in reducing the matrix effects during pesticide residue analysis. In addition, the use of SFC-MS/MS permitted a shorter run time and afforded greater analytical efficiency. Method validation was further performed to evaluate the linearity, sensitivity, recovery, and precision of the developed method. Good linearity was observed for 92% of the analytes in the concentration range of 2–250 μg L−1 for all seven of the chrysanthemum samples. The LODs of the 112 pesticides ranged from 0.01 to 31.41 μg L−1, depending on the sample, while the mean recoveries of all of the spiked pesticides ranged from 81.8% to 102% for concentrations of 20, 50, and 200 μg kg−1. These results clearly demonstrate the applicability of the developed method for the simultaneous determination of multi-pesticides in various chrysanthemum samples.Graphical abstractImage 1
  • M13 Phage as Network Frame for the Quantification of Pb2+ based on the
           Pb2+-Induced in-situ Growth of Gold Nanoparticles
    • Abstract: Publication date: Available online 29 April 2019Source: Analytica Chimica ActaAuthor(s): Xiao-Yan Wang, Ting Yang, Si-Yi Wang, Kai-Dong Du, Ming-Li Chen, Jian-Hua Wang Routine detection of Pb2+ is of great importance to environmental monitoring because of its deleterious effects on human health and environment. In this work, an easy-to-operate method for the one-step detection of Pb2+ was developed based on the phage-Pb2+ interactions and their influence on the surface plasmon resonance (SPR) absorption band of AuNPs. AuNPs grow in-situ on the surface of M13 phages and the resulting phage-AuNP networks were directly used for lead sensing. The addition of Pb2+ facilitates further growth of the parent AuNPs and results in a blue shift of the SPR absorption peak. By integrating AuNPs preparation and sensing procedure into one step, a simplified Pb2+ detection approach was developed with improved sensitivity and shortened analysis time. By quantifying A528 with UV-vis spectrometer, a linear range of 0.5-5.0 μmol L-1 together with a limit of detection of 45 nmol L-1 was obtained. The one-step approach avoided complicated AuNPs preparation and functionalization process, and got rid of the unstable problems of AuNPs for long-term preservation, offering simple and cost-effective Pb2+ detection method for resource-poor settings.Graphical abstractImage 1
  • Graphene oxide as an efficient adsorbent of solid-phase extraction for
           online preconcentration of inorganic and organic mercurials in freshwater
           followed by HPLC-ICP-MS determination
    • Abstract: Publication date: Available online 29 April 2019Source: Analytica Chimica ActaAuthor(s): Shiwei Yang, Danyu Zhang, Heyong Cheng, Yuanchao Wang, Jinhua Liu For the past several decades, lots of adsorbent nanomaterials have been adopted for the enrichment of mercuric compounds. In this paper, graphene oxide bounded with silica particles were employed as the absorbent for online preconcentration of Hg(II), methylmercury (MeHg) and ethylmercury (EtHg) by solid phase extraction. The adsorbent offered satisfactory adsorption capacities of 40.7 for Hg(II), 91.4 for MeHg and 103.8 mg g-1 for EtHg. Enrichment conditions such as type, concentration and volume of conditioning and eluting reagents were optimized. The pH, volume and flow rate of sample were also optimized. High enrichment factors (1963, 1881 and 1794 for Hg(II), MeHg and EtHg, respectively) were obtained with 10 mL sample (adjusted to pH 4-7) at 10 mL min-1 flow rate, 5 μL of 10 mM benzoic acid for elution and 4 mL of 1 mM 4-phenyl-3-aminothiourea for preconditioning. The detection limits obtained were downscaled to be 0.005 for Hg(II), 0.006 for MeHg and 0.009 ng L-1 for EtHg with relative standard deviations of all the analytes below 5%. Standard reference material and spiked water samples were analyzed for validating the method with satisfactory recoveries of 89-106%. The present method was successfully applied to determine mercury compounds in drinking water, and river and tap water, in which Hg(II), MeHg and EtHg were presented below the China’s drinking standard limit of 1 μg L-1.Graphical abstractImage 1
  • Bifunctional S, N-Codoped Carbon Dots-Based Novel Electrochemiluminescent
           Bioassay for Ultrasensitive Detection of Atrazine using Activated
           Mesoporous Biocarbon as Enzyme Nanocarriers
    • Abstract: Publication date: Available online 29 April 2019Source: Analytica Chimica ActaAuthor(s): YunqingWu, Yuxin Chen, Shiqin Zhang, Lizhi Zhang, Jingming Gong A novel and ultrasensitive electrochemiluminescent (ECL) bioassay has been developed for the detection of atrazine (ATZ), whereby bifunctional S, N-codoped carbon dots (S, N-CDs) and activated mesoporous bicarbons (BCs) have been innovatively integrated to synergistically amplify the ECL signal. When endogenous dissolved O2 is used as a coreactant, its sluggish reduction hinders the enhancement of ECL intensity of the luminophore, thus restricting its further application in bioanalysis. Here, bifunctional S, N-CDs severe as not only the ECL luminophore but the coreaction accelerator of dissolved O2 to generate more intermediates to boost the coreaction without using any other coreactant and coreaction accelerator. The as-formed nanoarchitectures of BCs possess enlarged surface area as the nanocarriers. They could provide adequate active sites for immobilization of tyrosinase (Tyr), which greatly prompts the ECL bioassay applications. Such a smart integration of bifunctional S, N-CDs, activated mesoporous BCs and the enzyme inhibition reaction achieves a unique and attractive high-performance signal-on ECL bioassay, realizing ultrasensitive detection of ATZ. Under the optimal condition, this bioassay exhibits two linear ranges, from 0.0001 to 0.01 μg L−1 and 0.01−20 μg L−1 with a detection limit of 0.08 ng L−1 at signal to noise ratio of 3. The as-fabricated assay is sensitive and economical, opening a new way for the enhancement of ECL signal output and a versatile strategy for ultrasensitive ECL bioanalysis.Graphical abstractImage 1
  • Magnetic graphitic carbon nitride nano-composite for ultrasound-assisted
           dispersive micro-solid-phase extraction of Hg(II) prior to quantitation by
           atomic fluorescence spectroscopy
    • Abstract: Publication date: Available online 29 April 2019Source: Analytica Chimica ActaAuthor(s): Meng-ting Shi, Xin-an Yang, Wang-bing Zhang A nanosheet structure of Fe3O4/g-C3N4 magnetic composite has been prepared and utilized as adsorbent for the ultrasound-assisted dispersive magnetic micro-solid-phase extraction of the ultra-trace inorganic mercury [Hg(II)]. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Fouries transform infrared spectroscopy images manifested that the hydrothermal systhesis promoted the binding of Fe3O4 particles with g-C3N4. The enrichment performance of composites depended on their compositions, and the recovery of Hg(II) on C-m30 (with Fe3O4/g-C3N4 mass ratio 2:3) was higher than that on other ratios. Recorded data showed that ultrasound wave was an effective method for reducing the agglomeration of magnetic materials and enhancing their adsorption properties. The Hg signal obtained by 80% power input is 3.2 times stronger than the signal by strring mode. X-ray diffraction characterization of the recovered adsorbent showed that g-C3N4 needed to be updated after repeated use for four times. In addition, competitive adsorption may be main factor affecting the inhibitory effect of high concentration methylmercury on inorganic mercury. Under the optimized conditions, the detection limit of the proposed method was 1.4 ng L-1 and relative standard deviation of 4.6% for 0.05 μg L-1 Hg(II) was obtained. The linear calibration range was 0.005-0.4 μg L-1. The accuracy of the method was verified through analysis of the certificated reference materials. The proposed method has been applied in the determination of inorganic Hg in natural water samples.Graphical abstractImage 1
  • High-resolution imaging and single-cell analysis via laser
           ablation-inductively coupled plasma-mass spectrometry for the
           determination of membranous receptor expression levels in breast cancer
           cell lines using receptor-specific hybrid tracers
    • Abstract: Publication date: Available online 29 April 2019Source: Analytica Chimica ActaAuthor(s): Thibaut Van Acker, Tessa Buckle, Stijn J.M. Van Malderen, Danny M. van Willigen, Vincent van Unen, Fijs W.B. van Leeuwen, Frank Vanhaecke This work evaluates the possibility of placement of high-resolution imaging and single-cell analysis via laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) within precision medicine by assessing the suitability of LA-ICP-MS as a micro-analytical technique for the localization and quantification of membranous receptors in heterogeneous cell samples that express both the membrane-bound receptors C-X-C chemokine receptor type 4 (CXCR4) and epidermal growth factor receptor (EGFR). Staining of the breast cancer cell lines MDA-MB-231 X4 and MDA-MB-468 was achieved using receptor-specific hybrid tracers, containing both a fluorophore and a DTPA single-lanthanide chelate. Prior to LA-ICP-MS imaging, fluorescence confocal microscopy (FCM) imaging was performed to localize the receptors, hereby enabling direct comparison. Based on the different expression levels of CXCR4 and EGFR, a distinction could be made between the cell lines using both imaging modalities. Furthermore, FCM and LA-ICP-MS demonstrated complementary characteristics, as a more distinct discrimination could be made between both cell lines based on the EGFR-targeting hybrid tracer via LA-ICP-MS, due to the intrinsic CXCR4-related green fluorescent protein (GFP) signal present in the MDA-MB-231 X4 cells. Employing state-of-the-art LA-ICP-MS instrumentation in bidirectional area scanning mode for sub-cellular imaging of MDA-MB-231 X4 cells enabled the specific binding of the CXCR4-targeting hybrid tracer to the cell membrane to be clearly demonstrated. The stretching of cells over the glass substrate led to a considerably higher signal response for pixels at the cell edges, relative to the more central pixels. The determination of the expression levels of CXCR4 and EGFR for the MDA-MB-468 cell line was performed using LA-ICP-MS single-cell analysis (sc-LA-ICP-MS) and external calibration, based on the quantitative ablation of Ho-spiked dried gelatin droplet standards. Additionally, a second calibration approach was applied based on spot ablation of highly homogeneous dried gelatin gels in combination with the determination of the ablated volume using atomic force microscopy (AFM) and yielded results which were in good agreement with the expression levels determined via flow cytometry (FC) and mass cytometry (MC). Hybrid tracers enable a direct comparison between (i) FCM and LA-ICP-MS imaging for the evaluation of the microscopic binding pattern and between (ii) FC, MC and sc-LA-ICP-MS for the quantification of receptor expression levels in single cells.Graphical abstractImage 1
  • Linkage and sequence analysis of neutral oligosaccharides by negative-ion
           MALDI tandem mass spectrometry with laser-induced dissociation
    • Abstract: Publication date: Available online 29 April 2019Source: Analytica Chimica ActaAuthor(s): Chuncui Huang, Jingyu Yan, Lingpeng Zhan, Min Zhao, Jinyu Zhou, Huanyu Gao, Wenchun Xie, Yan Li, Wengang Chai Mass spectrometry (MS) has become the primary method for high-sensitivity structural determination of oligosaccharides. Fragmentation in the negative-ion MS can provide a wealth of structural information and these can be used for sequence determination. However, although negative-ion MS of neutral oligosaccharide using the deprotonated molecule [M−H]− as the precursor has been very successful for electrospray ionization (ESI), it has only limited success for matrix-assisted laser desorption/ionization (MALDI). In the present study, the features of negative-ion MALDI primary spectra were investigated in detail and the product-ion spectra using [M−H]– and [M+Cl]– as the precursors were carefully compared. The formation of [M−H]– was the main difficulty for MALDI while [M+Cl]– was proved to be useful as alternative precursor anion for MALDI-MS/MS to produce similar fragmentation for sequencing of neutral oligosaccharides. N-(1-naphthyl)ethylenediamine dihydrochloride was then used as both the matrix and the Cl– dopant to evaluate the extent of structural information that can be obtained by negative-ion fragmentation from [M+Cl]– using laser-induced dissociation (LID)-MS/MS for linkage assignment of gluco-oligosaccharides and for typing of blood-group ABO(H) and Lewis antigens on either type 1 or type 2 backbone-chains.Graphical abstractImage 1
  • A novel on-flow mass spectrometry-based dual enzyme assay
    • Abstract: Publication date: Available online 26 April 2019Source: Analytica Chimica ActaAuthor(s): Claudia Seidl, Adriana Ferreira Lopes Vilela, Juliana Maria Lima, Gabriel Mazzi Leme, Carmen Lúcia Cardoso This work describes a new simultaneous on-flow dual parallel enzyme assay based on immobilized enzyme reactors (ICERs) with mass spectrometry detection. The novelty of this work relies on the fact that two different enzymes can be screened at the same time with only one single sample injection and in less than 6 min. The system consisted of two immobilized capillary enzyme reactors (ICERs). More specifically, the ICERs comprised two different enzymes that were accommodated in parallel and were placed between a liquid chromatography (LC) system and a mass spectrometer (MS). The resulting system could be adapted to other types of enzyme reactors with different supports. All the elements in the system were interfaced by means of two 10-port/two-position switching valves. Different tubing dimensions allowed us to monitor the activity of each enzyme independently during the same analysis. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) bioreactors were chosen as proof of concept. Acetylcholine (ACh) was used as substrate; the area of its protonated enzymatic hydrolysis product ion, choline, [M+H]+ m/z 104.0, was monitored in the presence and absence of the standard cholinesterase inhibitor galantamine. This method proved to be an interesting tool for fast, simultaneous, and independent label-free dual enzyme inhibitor assay.Graphical abstractImage 1
  • Fine-scale in-situ measurement of lead ions in coastal sediment pore water
           based on an all-solid-state potentiometric microsensor
    • Abstract: Publication date: Available online 26 April 2019Source: Analytica Chimica ActaAuthor(s): Guangtao Zhao, Jiawang Ding, Wei Qin Methods for in-situ measurements of heavy metal ions in coastal sediment pore water to elucidate fine-scale biogeochemical and environmental processes are highly required but have rarely been reported. In this work, an all-solid-state lead-selective microelectrode (Pb2+-ISμE) based on a poly(3,4-ethylenedioxythiophene)-poly(sodium 4-styrenesulfonate) (PEDOT/PSS) modified gold wire with a diameter of 14 μm has been fabricated. The proposed Pb2+-ISμE is capable of in-situ measurement of Pb2+ in coastal sediment pore water at millimeter depth intervals. The Pb2+-ISμE shows a Nernstian response for Pb2+ within the activity range of 2.1 × 10-9-2.1 × 10-4 M (S = 28.1 ± 1.3 mV/dec, R2 = 0.998) in 0.5 M NaCl, and the detection limit is 6.4 × 10-10 M. By lowering the microelectrode into a coastal sediment core with a micro-manipulator, the proposed Pb2+-ISμE allows the direct measurement of the vertical distribution profile of Pb2+ in the pore water. The in-situ measurement of Pb2+ using the microsensor could avoid the problems of sample handling. Moreover, the detection system can be extended to assess the vertical distribution profiles of other heavy metal ions in sediment pore water by using different ion-selective microelectrodes.Graphical abstractAn all-solid-state lead-selective microelectrode was fabricated for fine-scale in-situ measurements of Pb2+ in sediment pore water.Image 1
  • Label-free counting of Escherichia coli cells in nanoliter droplets using
           3D printed microfluidic devices with integrated contactless conductivity
    • Abstract: Publication date: Available online 26 April 2019Source: Analytica Chimica ActaAuthor(s): Lucas C. Duarte, Federico Figueredo, Luiz E.B. Ribeiro, Eduardo Cortón, Wendell K.T. Coltro This study describes for the first time the development of 3D printed microfluidic devices with integrated electrodes for label-free counting of E. coli cells incorporated inside droplets based on capacitively coupled contactless conductivity detection (C4D). Microfluidic devices were fully fabricated by 3D printing in the T-junction shape containing two channels for disperse and continuous phases and two sensing electrodes for C4D measurements. The disperse phase containing E. coli K12 cells and the continuous phase containing oil and 1% Span® 80 were pumped through flow rates fixed at 5 and 60 μL min-1, respectively. The droplets with incorporated cells were monitored in the C4D system applying a 500-kHz sinusoidal wave with 1 Vpp amplitude. The generated droplets exhibited a spherical shape with average diameter of 321 ± 9 μm and presented volume of 17.3 ± 0.5 nL. The proposed approach demonstrated ability to detect E. coli cells in the concentration range between 86.5 and 8650 CFU droplet-1. The number of cells per droplet was quantified through the plate counting method and revealed a good agreement with the Poisson distribution. The limit of detection achieved for counting E. coli cells was 63.66 CFU droplet-1. The label-free counting method has offered instrumental simplicity, low cost, high sensitivity and compatibility to be integrated on single microfluidic platforms entirely fabricated by 3D printing, thus opening new possibilities of applications in microbiology.Graphical abstractImage 1
  • Electrochemical co-deposition synthesis of Au-ZrO2-graphene nanocomposite
           for a nonenzymatic methyl parathion sensor
    • Abstract: Publication date: Available online 25 April 2019Source: Analytica Chimica ActaAuthor(s): Nan Gao, Chaohui He, Mingyu Ma, Zhiwei Cai, Yang Zhou, Gang Chang, Xianbao Wang, Yunbin He For the first time, a simple electrochemical co-deposition was utilized to synthesis the gold and zirconia nanocomposites modified graphene nanosheets on glassy carbon electrode (Au-ZrO2-GNs/GCE) for electrocatalytic analysis of methyl parathion (MP). According to Field-Emission Scanning Electron Microscopy (FE-SEM), Transmission Electronic Microscopy (TEM) and X-Ray Diffraction (XRD), the gold nanoparticles were uniformly distributed on the surface of graphene-based nanocomposite. The Au-ZrO2-GNs/GCE based sensor exhibited superior capacity for MP detection, ascribed to the strong affinity of zirconia towards the phosphoric group, as well as the high catalytic activity and good conductivity of Au-GNs. The best fabrication and work conditions were then obtained by systematically optimization of the electrodeposition process, pH value and enrichment time. Compared to the gold nanoparticles, zirconia or graphene modified electrodes, Au-ZrO2-GNs/GCE sensor displayed superior electro-catalytic response toward MP oxidation. The sensor response current of square wave voltammetry was highly linearly correlated with the MP concentrations range of 1-100 ng mL-1 and 100-2400 ng mL-1 with the detection limit of 1 ng mL-1. The Au-ZrO2-GNs/GCE nanocomposite sensor showed excellent accuracy and reproducibility for detection of MP in Chinese cabbage samples, providing a new method for efficient pesticide detection in practical applications.Graphical abstractImage 1
  • Hypersensitive electrochemical immunoassays based on highly N-doped
           silicon carbide (SiC) electrode
    • Abstract: Publication date: Available online 25 April 2019Source: Analytica Chimica ActaAuthor(s): Jun-Hee Park, Zhiquan Song, Ga-Yeon Lee, Sung-Min Jeong, Min-Jung Kang, Jae-Chul Pyun Highly N-doped SiC was presented as an optimal electrode for electrochemical immunoassays with a far higher sensitivity than chemiluminescence detection. As the first step, the electrochemical properties of highly N-doped SiC, such as the double-layer capacitance (Cdl), rate constant for electron transfer (kapp) and ideal polarizable potential range (electrochemical window) were analyzed and compared with those of Au, Pt, and graphite electrodes. The highly N-doped SiC electrode was used for the quantification of oxidized 3,3’,5,5’-tetramethylbenzidine (TMB) which was widely used as chromogenic substrate for commercialized immunoassay kits. In order to enhance the sensitivity for the quantification of the oxidized TMB the chronoamperometry was applied to avoid the background current of i-V measurement. Finally, the chronoamperometry based on the highly N-doped SiC electrode was applied to commercial immunoassay kits for the medical diagnosis of the human immunodeficiency virus (HIV) and the human hepatitis B surface antigen (hHBsAg). The chronoamperometric measurement based on the highly N-doped SiC electrode was proved to detect at far lower limits in comparison with the conventional optical density measurement as well as the chemiluminescence assay based on luminol as a chemiluminescent probe.Graphical abstractImage 1
  • A morphology-based ultrasensitive multicolor colorimetric assay for
           detection of blood glucose by enzymatic etching of plasmonic gold
    • Abstract: Publication date: Available online 25 April 2019Source: Analytica Chimica ActaAuthor(s): Shenghao Xu, Liping Jiang, Yuanyuan Liu, Pingping Liu, Wei Wang, Xiliang Luo An ultrasensitively multicolor colorimetric assay on the basis of enzyme-catalyzed reaction mediated etching of gold nanobipyramids (Au NBPs) is developed for detection of blood glucose with naked eye. This assay depends on the catalytic oxidation of H2O2 (generated from glucose oxidation) by horseradish peroxidase (HRP) to generate hydroxyl radicals (•OH) with strong oxidizability, which can accelerate the Au NBPs etching and accompany with vivid color changes and localized surface plasmon resonance (LSPR) blue shift. On the basis of this, the proposed colorimetric glucose assay accomplishes a dynamic range of 0.05 to 90 μM with detection limit of 0.02 μM, which is almost three orders of magnitude lower than that (10 μM) based on gold nanorods (Au NRs). Moreover, the approximate glucose levels can be intuitively and conveniently judged by the color changes with naked eye. Most importantly, visually distinguish between healthy people and diabetic patients by naked eye dispense with any sophisticated instrument is the most important highlight of this colorimetric assay, indicating the available potential for diagnosis. To the best of our knowledge, this is the first report of colorimetric assay using Au NBPs as etching substrates for visually analysis of glucose.Graphical abstractAn ultrasensitively multicolor colorimetric assay based on enzyme-catalyzed reaction mediated etching of gold nanobipyramids (Au NBPs) is developed for blood glucose assay.Image 1
  • Heterogeneity analysis of polymeric carboxylic acid functionality by
           selective derivatization followed by size exclusion chromatography
    • Abstract: Publication date: Available online 25 April 2019Source: Analytica Chimica ActaAuthor(s): T. Brooijmans, R.A. Okhuijsen, G.M.M. Oerlemans, B.W.J. Pirok, P.J. Schoenmakers, R.A.H. Peters Waterborne polymers are increasingly applied in our society, replacing traditional solvent-borne coatings and thus reducing environmental impact of coatings. The majority of waterborne dispersions are stabilized by the incorporation of neutralizable carboxylic acid functionality. The characterization of synthetic waterborne polymer systems can be performed by a wide variety of chromatographic and spectroscopic techniques. However, none of these approaches is able to determine the acid functionality distribution over the molecular-weight distribution directly. In this research, an innovative approach is developed which enables this analysis. The approach is based on the specific and complete derivatization of carboxylic acid functionality with phenacylbromide.Size exclusion chromatography (SEC) analysis of the derivatized polymers is performed followed by ultraviolet- (UV) and refractive index (RI) detection, enabling the quantitative determination of the acid content per molecular weight fraction. The applicability of the developed protocol is shown for various polymer systems.Graphical abstractImage 1
  • Amoxicillin on polyglutamic acid composite three-dimensional graphene
           modified electrode: reaction mechanism of amoxicillin insights by
           computational simulations
    • Abstract: Publication date: Available online 25 April 2019Source: Analytica Chimica ActaAuthor(s): Chenglong Chen, Xuchu Lv, Wu Lei, Yi Wu, Shasha Feng, Yong Ding, Jingjing Lv, Qingli Hao, Shen-Ming Chen An electrochemical sensor based on a glassy carbon electrode (GCE) modified by three-dimensional graphene (3D-GE) and polyglutamic acid (PGA) was developed to quantitatively detect Amoxicillin (AMX), a worldwide used antibiotic. AMX response at PGA/3D-GE/GCE involving the transfer of one electron and an equal number of protons were determined using electrochemical approaches. Density functional theory simulations were performed to give insights on the reaction mechanism of AMX on the surface of the modified electrode. When the optimization of the experimental conditions was completed, the linear range of AMX was 2-60 μM. Besides, the detection limit was calculated as 0.118 μM (S/N = 3). And the modified electrode could detect the concentration of the AMX in human urine samples. Overall, the developed PGA/3D-GE/GCE for determination of AMX shows great potentials in practice.Graphical abstractImage 1
  • A Simple Paper-based Aptasensor for Ultrasensitive Detection of Lead (II)
    • Abstract: Publication date: Available online 24 April 2019Source: Analytica Chimica ActaAuthor(s): Zahra Khoshbin, Mohammad Reza Housaindokht, Mohammad Izadyar, Asma Verdian, Mohammad Reza Bozorgmehr In this study, a simple paper-based aptasensor has been developed for the ultrasensitive detection of lead (Pb2+) ion within about 10 minutes. The aptasensor has been successfully designed by taking advantages of the Förster Resonance Energy Transfer (FRET) process and the super fluorescence quenching property of graphene oxide (GO) sheet. The sensing mechanism of the aptasensor is based on the conformational switch of the Pb2+-specific aptamer from a random coil to a G-quadruplex structure. An injection of Pb2+ on the paper-based platform induces the release of the specific aptamer from the GO surface that recovers the fluorescence emission. Under the optimal experimental conditions, there is a good linear relationship between the fluorescence recovery and the Pb2+concentration in the ranges of 5-70 pM and 0.07-20 nM. Moreover, the aptasensing array exhibits a high sensitivity to Pb2+ with an ultra-low detection limit of 0.5 pM. The developed aptasensor has been successfully applied to determine Pb2+ in tap water, lake water, milk, and human blood serum. The paper-based aptasensor can be efficiently utilized to detect other metal ions and biological molecules by substituting target specific aptamer.Graphical abstractImage 1
  • Recent advances of boronate affinity materials in sample preparation
    • Abstract: Publication date: Available online 24 April 2019Source: Analytica Chimica ActaAuthor(s): Yang Chen, Ailan Huang, Yanan Zhang, Zijun Bie Boronate affinity materials, as widely used sorbents for the enrichment of cis-diol-containing molecules, have been rapidly developed and increasingly utilized for various applications in recent years. cis-Diol-containing molecules, including saccharides, nucleosides, catecholamines, glycans and glycoproteins/glycopeptides, are major targets in the frontiers of many research areas, such as environmental analysis, the food industry and bioanalysis. As the analysis of these molecules usually suffers from the low abundance of targets and the high abundance of interference, selective enrichment is a fundamental step of sample preparation before analysis. In this review, we survey recent achievements of boronate affinity materials and their applications in sample preparation. We mainly focus on the fundamental considerations of materials as well as important applications in the past 3 years. Particularly, the effects of the substrate structure on the performance of boronate affinity materials, such as binding capacity, affinity, selectivity and working pH, will be discussed. Furthermore, the applications in sample preparation will also be introduced, with a main emphasis on what merits can be provided by boronate affinity materials to overcome the challenges in sample preparation.Graphical abstractImage 1
  • Targeted and non-targeted forensic profiling of black powder substitutes
           and gunshot residue using gradient ion chromatography – high resolution
           mass spectrometry (IC-HRMS)
    • Abstract: Publication date: Available online 24 April 2019Source: Analytica Chimica ActaAuthor(s): Matteo D. Gallidabino, Rachel C. Irlam, Michael C. Salt, Michael O’Donnell, Matthew S. Beardah, Leon P. Barron A novel and simplified gradient IC-HRMS approach is presented in this work for forensic profiling of ionic energetic material residues, including low-order explosives and gunshot residue (GSR). This new method incorporated ethanolic eluents to facilitate direct coupling of IC and HRMS without auxiliary post-column infusion pumps that are traditionally used to assist with gas phase transfer. Ethanolic eluents also enabled better integration with an in-service protocol for direct analysis of high-order organic explosives by IC-HRMS, without requiring solvent exchange before injection. Excellent method performance was achieved, enabling both full scan qualitative and quantitative analysis, as required. In particular, linearity for 19 targeted compounds yielded R2> 0.99 across several orders of magnitude, with trace analysis possible at the low-mid pg level. Reproducibility and mass accuracies were also excellent, with peak area %RSDs < 10 %, tR %RSDs < 0.4% and δm/z < 3 ppm. The method was applied to targeted analysis of latent fingermarks and swabbed hand sweat samples to determine contact with a black-powder substitute containing nitrate, benzoate and perchlorate. When combined with principal component analysis (PCA), the effect of time since handling on recorded signals could be interpreted further in order to support forensic investigations. In a second, non-targeted application, PCA using full scan IC-HRMS data enabled classification of GSR from three different types of ammunition. An additional 20 markers of GSR were tentatively identified in silico, in addition to the 15 anions detected during targeted analysis. This new approach therefore streamlines and adds consistency and flexibility to forensic analysis of ionic energetic material. Furthermore, it also has implications for targeted, non-targeted and suspect screening applications in other fields by expanding the separation space to low molecular weight inorganic and organic anions.Graphical abstractImage 1
  • Novel enzyme-free immunomagnetic microfluidic device based on
           Co0.25Zn0.75Fe2O4 for cancer biomarker detection
    • Abstract: Publication date: Available online 24 April 2019Source: Analytica Chimica ActaAuthor(s): Camila A. Proença, Thaísa A. Baldo, Tayane A. Freitas, Elsa M. Materón, Ademar Wong, Andrés A. Durán, Matias E. Melendez, Gustavo Zambrano, Ronaldo C. Faria Early diagnosis of cancer by biomarker detection has been widely studied since it can lead to an increase in patient survival rates. Magnetic nanoparticles (MNPs) play an important role in this field acting as a valuable tool in the biomarker immunocapture and detection. In this work, Co0.25Zn0.75Fe2O4 (CoZnFeONPs) nanoparticles were synthesized and applied as enzyme mimics of peroxidase-like catalysis in a disposable enzyme-free microfluidic immunoarray device (μID). The catalytic activity of CoZnFeONPs was evaluated by hydrogen peroxide detection using cyclic voltammetry and the apparent Michaelis-Menten constant was estimated by Lineweaver–Burk equation showing good Km values. In μID, the immunosensors were assembled with monoclonal antibody against CYFRA 21-1 covalently immobilized on graphene oxide previously deposited on the screen-printed carbon-based electrodes. Under optimized conditions, the method presented a good linear response for CYFRA 21-1 in the range of 3.9-1000 fg mL-1 achieving an ultralow limit of detection (LOD) of 0.19 fg mL−1. For comparison, Fe3O4 nanoparticles (FeONPs) was also synthetized and presented results slight inferior to that obtained with CoZnFeONPs. The methods developed using both MNPs exhibited countless advantages when compared with the immunosensors developed for CYFRA-21-1, previously reported in the literature. The methods were successful applied for the detection of CYFRA 21-1 in real serum samples of healthy and prostate cancer patients and showed good correlation with results obtained with the enzyme linked immunosorbent assay (ELISA). The CoZnFeONPs associated with the disposable microfluidic immunoarray device provides a simple and effective method for biomarker detection that could satisfy the need for a low-cost and rapid test for early diagnosis of cancer.Graphical abstractImage 1
  • Derivative chiral copper(Ⅱ) complexes as template of an electrochemical
           molecular imprinting sol-gel sensor for enantiorecognition of aspartic
    • Abstract: Publication date: Available online 23 April 2019Source: Analytica Chimica ActaAuthor(s): Xiaohui Chen, Shibo Zhang, Xuelin Shan, Zhidong Chen In this work, we reported a novel electrochemical sensor for enantiorecognition of electrochemically inactive aspartic acid (Asp) enantiomers. By combining sol-gel processing with molecular imprinting technology, an enantioselective interface of molecularly imprinted sol-gel (MIS) films with imprinted cavities was prepared on the surface of a glassy carbon electrode (GCE). In order to obtain the electrochemical responses of electrochemically inactive Asp, the ternary derivative of L-aspartic, (L-aspartic acid)Cu2+(N-carbobenzoxy-L-aspartic acid), was used as the template for fabrication of MIS. The stripping currents of target molecules could be detected by square-wave stripping voltammetry due to the reduction of cupric ion on the modified electrode. The resulted sensor showed good adsorbability to L-Asp derivative, and the recognition efficiency was obtained as 2.1. Meanwhile, the L-Asp was quantitatively determined by the MIS sensor. As a result, the proposed electrochemical sensor could be regarded as a potential platform for enantiorecognition of electrochemically inactive chiral compounds.Graphical abstractImage 1
  • Solvent-Free High-Throughput Analysis of Herbicides in Environmental Water
    • Abstract: Publication date: Available online 22 April 2019Source: Analytica Chimica ActaAuthor(s): Jiaqin Wang, Qi Du, Xinrui You, Youqi Lv, Wentao Bi, Hongli Li, David Da Yong Chen A high throughput, and eco-friendly method based on solid-phase microextraction (SPME) combined with direct analysis in real time mass spectrometry (DART-MS) was established for the determination of trace pollutants in water. A laboratory-made SPME device coated with a metal organic framework (MIL-100 (M)) was fabricated for the on-site enrichment of triazine herbicides in environmental water, and the device was directly subjected to DART ionization (
  • Recent advances in aflatoxin B1 detection based on nanotechnology and
           nanomaterials-A Review
    • Abstract: Publication date: Available online 19 April 2019Source: Analytica Chimica ActaAuthor(s): Zhaohui Xue, Yixia Zhang, Wancong Yu, Juncai Zhang, Junyu Wang, Fang Wan, Yonghun Kim, Yudong Liu, Xiaohong Kou Aflatoxin B1(AFB1) is one of the most toxic mycotoxins produced by fungi and results in inevitable contamination of food and feed at very low concentrations. Therefore, there is an urgent need to implement selective, sensitive and highly convenient methods for the determination of aflatoxin B1. Among these methods, the progress of nanomaterials, owing to their high performances and versatile properties, offers great prospects for realizing highly sensitive, selective and simple detection of AFB1, overcoming the restrictions of traditional methods such as process-complicated, time-consuming, labor-intensive and instruments-expensive. Many nanomaterials have been used for the immobilization of biomolecules as signal generators or fluorescent quenchers or for signal amplification in AFB1 detection. This review highlights recent progress that has been made in the development of nanoparticle-based assays and focuses on the analytical potential of nanomaterials, such as Au/Ag nanoparticles (Au/Ag NPs), carbon-based nanoparticles (CBNs), magnetic nanoparticles (MNPs), Quantum dots (QDs) and novel nanomaterials, including up-conversion nanoparticles (UCNPs), metal-organic frameworks (MOFs) and nanomaterial-functional DNA intelligent hydrogels, as well as hybrid nanostructures. The determination of AFB1 is divided into three aspects: sample pretreatment prior to AFB1 detection, immunoassays and biosensors. The details of the detection methods and their application principles are described, and the challenges and opportunities in the field of food analysis are described.Graphical abstractImage 1
  • New approach for mapping and physiological test of silica nanoparticles
           accumulated in sweet basil (Ocimum basilicum) by LA-ICP-MS
    • Abstract: Publication date: Available online 17 April 2019Source: Analytica Chimica ActaAuthor(s): Jung Aa Ko, Naoki Furuta, H.B. Lim Behavior of silica nanoparticles (SiNPs) in sweet basil was studied using laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) as an in situ monitoring tool. Although the use of SiNP for environmental applications is interesting, detailed studies in plants for distributional mapping and quantitative determination have been difficult because the detection of 28Si+ suffers from severe molecular interference and high background in ICP-MS. In this work, yttrium/fluorescein-isothiocyanate-doped silica nanoparticles (Y/FITC-doped SiNPs) synthesized in our lab were used to substitute for undoped SiNP, allowing the doped 89Y+ to be monitored instead of 28Si+, while retaining the same surface properties. Based on this model, the physiological influence was studied by nourishing them with a nutrient solution spiked with the synthesized SiNPs and a co-pollutant, Cs ion. Mapping images obtained by LA-ICP-MS showed distinct accumulation patterns associated with exposure. For example, Cs was distributed widely over the leaves, whereas SiNPs were concentrated in specific regions such as main veins, leaf margins, and tips. Furthermore, the possible effect of SiNP and Cs on the photochemical reaction was confirmed through monitoring the change of the concentration of chlorophyll and carotenoid and the superoxide dismutase (SOD) activity.Graphical abstractImage 1
  • An ultrasensitive electrochemical detection of tryptase using 3D
           macroporous reduced graphene oxide nanocomposites by one-pot
           electrochemical synthesis
    • Abstract: Publication date: Available online 16 April 2019Source: Analytica Chimica ActaAuthor(s): Jaemyeon Lee, Young Ju Lee, Young Gyu Eun, Gi-Ja Lee In this study, we introduce an ultrasensitive and stable sensing platform based on gold nanoparticle decorated 3D reduced graphene oxide - carbon nanotube nanocomposites (GNP/CNT/rGO) for detection of tryptase (Tryp), which is a potential biomarker within nasal secretions for allergic rhinitis (AR). The GNP/CNT/rGO on the glassy carbon electrode (GCE) was fabricated through single-step one-pot electrochemical co-reduction and deposition. The GNP/CNT/rGO exhibited excellent electrocatalytic activity as the working electrode compared with bare GCE, GNP/rGO and CNT/rGO on GCEs. The enhanced performance of GNP/CNT/rGO may be attributed to 3D macroporous structures, which may provide increased surface area, faster charge transfer and lower mass transport resistance, as well as high electrocatalytic activity and good biocompatibility due to GNP. A GNP/CNT/rGO-based sandwich-type electrochemical immunosensor was fabricated for detection of Tryp, which requires high sensitivity and specificity. The GNP/CNT/rGO-based immunosensor exhibited a detection range from 100 pg/mL to 100 ng/mL, a detection limit of 50 pg/mL and a sensitivity of 1.64 μA/(ng/mL). This immunosensor possessed high selectivity, excellent reproducibility (RSD 2.1%) and high stability over approximately 1 month. Therefore, we expect that the GNP/CNT/rGO and the modified immunosensor will be useful tools for detecting Tryp in nasal secretions for clinical diagnosis of AR.Graphical abstractImage 1
  • Scanning Electrochemical Microscopy with Conducting Polymer Probes:
           Validation and Applications
    • Abstract: Publication date: Available online 15 April 2019Source: Analytica Chimica ActaAuthor(s): Marie A. Claudio-Cintrón, Joaquín Rodríguez-López Scanning electrochemical microscopy (SECM) allows spatially and temporally resolved measurements of a broad range of reactive surfaces and specimens, typically using electrochemically active metal probes. While conducting polymers (CPs) present several analytical properties of interest due to their chemical versatility, potentially enabling the measurement of ionic fluxes as well as redox processes, they have not been widely used as probe materials for SECM. CPs can be modified and fine-tuned to improve experimental parameters and they can be easily prepared by electrodeposition. In this paper, we show a new type of CP probe for SECM that retains the spatial resolution of conventional metal probes and introduces the possibility to exploit a wide range of ionic and redox systems. Poly-3,4-ethylenedioxythiophene (PEDOT) was electrochemically deposited on flat and recessed Pt microdisks to generate CP SECM probes. To demonstrate their usefulness, an insulating substrate with conducting features was imaged. Well-defined SECM feedback images were observed for both the CP well-probe and the Pt probe, proving the efficiency of the new electrode to image redox reactions. Additionally, an organosulfur compound was used as mediator taking advantage of the electrocatalytic effect PEDOT has on the molecule’s kinetics. Finally, these probes were also used in a mediator-less fashion, taking advantage of the ion flux required to electrochemically oxidize the PEDOT deposit. We investigated the impact of anion size and concentration on current-distance relationships for SECM probe positioning. CP probes pose exciting prospects for the imaging and measurement of combined redox and ionic processes in energy materials.
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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