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Publisher: Elsevier   (Total: 3183 journals)

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Showing 1 - 200 of 3183 Journals sorted alphabetically
Academic Pediatrics     Hybrid Journal   (Followers: 38, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 26, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 102, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 28, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 40, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 7)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 6)
Acta Astronautica     Hybrid Journal   (Followers: 436, 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: 3)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 11, SJR: 0.18, CiteScore: 1)
Acta Histochemica     Hybrid Journal   (Followers: 6, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 311, 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: 26, 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: 18, 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: 184, 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: 17, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 29, 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: 12, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 12, 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: 15, 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: 34, 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: 5)
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: 29, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 11, 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: 12)
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: 51, 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: 66, 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: 21, 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: 7, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 26, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 25)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 3, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 37, 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: 9, 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: 21, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 14, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 8, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 5, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 24)
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: 5)
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: 18, 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: 27, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 19)
Advances in Pharmacology     Full-text available via subscription   (Followers: 17, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 9, 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: 6)
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: 67)
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: 421, 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: 13, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 37, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 20)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 15)
Advances in Virus Research     Full-text available via subscription   (Followers: 6, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 53, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 383, 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: 12, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 475, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 18, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 31, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 44, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 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: 8, 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: 12)
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: 53, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 6, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 6, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 58, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 63, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 46, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 12)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 37, 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: 36, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 50)
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: 254, 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: 33, 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: 66, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 24, 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: 210, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 13, 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: 25, 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: 223, SJR: 1.58, CiteScore: 3)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 6, SJR: 0.937, CiteScore: 2)
Animal Reproduction Science     Hybrid Journal   (Followers: 7, SJR: 0.704, 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  [3183 journals]
  • An improvement of electrospun membrane reusability via titanium dioxide
           nanoparticles and silane compounds for the electromembrane extraction
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Afsaneh Mollahosseini, Yousef Elyasi, Mohammad Rastegari A polyacrylonitrile (PAN)/polydimethylsiloxane (PDMS) flat membrane was fabricated by electrospinning technique and modified using titanium dioxide (TiO2) nanoparticles and low-energy materials, dimethyldichlorosilane (MeSiCl2)/methyltrichlorosilane (MeSiCl3), to obtain a hydrophobic surface. The new membrane was utilized for the electromembrane extraction (EME) of model molecules including dibutyl phthalate (DBP) and bis [2-ethylhexyl] phthalate (DEHP). The parameters affecting proposed EME were optimized by the response surface methodology (RSM) based on the central composite design (CCD). The optimized values were 200 V of voltage, 20 min of extraction time, 1100 rpm of agitation rate, 10 mL of donor phase volume and 1 mL of acceptor phase volume. From the results, the performance of EME with the new (modified) membrane remained almost constant after ten extraction cycles while the extraction performance of unmodified EME steeply fell after six extraction cycles. The limits of detection (LODs) for DBP and DEHP were 7.40 and 0.08 ng mL−1, respectively. The linear dynamic range (LDR) was in the range of 100–4000 ng mL−1 for DBP and 1–2000 ng mL−1 for DEHP. The relative standard deviations (RSDs) were below 10%, and the relative recoveries were over 86%. The overall energy consumption for the extraction of the model molecules by new EME was 13.4 kWh m−3. The approach is time-efficient and cost-effective, as the fabricated membrane has better reusability than the previous membranes used for EME.Graphical abstractImage 1
  • Comprehensive analysis of chestnut tannins by reversed phase and
           hydrophilic interaction chromatography coupled to ion mobility and high
           resolution mass spectrometry
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Pieter Venter, Tim Causon, Harald Pasch, André de Villiers In this study, we report a methodology based on reversed phase LC (RP-LC) and hydrophilic interaction chromatography (HILIC) separations coupled to ion mobility (IM) and high resolution mass spectrometry (HR-MS) for the detailed analysis of hydrolysable tannins. The application of this approach to the analysis of an industrial chestnut (Castanea sativa, wood chips) tannin extract is demonstrated. A total of 38 molecular species, including a large number or isomers, were identified in this sample based on HR-MS(E) and UV absorption spectral information as well as retention behaviour in both separation modes. In total, 128 and 90 isomeric species were resolved by RP- and HILIC-LC-IM-TOF-MS, respectively. The combination of low- and high collision energy mass spectral data with complementary chromatographic separations allowed tentative and putative identification of twenty molecular species, comprising 78 isomers, in chestnut for the first time. Ion mobility resolved six new dimeric and trimeric vescalagin conformers with unique arrival (drift) times, including new conformers of roburin A-D which were not separated using either RP-LC or HILIC. HILIC was found to be the preferred separation mode for the analysis of vescalagin derivatives, while RP-LC is preferred for the analysis of ellagitannins with a cyclic glucose core. For the complete separation of the galloyl glucose species, comprehensive HILIC × RP-LC separation would be required.Graphical abstractImage 1
  • Cyclodextrin supramolecular inclusion-enhanced pyrene excimer switching
           for highly selective detection of RNase H
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Ye Xie, Ningning Wang, Yulong Li, Ting Deng, Jishan Li, Ke Zhang, Ruqin Yu Here, we report a novel fluorescence method for the highly selective and sensitive detection of RNase H by combining the use of a dual-pyrene-labeled DNA/RNA duplex with supramolecular inclusion-enhanced fluorescence. Initially, the probe is in the “off” state due to the rigidness of the double-stranded duplex, which separates the two pyrene units. In the presence of RNase H, the RNA strand of the DNA/RNA duplex will be hydrolyzed, and the DNA strand transforms into a hairpin structure, bringing close the two pyrene units which in turn enter the hydrophobic cavity of a γ-cyclodextrin. As a result, the pyrene excimer emission is greatly enhanced, thereby realizing the detection of RNase H activity. Under optimal conditions, RNase H detection can be achieved in the range from 0.08 to 4 U/mL, with a detection limit of 0.02 U/mL.Graphical abstractImage 1
  • A genetically encoded fluorescent biosensor for detecting nitroreductase
           activity in living cancer cells
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Fangyuan Xu, Mengyue Fan, Saisai Kang, Xinrui Duan Genetically encoded fluorescent biosensors are particularly promising sensors to examine biochemical processes in a complex cellular context. RNA mimics of GFP are RNA-fluorophore complexes that emit green fluorescence comparable in brightness to fluorescent proteins. The fluorophore is non-fluorescent until it binds with specific RNA. We designed and developed a dual activated fluorescent probe based on RNA mimics of GFP for the detection of an intracellular nitroreductase. Our probe only fluoresces in the presence of both the specific RNA and nitroreductase. Since we used RNA to tag cells, our probe only fluoresces when nitroreductase exists in such cells. Our detection system should benefit the study of cell biomarkers in heterogeneous cell populations. More importantly, the strategy of quenching the RNA/DFHBI complex by alkylation of the hydroxyl group in DFHBI opens new possibilities for developing various genetically encoded fluorescent biosensors based on RNA/DFHBI complexes.Graphical abstractImage 1
  • Smartphone-based chemiluminometric hybridization assays and quantitative
           competitive polymerase chain reaction
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Panagiota M. Kalligosfyri, Areti Sevastou, Iraklis K. Kyriakou, Sotirios S. Tragoulias, Despina P. Kalogianni, Theodore K. Christopoulos The present report introduces the smartphone as a simple, low-cost detector/imager for chemiluminometric hybridization assays and quantitative competitive polymerase chain reaction (QCPCR). In QCPCR the amplification products from the target and the competitor DNA have identical sizes but differ in a short sequence flanked by the primers. The products are hybridized with their cognate oligonucleotide probes, captured on microtiter wells and detected via an enzyme-catalyzed chemiluminogenic reaction using the smartphone as a detector/imager. We provide, for the first time, data on: (a) the detectability, analytical range and reproducibility of smartphone-based chemiluminometric hybridization assays of double stranded amplification products, (b) the comparison of smartphone-based detection with a conventional digital camera and a luminometer, and (c) the detectability, analytical range and reproducibility of smartphone-based QCPCR in terms of the number of copies of input target sequences in the sample prior to amplification. The limits of detection of the DNA hybridization assay based on the smartphone, digital camera and luminometer were 1.6, 2.4 and 1 pmol L−1. Smartphone-based QCPCR showed an analytical range from 137 to 9 × 105 copies of target DNA.Graphical abstractImage 1
  • Regulation of metal ion selectivity of fluorescent gold nanoclusters by
           metallophilic interactions
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Hao-Hua Deng, Xiang-Yu Fang, Kai-Yuan Huang, Shao-Bin He, Hua-Ping Peng, Xing-Hua Xia, Wei Chen Although numerous sensors have been successfully fabricated for the detection of various heavy metal ions by employing fluorescent gold nanoclusters (AuNCs) as nanoprobes, serious cross-interference often occurs when these ions coexist in samples, which results in glaring errors in quantification. In this study, glutathione-protected AuNCs (GSH-AuNCs) were synthesized and found to respond to both Cu2+ and Hg2+ via fluorescence suppression. Intriguingly, addition of Ag+ to GSH-AuNCs could completely inhibit the quenching effect of Hg2+ while not affecting the Cu2+-mediated quenching process. Ag+ can combine with Au+ on the surface of AuNCs to form a strong Ag+-Au+ metallic bond, which disrupts the interaction between Hg2+ and Au+ and thus eliminates the corresponding quenching effect. Based on this phenomenon, a simple sensing approach for highly selective and sensitive detection of Cu2+ in aqueous solution was developed using the GSH-AuNC/Ag+ complex as a fluorescent turn-off nanoprobe. The proposed method exhibited good linearity in the concentration range 0.02–10 μM with a limit of detection of 12 nM. This assay was demonstrated to be suitable for determination of Cu2+ in real water samples even in the presence of Hg2+, showing great promise as a tool for assessment of environmental security and drinking water quality.Graphical abstractAg+ can combine with Au+ on the surface of gold nanoclusters to form a strong Ag+-Au+ metallic bond, which disrupts the interaction between Hg2+ and Au+ and thus eliminates the corresponding quenching effect. Based on this phenomenon, a simple sensing approach for highly selective and sensitive detection of Cu2+ is developed.Image 1
  • Regulating the properties of carbon dots via a solvent-involved molecule
           fusion strategy for improved sensing selectivity
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Tianze Li, Shuang E, Jianhua Wang, Xuwei Chen Carbon dots (CDs) were prepared by a solvent-involved molecular fusion strategy using o-phenylenediamine (OPD) as the carbon source and formamide as the reaction solvent. The CDs possessed not only the functional groups inherited from the carbon source and the reaction solvent, but also numerous C=N groups in the structure, resulting from the Schiff base reaction between –NH2 of OPD and C=O of formamide. These functional groups endowed the final CDs with a favorable soft-base property, leading to the high tolerance level toward hard-acid type metal ions and prominent detection selectivity toward Ag+. Moreover, the obtained CDs displayed outstanding biocompatibility and low cytotoxicity, and demonstrated potential as an effective photoluminescence probe for intercellular Ag+ and Cys imaging, preventing the interference of autofluorescence from living tissues. This study focused on the solvent-involved molecular fusion strategy could provide new insights into the design of novel carbon-based nanostructures and optimization of the structure-property relationship of CDs.Graphical abstractCDs prepared via a solvent-involved molecular fusion strategy using formamide as reaction solvent exhibits prominent detection selectivity toward Ag+.Image 1
  • Metandem: An online software tool for mass spectrometry-based isobaric
           labeling metabolomics
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Ling Hao, Yuerong Zhu, Pingli Wei, Jillian Johnson, Amanda Buchberger, Dustin Frost, W. John Kao, Lingjun Li Mass spectrometry-based stable isotope labeling provides the advantages of multiplexing capability and accurate quantification but requires tailored bioinformatics tools for data analysis. Despite the rapid advancements in analytical methodology, it is often challenging to analyze stable isotope labeling-based metabolomics data, particularly for isobaric labeling using MS/MS reporter ions for quantification. We report Metandem, a novel online software tool for isobaric labeling-based metabolomics, freely available at Metandem provides a comprehensive data analysis pipeline integrating feature extraction, metabolite quantification, metabolite identification, batch processing of multiple data files, online parameter optimization for custom datasets, data normalization, and statistical analysis. Systematic evaluation of the Metandem tool was demonstrated on UPLC-MS/MS, nanoLC-MS/MS, CE-MS/MS and MALDI-MS platforms, via duplex, 4-plex, 10-plex, and 12-plex isobaric labeling experiments and the application to various biological samples.Graphical abstractImage 1
  • Binary code, a flexible tool for diagnostic metabolite sequencing of
           medicinal plants
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Qingqing Song, Jun Li, Yan Cao, Wenjing Liu, Huixia Huo, Jian-Bo Wan, Yuelin Song, Pengfei Tu The principle of chromatographic fingerprint is that certain diagnostic metabolites should be always distributed in a given plant and currently, it has been widely accepted as a promising means for medicinal plant authentication. Moreover, the chemical profile is the only evidence to clarify the ingredients of those consumable plant products, e.g. traditional Chinese medicine (TCM) prescriptions. Herein, efforts were made to describe the diagnostic metabolome of medicinal plant or TCM prescription using a binary code sequence. Forty-five well-known medicinal plants along with six relevant prescriptions were employed for concept illustration and proof. Each plant was subjected to chemical characterization, and diagnostic metabolites of all plants were gathered into a chemical pool containing 595 compounds. A robust method enabling the detection of all 595 constituents was then developed using LC coupled to scheduled multiple reaction monitoring. Analyst™ software was responsible for automatically judging the presence (defined as “1”) or absence (defined as “0”) of each analyte with a defined signal-to-noise threshold (S/N > 100). After converting each medicinal plant to a binary sequence consisting of 595 codes, an in-house database was built by involving all sequences. The potentials of sequence library retrieval towards plant authentication, preliminary chemical characterization, and deformulation of TCM prescriptions were demonstrated after that the diagnostic metabolome of each test sample was translated to a binary code sequence. Above all, binary code is a flexible tool for diagnostic metabolite sequencing of medicinal plants, and it should be an alternative tool of DNA barcoding towards plant authentication.Graphical abstractImage 1
  • Validated quantitative cannabis profiling for Canadian regulatory
           compliance - Cannabinoids, aflatoxins, and terpenes
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Alistair K. Brown, Zhe Xia, Patrique Bulloch, Ifeoluwa Idowu, Olga Francisco, Jorg Stetefeld, Jake Stout, Jeff Zimmer, Chris Marvin, Robert J. Letcher, Gregg Tomy In response to the Canadian federal government's Cannabis Tracking and Licensing System compliance standards, a quantitative method was created for cannabis analysis, and validated using Eurachem V.2 (2014) guidelines. Cannabinol, cannabidiol, cannabigerol, cannabichromene, cannabidiolic acid, cannabigerolic acid, Δ-9-tetrahydrocannabinol, and Δ-9-tetrahydrocannabinolic acid A were all analysed by scheduled multiple reaction monitoring (MRM) via LC-MS/MS and isotope dilution. In addition, aflatoxins B1, B2, G1, and G2 were also analysed by scheduled MRM via LC-MS/MS and matrix matched calibration curves in order to achieve the reporting limits (≤2 μg kg−1) set out by the European Pharmacopoeia. The LODs/LOQs were 0.50/1.7, 2.0/6.7, 0.59/2.0, and 0.53/1.8 μg kg−1, for B1, B2, G1, and G2 respectively. Thirty one terpenes were analysed by selected reaction monitoring via GC-MS/MS and isotope dilution using β-myrcene-d6 as a surrogate. All quantitative analyses can be accomplished using less than 1 g of material, with minimal solvent and consumable use, on low resolution instruments in less than 30 min of instrument time. Of important note is this method's power of selectivity, working ranges, and lack of need for extraction consumables such as SPE or QuEChERS, thereby minimising analytical costs and time.Graphical abstractImage 1
  • Two-dimensional titanate-based zwitterionic hydrophilic sorbent for the
           selective adsorption of glycoproteins
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Peng-Fei Guo, Xi-Ming Wang, Meng-Meng Wang, Ting Yang, Ming-Li Chen, Jian-Hua Wang The selective adsorption towards glycoproteins from complex biosamples is of vital importance in life science studies. A new zwitterionic hydrophilic material, i.e., a functionalized titanate nanosheet, is prepared by assembling well-dispersed gold nanoparticles (AuNPs) on the surface of ultrathin titanate nanosheets via an ion-exchange approach, followed through immobilizing l-cysteine (L-Cys) by Au-S bonding. This 2D-titanate-based zwitterionic hydrophilic material is shortly termed as L-Cys/Au/TiNSs and it exhibits transverse several hundred nanometers with an ultrathin nanosheet structure. The zwitterionic hydrophilic titanate nanosheets have strong adsorption affinity to glycoproteins, offering a large binding capacity towards immunoglobulin G (1098.9 mg g−1), which could be readily stripped into an ammonium hydroxide (NH4OH) solution (0.5%, m/v) with a recovery of 82.4%. The practical applications of L-Cys/Au/TiNSs are further proved by successful specific adsorption of IgG from human serum.Graphical abstractImage 1
  • One-step maltose-functionalization of magnetic nanoparticles based on
           self-assembled oligopeptides for selective enrichment of glycopeptides
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Li Zhang, Xuanfeng Yue, Nan Li, Hailan Shi, Jing Zhang, Zhiqi Zhang, Fuquan Dang Magnetic nanoparticles (MNPs) have been widely explored in enrichment of low-abundance glycoproteins/glycopeptides prior to mass spectrometry analysis in glycoproteomics. Currently, most functional groups for recognizing glycoproteins/glycopeptides are usually immobilized on the nanomaterial surface based on covalent modification, which suffers from multistep treatment, surface-dependence, and harsh conditions. In this work, we first report a facile and rapid method for surface functionalization and subsequent glycopeptides enrichment via one-step assembly of maltose-modified oligopeptides with a sequence of Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys (AEK8-maltose). In physiological conditions, AEK8-maltose readily self-organized into a complete coating layer dominated by β-sheets on the surface of SiO2@Fe3O4 and C@Fe3O4 MNPs, which remain intact to repeat washing with acidic organic and aqueous solutions extensively used in the sample enrichment treatments. Thus, the resulting AEK8-maltose functionalized MNPs show excellent performance in enrichment of glycopeptides in standard glycoprotein digests (24 glycopeptides from horseradish peroxidase (HRP), 31 glycopeptides from immunoglobulin (IgG)) and human serum digests (282 glycopeptides), including rapid enrichment speed (5 min), high detection sensitivity (0.001 ng/μL HRP), high selectivity (mass ratios of HRP and bovine serum albumin (BSA) digests up to 1:150), good enrichment recovery (over 86.3%), remarkable stability (repeatable for more than 8 times), and excellent renewability, which are better than or comparable with the literature results reported to date. The current work based on self-assembling oligopeptides provides a mild, economic and nontoxic procedure for one-step surface functionalization of various nanomaterials.Graphical abstractImage 1
  • Sandwich-type electrochemical immunosensor constructed using
           three-dimensional lamellar stacked CoS2@C hollow nanotubes prepared by
           template-free method to detect carcinoembryonic antigen
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Chaoyun Ma, Chulei Zhao, Wenjun Li, Yiju Song, Chenglin Hong, Xiuwen Qiao Effective treatment of cancer depends on early detection of tumor markers. In this paper, an effective template-free method was used to prepare CoS2@C three-dimensional hollow sheet nanotubes as the matrix of the immunosensor. The unique three-dimensional hybrid hollow tubular nanostructure provides greater contact area and enhanced detection limit. The CoS2@C–NH2-HRP nanomaterial was synthesized as a marker and had a high specific surface area, which can effectively improve the electrocatalytic ability of hydrogen peroxide (H2O2) reduction while increasing the amount of capture-fixed carcinoembryonic antigen antibody (anti-CEA). In addition, the co-bonded horseradish peroxidase (HRP) can further promote the redox of H2O2 and amplify the electrical signal. Carcinoembryonic antigen (CEA) was quantified by immediate current response (i-t), and the prepared immunosensor had good analytical performance under optimized conditions. The current signal and the concentration of CEA were linear in the range of 0.001–80 ng/mL, and the detection limit was 0.33 pg/mL (S/N = 3). The designed immunosensor has good selectivity, repeatability and stability, and the detection of human serum samples shows good performance. Furthermore, electrochemical immunosensor has broad application prospects in the clinical diagnosis of CEA.
  • Graphene nanoplatelet supported CeO2 nanocomposites towards
           electrocatalytic oxidation of multiple phenolic pollutants
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Chi Li, Yuanyuan Zhang, Ting Zeng, Xinyue Chen, Wenqian Wang, Qijin Wan, Nianjun Yang To explore suitable sensing materials for sensitive and selective detection of phenolic pollutants, CeO2 nanocubes, nanopolyhedras, and nanorods were synthesized by a hydrothermal method. These CeO2 nanomaterials were further loaded on the support of graphene nanoplatelets. As-synthesized nanomaterials and nanocomposites were characterized using transmission electron microscopy, X-ray diffraction and Raman spectroscopy as well as electrochemical techniques including cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. The nanocomposite of graphene nanoplatelets with CeO2 nanorods shows the highest electrochemical activity towards soluble species. Highly sensitive and selective determination of tetrabromobisphenol A, catechol, diethylstilbestrol, and nonylphenol was thus achieved at this nanocomposite based electrode. Their limits of detection were as low as 1.8, 42, 1.5 and 2.7 nM, respectively. Such an electrochemical sensor is thus promising for simple, fast and sensitive electrochemical determining of trace-leveled phenolic pollutants in water samples.Graphical abstractImage 1
  • Chiral recognition of tyrosine enantiomers on a novel bis-aminosaccharides
           composite modified glassy carbon electrode
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Jiao Zou, Jin-Gang Yu A polyaminosaccharide (chitosan, CS) and an aminosaccharide (d-galactosamine, GalN) were integrated together via hydrothermal assembly to obtain a bis-aminosaccharides composite (CS-GalN), and a novel and facile chiral sensing platform based on CS-GalN modified glassy carbon electrode (CS-GalN/GCE) was fabricated and used for electrochemical recognition of tyrosine (Tyr) enantiomers. CS-GalN composite was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and contact angle goniometry. It was observed that CS-GalN composite exhibited different binding ability for Tyr enantiomers. Under optimized experimental conditions, the oxidation peak current ratio of L-Tyr to D-Tyr (IL/ID) and the difference between their peak potentials (ΔEp = ED-EL) were 1.70 and 28 mV at CS-GalN/GCE by square wave voltammetry (SWV). In addition, the peak currents increase linearly with the concentration of Tyr enantiomers in the concentration range 0.01–1.00 mM with detection limits of 0.65 μM and 0.86 μM for L-Tyr and D-Tyr (S/N = 3), respectively. CS-GalN/GCE also exhibited the ability to determine the percentage of D-Tyr in the racemic mixture. In addition, CS-GalN/GCE possessed remarkable sensitivity, great stability as well as fine reproducibility. It could be concluded that the chiral interface of CS-GalN/GCE can provide an ideal platform for electrochemical recognition and determination of Tyr enantiomers.Graphical abstractImage 1
  • Impedimetric transducers based on interdigitated electrode arrays for
           bacterial detection – A review
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Sergi Brosel-Oliu, Natalia Abramova, Naroa Uria, Andrey Bratov Application of the impedance spectroscopy technique to detection of bacteria has advanced considerably over the last decade. This is reflected by the large amount of publications focused on basic research and applications of impedance biosensors. Employment of modern technologies to significantly reduce dimension of impedimetric devices enable on-chip integration of interdigitated electrode arrays for low-cost and easy-to-use sensors. This review is focused on publications dealing with interdigitated electrodes as a transducer unit and different bacteria detection systems using these devices. The first part of the review deals with the impedance technique principles, paying special attention to the use of interdigitated electrodes, while the main part of this work is focused on applications ranging from bacterial growth monitoring to label-free specific bacteria detection.Graphical abstractImage 1
  • Outside Front Cover
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s):
  • Ultrasensitive fluorescence detection of sequence-specific DNA via
           labeling hairpin DNA probes for fluorescein o-acrylate polymers
    • Abstract: Publication date: 11 December 2019Source: Analytica Chimica Acta, Volume 1088Author(s): Xinxiu Yang, Qianrui Liu, Dongxiao Wen, Meng Gao, Dongjian Zhang, Qiaomei Jin, Jinming Kong, Jian Zhang Sensitive detection of DNA is conducive to enhance the accuracy of diseases diagnosis and risk prediction. In this work, we report the use of activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) as a novel on-chip amplification strategy for the fluorescence detection of DNA. More specifically, the target DNA was captured by the on-chip immobilized hairpin DNA probes. Upon hybridization, exposed 3′-N3 of the hairpin was used to attach AGET ATRP initiators onto the silicon surface by click chemistry. Then, numerous fluorescent labeling linked to the end of the probes via the formation of long chain polymers of fluorescein o-acrylate, which in turn amplified the fluorescence signal for DNA detection. Under optimal conditions, it showed a good linear range from 100 fM to 1 μM in DNA detection, with the limit of detection as low as 4.3 fM. Moreover, this strategy showed good detection performance in complex real serum samples, the fluorescence intensity of 0.1 nM tDNA in 1% fetal bovine serum samples was 97.6% of that in Tris-EDTA buffer. Based on its high sensitivity, reduced cost and simplicity, the proposed signal amplification strategy displays translational potential in clinical application.Graphical abstractImage 1
  • Development of a multiplex immunochromatographic strip test and
           ultrasensitive electrochemical immunosensor for Hepatitis B virus
    • Abstract: Publication date: Available online 14 October 2019Source: Analytica Chimica ActaAuthor(s): Chutimon Akkapinyo, Porntip Khownarumit, Dujduan Waraho-Zhmayev, Rungtiva P. Poo-arporn This research proposes two methods for hepatitis B diagnosis including rapid testing and electrochemical assay. For the first method, a multiplex hepatitis B test strip was fabricated to serve as a rapid test for hepatitis B screening. It was developed to simultaneously test three essential serological markers of hepatitis B virus infection including hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (Anti-HBs) and hepatitis B core antibody (Anti-HBc). Gold nanoparticles (GNPs) were used as the signal generator on the test strip. Furthermore, a part of a paper network was incorporated on the strip for the gold-silver enhancement process. This paper network helped in decreasing the analysis time of enhancement and makes the enhancement process easier for rapid testing. The developed test strip was specific for each serological marker. The detection limits of HBsAg, Anti-HBs and Anti-HBc were obtained at 0.5, 0.3 and 0.1 μg mL-1, respectively. For the second method, electrochemical impedance spectroscopy (EIS) was applied for HBsAg detection. This method was proposed for quantitative hepatitis B detection. Anti-HBs antibodies were immobilized on a carbon screen printed electrode (SPCE) via the N-ethyl-N′-(3-(dimethylamino)propyl)carbo-diimide/N-hydroxy succinimide (EDC/NHS) couple reaction which reacted with the carboxyl group of the BSA cross-linked film on the electrode. The electrode modification process was characterized by EIS. A linear relationship between delta charge transfer resistance (ΔRct) and HBsAg concentration was obtained in the range of 5 to 3000 ng mL-1 with a detection limit of 2.1 ng mL-1. This work is appropriate for quantitative analysis because it is a simple and low-cost method to implement as the SPCE is disposable. Therefore, we hope that this research will be useful to improve hepatitis B detection in the future.Graphical abstractImage 1
  • Upconversion nanoparticles with bright red luminescence for highly
           sensitive quantifying alkaline phosphatase activity based on
           target-triggered fusing reaction
    • Abstract: Publication date: Available online 14 October 2019Source: Analytica Chimica ActaAuthor(s): Hongyu Chen, Xiao Pang, Ziqi Ni, Meiling Liu, Youyu Zhang, Shouzhuo Yao Herein, we report a novel ultrasensitive upconversion intense red fluorescence and colorimetric dual-readout strategy for the determination of alkaline phosphatase (ALP) that initially integrates enzyme-triggered cascade signals amplification (ECSAm) with rapid fusing reaction of label-free silver triangular nanoplates (AgTNPs). The sensing strategy involves four aspects. Firstly, AgTNPs with an absorption band at ∼610 nm was synthesized, which can effectively quench upconversion nanoparticles (UCNPs) fluorescence at 670 nm through the fluorescence resonance energy transfer (FRET). Secondly, when in the presence of ALP, L-ascorbic acid 2-phosphate (AAP) was transformed into ascorbic acid (AA) which can react with KIO3 to produce I2. Thirdly, the procreant I2 can quickly adsorb onto the surface of AgTNPs, then etch AgTNPs and the I2 is reduced to I-. Fourthly, the generated I- can further accelerate the fusion of AgTNPs by adsorption effect, which helps achieve ECSAm, allowing the quantitative evaluation of ALP with a satisfying detection limit of 0.035 mU/mL. In addition, the developed method has been further applied to the detection of ALP in human serum with satisfactory results. These results indicate that the dual-readout assay with a well-defined response mechanism shows good prospects in physiological and pathological studies.Graphical abstractImage 1
  • High-throughput analysis of single particles by micro laser induced
           breakdown spectroscopy
    • Abstract: Publication date: Available online 13 October 2019Source: Analytica Chimica ActaAuthor(s): Da Chen, Zhixuan Huang, Tong Wang, Yiwen Ma, Yue Zhang, Guiwen Wang, Pengfei Zhang Multi-elemental analysis of particulate matters is highly desirable for the identification of their emission sources. However, the traditional techniques for single particle analysis usually require time-consuming sample preparation procedures. We report here a system that combines bright-field microscopy with laser induced breakdown spectroscopy (LIBS), allowing rapid and multi-elemental analysis of single particles. The improved throughput of the system was benefited from the use of ultra-thin polyethylene films for particle immobilization such that their spectra were collected successively. The simple composition of the films avoided their interferences in the particles’ LIBS spectra. Moreover, the small thickness of the films allowed their rapid vaporization during laser ablation such that the plasma emissions from the particles were not quenched by their substrates. The performances of the system were demonstrated by studying the heterogeneity in particles’ compositions and discriminating dust particles with very similar chemicals, suggesting that it is a promising tool for environmental risk assessment.Graphical abstractImage 1
  • Nanotetrahedron-assisted electrochemical aptasensor with
           cooperatively-folding aptamer chimera for sensitive and selective
           detection of lysozyme in red wines
    • Abstract: Publication date: Available online 13 October 2019Source: Analytica Chimica ActaAuthor(s): Lianhui Zhao, Yunfei Huang, Xiaoyan Qi, Xiaochen Yan, Sai Wang, Xingguo Liang Although aptamers show great potential in the field of analytical chemistry, their intrinsic shortcomings of relatively weak affinity and selectivity in complex working environment limit their applicability to real analysis, because the flexibility of aptamers makes the specific aptatopes (i.e., binding sites for targets) in the conformational structure unstable and deficient. Herein, an anti-lysozyme aptamer and lysozyme were chosen as models. An aptamer chimera which could cooperatively fold to provide stable aptatopes for lysozyme was designed for improvement of the anti-lysozyme aptamers’ recognition ability, and an electrochemical aptasensor was then developed based on the aptamer chimera, with assistance of a rigid DNA nanotetrahedron as a spacer to orientate the aptamer chimera on the electrodes. The nanotetrahedron-aptamer chimera-based aptasensor presented highly sensitive and selective detection towards lysozyme in red wines, furnishing a 42-fold lower LOD (17.9 pmol L-1) and better selectivity than that of the aptasensor with the original aptamer. Moreover, the developed aptasensor was characterized by good recovery (91.3-109.0%), good accuracy, repeatability and stability, indicating the excellent practical applicability of the cooperatively-folding aptamer chimera in real world. This proof-of-concept study can be referred for any other aptamers, analytes, and samples.Graphical abstractImage 1
  • Magnetic concentration of allele-specific products from recombinase
           polymerase amplification
    • Abstract: Publication date: Available online 13 October 2019Source: Analytica Chimica ActaAuthor(s): Sara Martorell, Luis A. Tortajada-Genaro, Ángel Maquieira The studied challenge is the specific detection of low-abundant genomic variants that differ by a single nucleotide from the wild type. The combination of blocked recombinase polymerase amplification (RPA) and selective capture by probes immobilised on magnetic-core particles integrated into a flow system is presented. The sensing principle was demonstrated as the effective concentration-detection of the specific generated products was achieved. The analytical performance of resulting assay was successfully compared to PCR-based methods or array formats, providing faster effective detection of the selective products. As proof of concept, the single-nucleotide substitutions of the KRAS gene at codon 12 were studied in chip with parallel microchambers and permanent magnets. The blocked RPA products (generated at 37 °C) from tumour biopsies (extracted DNA 4 ng) provided a specific fluorescent bead-line that depends on the present mutation. The results agree with those reported by next-generation sequencing and provide new opportunities for in vitro diagnostic and personalised medicine.Graphical abstractImage 1
  • Gold-nanourchin Seeded Single-walled Carbon Nanotube on Voltammetry Sensor
           for Diagnosing Neurogenerative Parkinson’s Disease
    • Abstract: Publication date: Available online 12 October 2019Source: Analytica Chimica ActaAuthor(s): Rui Zhang, Shan Wang, Xiaoming Huang, Yihang Yang, Haitao Fan, Fan Yang, Jie Li, Xushuai Dong, Shaobin Feng, Periasamy Anbu, Subash C.B. Gopinath, Tao Xin α-synuclein is a predominantly expressing neuronal protein for understanding the neurodegenerative disorders. A diagnosing system with aggregated α-synuclein encoded by SNCA gene is necessary to make the precautionary treatment against Parkinson's disease (PD). Herein, gold-nanourchin conjugated anti-α-synuclein antibody was desired as the probe and seeded on single-walled carbon nanotube (SWCN) integrated interdigitated electrode (IDE). The surface morphology of SWCN-modified IDE and gold urchin-antibody conjugates were observed under FESEM, FETEM and AFM, the existing elements were confirmed. Voltammetry analysis revealed that the limit of fibril-formed α-synuclein detection was improved by 1000 folds (1 fM) with gold-nanourchin-antibody modified surface, compared to the surface with only antibody (1 pM). Validating the interaction of α-synuclein by Enzyme-linked Immunosorbent Assay was displayed the detection limit as 10 pM. IDE has a good reproducibility and a higher selectivity on α-synuclein as evidenced by the interactive analysis with the control proteins, PARK1 and DJ-1.Graphical abstractImage 1
  • Low Field Nuclear Magnetic Sensing Technology Based on Hydrogel-Coated
           Superparamagnetic Particles
    • Abstract: Publication date: Available online 11 October 2019Source: Analytica Chimica ActaAuthor(s): Qi-Yue Guo, Shu-Yue Ren, Jing-Yi Wang, Ye Li, Zi-Yi Yao, Hui Huang, Zhi-Xian Gao, Shi-Ping Yang Based on superparamagnetic nanoparticles, a responsive polyacrylamide hydrogel self-assembled by nucleic acid hairpin hybridization chain reaction was designed, and a universal low field nuclear magnetic resonance sensing platform was successfully constructed. As the target was gradually added, the hydrogel coating on the surface of the magnetic nanoparticle was opened layer by layer through binding with the aptamer, which specifically bonded thereto, causing different degrees of exposure of the magnetic nanoparticle, resulting in changes of low field nuclear magnetic resonance signals. This method was originally applied to the rapid detection of adenosine triphosphate (ATP), and the versatility of the method was verified using polychlorinated biphenyl 77 (PCB77). This method had the advantage of being fast, convenient, and low cost, and it can be easily operated with high repeatability. This universal method can detect a variety of targets by replacing aptamers and may be useful in controlling food quality and for rapidly detecting cancer cells in vitro.Graphical abstractImage 1
  • Controlled assembly of AIEgens based on a super-quadruplex scaffold for
           detection of plasma membrane proteins
    • Abstract: Publication date: Available online 11 October 2019Source: Analytica Chimica ActaAuthor(s): Longyi Zhu, Yang Li, Lei Zhang, Yunjie Wen, Huangxian Ju, Jianping Lei Quantification of plasma membrane proteins (PMPs) is crucial for understanding the fundamentals of cellular signaling systems and their related diseases. In this work, a super-quadruplex scaffold was designed to regulate assembly of oligonucleotide-grafted AIEgens for detection of PMPs. The nonfluorescence oligonucleotide-grafted AIEgen (Oligo-AIEgen) was firstly synthesized by attaching the AIEgen to 3′-terminus of the oligonucleotide through click chemistry. Meanwhile, the tetramolecular hairpin-conjugated super-quadruplex (THP-G4) as cleavage element and signal enhancement scaffold composited of three elements: a substrate sequence of DNAzyme in the loop region, partial hybridization region in the stem, and six guanine nucleotides to form G-quadruplex. Once the DNAzyme was anchored on the specific PMPs through aptamer-protein recognition, the substrate sequence on the loop of THP-G4 was cleaved by DNAzyme with the aid of cofactor MnII, resulting in the conformation switch of THP-G4 to the activated G-quadruplex scaffold. The latter could assemble Oligo-AIEgens to generate aggregation-induced emission (AIE) enhancement, resulting in a simple and sensitive strategy for detection of membrane proteins. Moreover, the DNAzyme continuously cut the next THP-G4 to achieve recycling amplification. Under the optimized conditions, this AIE-based strategy exhibited good linear relationship with the logarithm of MUC1 concentration from 0.01 to 10 μg mL-1 with the limit of detection down to 4.3 ng mL-1. The G4-assembled AIEgens provides a universal platform for detecting various biomolecules and a proof-of concept for AIE biosensing.Graphical abstractImage 1
  • Latent Turn-on Fluorescent Probe for the Detection of Toxic Malononitrile
           in Water and Its Practical Applications
    • Abstract: Publication date: Available online 11 October 2019Source: Analytica Chimica ActaAuthor(s): Yuna Jung, Nam Kyoo Park, Sangrim Kang, Youngbuhm Huh, Junyang Jung, Junho K. Hur, Dokyoung Kim A latent turn-on fluorescent probe for the detection of malononitrile (NCCH2CN), a precursor of hydrogen cyanide (HCN) in the mammalian tissue metabolism, is developed based on reaction-based fluorophore generation for the first time. Malononitrile is utilized within a wide spectrum of academic and industrial applications, and it is a key reagent to make o-chlorobenzylidene malononitrile (CS gas; tear gas), which is used for riot control. Due to its extensive use as well as potential health risks and the environmental pollution, malononitrile monitoring method has been required. In this paper, we discovered that our key sensing platform, 6-(dimethylamino)-3-hydroxy-2-naphthaldehyde (named Mal-P1), responds sensitively and selectively towards malononitrile. The Knovenagel condensation induced benzo[g]coumarin formation of Mal-P1 with malononitrile showed significant fluorescence turn-on response. In addition, Mal-P1 showed the malononitrile sensing ability in environmental samples (real water, CS gas) and imaging ability in biological sample (HeLa cell line) using fluorescence microscopy with low cytotoxicity. The successful demonstrations will facilitate further applications in a variety of fields.Graphical abstractturn-on fluorescent probe for the detection of toxic malononitrile is developed, which is sensitive, selective, and microscopy-applicable.Image 1
  • Determination of mercury at picogram level in natural waters with
           inductively coupled plasma mass spectrometry by using 3D printed metal
    • Abstract: Publication date: Available online 10 October 2019Source: Analytica Chimica ActaAuthor(s): Suvi Kulomäki, Elmeri Lahtinen, Siiri Perämäki, Ari Väisänen The determination of ultra-trace concentrations of Hg in natural water samples via preconcentration using 3D printed metal scavenger technique followed by inductively coupled plasma mass spectrometry (ICP-MS) was developed. The determination of Hg in certified reference material ERM-CA615 (groundwater) was performed with high accuracy and precision resulting in recovery of 100 ± 3% and RSD
  • Renewable magnetic ion-selective colorimetric microsensors based on
           surface modified polystyrene beads
    • Abstract: Publication date: Available online 10 October 2019Source: Analytica Chimica ActaAuthor(s): Sutasinee Apichai, Lu Wang, Kate Grudpan, Eric Bakker Magnetic ion-selective colorimetric microspheres based on surface modification of polystyrene beads (0.8 μm diameter) are reported for the first time. The common components of ion-selective optode sensing (chromoionophore, ion-exchanger and ionophore) and magnetic nanoparticles are adsorbed onto the surface of the polystyrene particles using a simple mixed solvent method. The average diameter of the magnetic microspheres is evaluated by dynamic light scattering as 0.79±0.06 μm. The reversible microsensors are circulated by flow and accumulated at a single spot by an applied magnet to become observable by digital camera. Hue signals are extracted from the recorded images to quantify the ratio of protonated and deprotonated form of the chromoionophore, which is the basis for optode response. The resulting magnetic microsensors respond to K+ with excellent selectivity over the range of 10-6 M to 10-2 M and a response time of t99 < 2.6±0.5 min above 10-5 M. The use of solvatochromic dyes as pH independent transducers was not successful in this application.Graphical abstractImage 1
  • High sensitivity and non-background SERS detection of endogenous hydrogen
           sulfide in living cells using core-shell nanoparticles
    • Abstract: Publication date: Available online 10 October 2019Source: Analytica Chimica ActaAuthor(s): Wen-Shu Zhang, Ya-Ning Wang, Zhang-Run Xu Endogenous hydrogen sulfide (H2S) exists in multiple physiological processes. In order to further understand the action mechanism of H2S in cells and human body, we proposed a smart surface-enhanced Raman scattering (SERS) nanoprobe, Au core-4-mercaptobenzonitrile-Ag shell nanoparticle (Au@4-MBN@Ag), for the detection of endogenous H2S in living cells based on the reaction between Ag shell and sulfide species. 4-MBN was selected as the SERS reporter to avoid interference from cellular molecules. With the sulfide concentration increasing, the Ag2S constantly formed, and consequently the SERS signal intensity of Au@4-MBN@Ag gradually decreased owing to the weaker SERS activity of Ag2S. With the nanoprobes, this method not only offers a high sensitivity for H2S detection at an nM level, but also achieves the goal of non-background analysis. It displays satisfactory anti-interference capability and a good linear relationship with sulfide concentration ranging from 50 nM to 500 μM, and an estimated detection limit is 0.14 nM. The Au@4-MBN@Ag nanoprobes were successfully applied to detect endogenous H2S in living HepG2 cells stimulated by pyridoxal 5-phosphate monohydrate. This work offers a potential analytical method in the related research of H2S physiological function.Graphical abstractImage 1
  • Competitive electrochemical aptasensor based on a cDNA-ferrocene/MXene
           probe for detection of breast cancer marker Mucin1
    • Abstract: Publication date: Available online 9 October 2019Source: Analytica Chimica ActaAuthor(s): Haiyan Wang, Jingjing Sun, Lin Lu, Xiao Yang, Jianfei Xia, Feifei Zhang, Zonghua Wang A competitive electrochemical aptasensor based on a cDNA-ferrocene/MXene probe is used to detect the breast cancer marker Mucin1 (MUC1). MXene (Ti3C2) nanosheets with excellent electrical conductivity and large specific surface area are selected as carriers for aptamer probes. The ferrocene-labeled complementary DNA (cDNA-Fc) is first bound on the surface of MXene to form a cDNA-Fc/MXene probe. Then, the MUC1 aptamer is fixed to the electrode by Au-S bonds. The sensing electrode is named Apt/Au/GCE. After the probe is complementary to the aptamer, a cDNA-Fc/MXene/Apt/Au/GCE aptasensor is fabricated. When the aptasensor is used for detection of MUC1, a competitive process happens between the cDNA-ferrocene/MXene probe and MUC1, which makes cDNA-Fc/MXene probe detach from the sensing electrode, resulting in a decrease in electrical signal. The difference in the corresponding peak current before and after the competition can be used to indicate the quantitative change in bound MUC1. The proposed competitive electrochemical aptasensor gives a wide linear range of 1.0 pM to 10 μM and a low detection limit of 0.33 pM (S/N =3), which is promising for clinical diagnosis.Graphical abstractImage 1
  • Stable Pb2+ ion-selective electrodes based on
           polyaniline-TiO2 solid contacts
    • Abstract: Publication date: Available online 9 October 2019Source: Analytica Chimica ActaAuthor(s): Xianghua Zeng, Wenen Jiang, Xiaohui Jiang, Geoffrey I.N. Waterhouse, Zhiming Zhang, Liangmin Yu A novel Pb2+ ion selective electrode based on a polyaniline-doped titanium dioxide (PANI-TiO2) solid contact, denoted herein as GC/PANI-TiO2/Pb2+-ISE, was successfully developed. The GC/PANI-TiO2/Pb2+-ISE exhibited a stable and rapid potential response to Pb2+ ions, with a linear response over the concentration range 10-3-10-9 M, a detection limit of ∼10-9.1 M and a response time of only 10-15 s. The PANI-TiO2 solid contact layer possessed a large specific capacitance, thereby effectively promoting ion-to-electron transduction and enhancing the output stability (potential drift, 122.6 μV/s). The developed electrode maintained excellent performance during continuous use, showing a linear response range of 10-3-10-7 M with no obvious changes in the potential response time or response slope (29 ± 0.2 mV/decade) over six weeks. Results encourage the wider use of conducting polymer-semiconductor solid contacts in ion selective electrode development.Graphical abstractImage 1
  • Incorporation of homochiral metal-organic cage into ionic liquid based
           monolithic column for capillary electrochromatography
    • Abstract: Publication date: Available online 9 October 2019Source: Analytica Chimica ActaAuthor(s): Zhentao Li, Zhenkun Mao, Wei Zhou, Zilin Chen Metal-organic cages (MOCs) are a novel kind of porous materials which have three dimensional structures with perpetual and well-defined holes. They have attracted wide consideration for relatively simple synthesis and potential applications such as separation, sensing, microreactor and catalysis etc. In this study, a homochiral MOC [Zn3L2] was prepared as a novel stereoselective stationary phase and adding into poly (ionic liquid-co-ethylene dimethacrylate) (Zn3L2@poly(IL-co-EDMA)) monolith for capillary electrochromatography (CEC). The chiral analytes comprising mandelic acid, benzoin and furoin enantiomers were separated perfectly using the monolithic column Zn3L2@poly(IL-co-EDMA), and the effects of buffer pH, acetonitrile percentage and buffer concentration on enantiomers separation were confirmed. Moreover, incorporation of MOC [Zn3L2] into IL polymer monolith strengthened obviously the stereoselective isolation of some positional isomers (such as nitrophenols, nitrotoluenes, xylenes, and ionones). The relative standard deviations (RSDs) of the retention time for intra-day (n = 5) and inter-day (n = 3) and column-to-column (n = 3) enantioseparations were all below 5.0%. This novel monolithic column combined distinct features of the stereoselective materials with the eminent traits of ionic liquid matrix, it has great application potential in CEC.Graphical abstractImage 1
  • Total polyphenol content and metals determination in Spanish virgin olive
           oils by means of a dispersive liquid-liquid aerosol phase extraction
           method and ICP-MS
    • Abstract: Publication date: Available online 9 October 2019Source: Analytica Chimica ActaAuthor(s): Carolina Mirón, Raquel Sánchez, Soledad Prats, José-Luis Todolí This report presents a study on the determination of total polyphenols together with metals in several samples of olive oil produced in Spain. The results provided by applying a conventional extraction method were compared against those encountered by means of the so-called Dispersive Liquid-Liquid Aerosol Phase Extraction method. The novel method is based on the dispersion of the extracting solution in the sample. To accomplish this, an aerosol is pneumatically generated and directed against the surface of the oil sample. The aerosol was generated in order to increase as much as possible the surface area of the interface between the two involved non-miscible phases. As a result, the partition equilibrium was quickly achieved. The critical variables dictating the characteristics of the obtained aerosols as well as those influencing the partition equilibrium state were studied. With the aerosol phase extraction method, the values corresponding to the total polyphenols and metals in real samples were not statistically different as compared to those obtained by the conventional liquid – liquid extraction method. The new method provided shorter extraction times and lower mass of consumed reagents than the conventional one, thus giving rise to a more environmentally friendly method. For polyphenols, calculated limits of detection and quantification were 0.48 and 1.5 mg of gallic acid kg-1, respectively. The absorbance linearity, in turn, was kept from 0 to 50 mg kg-1 (R2 = 0.998). In the case of metal and metalloid quantification, the limits of detection found with a sample digestion method ranged from 1.3 (Cu) to 291 (Na) ng mL-1. Meanwhile, because of the lower dilution factor, this parameter was one order of magnitude lower when these elements were extracted according to the new method. The new extraction method was applied to the analysis of 42 extra virgin olive oils both bottled and directly collected from the oil press, containing single cultivars or blends and produced from different areas. Fresh oils were analyzed and a preliminary study on the oil thermal degradation was also done. Dispersing the extracting solution as an aerosol into the sample can be considered a versatile method able to provide extensive oil chemical information in a rapid way what is especially important in the case of polyphenols.Graphical abstractA dispersive liquid – liquid aerosol phase extraction method has been applied optimized and validated for the determination of polyphenols and metals in extra virgin olive oils.Image 1
  • Simultaneous targeted and untargeted UHPLC-ESI-MS/MS method with
           data-independent acquisition for quantification and profiling of
           (oxidized) fatty acids released upon platelet activation by thrombin
    • Abstract: Publication date: Available online 9 October 2019Source: Analytica Chimica ActaAuthor(s): Malgorzata Cebo, Jörg Schlotterbeck, Meinrad Gawaz, Madhumita Chatterjee, Michael Lämmerhofer In this study, a combined targeted/untargeted UHPLC-ESI-QTOF-MS/MS method for the targeted quantitative analysis of the primary platelet lipid mediators thromboxane B2 (TXB2), 12S-hydroxy-5Z,8E,10E-heptadecatrienoic acid (HHT) and its oxidation product 12-keto-5Z,8E,10E-heptadecatrienoic acid (KHT) was developed, which allowed simultaneous untargeted profiling for the detection of other lipid biomarkers such as other oxylipins and fatty acids (FAs) in platelet releasates. A general procedure for the synthesis of keto-analogs from hydroxylated polyunsaturated FAs (PUFAs) using Dess-Martin periodinane oxidation reagent was proposed for the preparation of KHT standard. MS detection was performed in data independent acquisition (DIA) mode with sequential window acquisition of all theoretical fragment ion mass spectra (SWATH) in the range of 50-500 Da with variable window sizes. The LC-MS/MS assay was validated for the targeted analytes and applied for analysis of supernatants derived from resting platelets and from platelets treated with thrombin. The targeted analytes KHT, HHT and TXB2 were found at highly elevated levels in the activated platelet releasates. On average, 13 ± 7, 15 ± 9, and 0.6 ± 0.2 attomols per platelet were released upon thrombin-activation. Furthermore, the simultaneous untargeted profiling (n = 8 in each group) revealed that these oxylipins are released with a pool of other (significantly upregulated) oxidized (12-HETE, 12-HEPE) and non-oxidized PUFAs. All these compounds can be considered additional biomarkers of platelet activation complementing the primary platelet activation marker thromboxane B2. The other lipids may support platelet activation or trigger other biological actions with some potential implications in thromboinflammation.Graphical abstractImage 1
  • HPLC-ICPMS/MS shows a significant advantage over HPLC-ICPMS for the
           determination of perchlorate in ground, tap, and river water
    • Abstract: Publication date: Available online 8 October 2019Source: Analytica Chimica ActaAuthor(s): Bassam Lajin, Walter Goessler Perchlorate is an environmental contaminant that originates from anthropogenic as well as natural sources. The health effects of perchlorate with respect to the thyroid function are well known. The capabilities of the inductively coupled plasma mass spectrometry (ICPMS) has been recently expanded by coupling with tandem mass spectrometry. The advantages of HPLC-ICPMS/MS has not yet been thoroughly assessed for chlorine speciation analysis. We report a rapid and simple method for perchlorate determination in ground, tap, and river water and we show that the ICPMS/MS offers as a chromatographic detector at least 10-fold improvement in the detection limit relative to single quadrupole ICPMS. The achieved limit of detection was 0.3 μg Cl L-1 perchlorate and could be yet improved by simple freeze-drying (down to ca. 50 ng Cl L-1, based on the river water matrix), which is comparable with HPLC-ESIMS/MS, with the advantage of eliminating the need for the 18O-perchlorate isotopically labeled internal standard. The method was validated in the various water matrices in terms of recovery at levels 5.0-250 μg Cl L-1 (±10%), repeatability (
  • Near-infrared ratiometric probe with a self-immolative spacer for rapid
           and sensitive detection of alkaline phosphatase activity and imaging in
    • Abstract: Publication date: Available online 7 October 2019Source: Analytica Chimica ActaAuthor(s): Xueyan Zhang, Xiangzhu Chen, Kaizheng Liu, Yuanyuan Zhang, Gui Gao, Xiaoqian Huang, Shicong Hou Alkaline phosphatase (ALP), an enzyme that catalyzes the hydrolysis of phosphate groups, is closely associated with many diseases, including bone disease, prostate cancer, and diabetes. Thus, new assays for ALP detection in live cells are needed to better understand its role in related biological processes. In this study, we constructed a novel near-infrared ratiometric fluorescent probe for detecting ALP activity with high sensitivity. The probe uses a new self-immolative mechanism that can achieve a rapid response (within 10 min) to ALP, detected as a spectral shift (from 580 to 650 nm). This method effectively avoids issues related to instrument variability, and the near-infrared fluorescence emission (650 nm) makes it more suitable for biological detection. Moreover, the high sensitivity (14-fold enhancement of the fluorescence ratio F650/F580) and low detection limit (0.89 U L-1) for ALP allows the probe to be adapted to complex biological environments. The assay was successfully performed using serum samples with a linear range of ALP of up to 150 U L−1. We used the developed probe to detect and image endogenous ALP in cells with satisfactory results, and we successfully used the probes to detect changes in endogenous ALP levels in zebrafish caused by drug-induced organ damage.Graphical abstractImage 1
  • Ultrasensitive detection of miRNA based on efficient immobilization of
           probe and electrochemiluminescent quenching of Ru(bpy)3 2+ by methylene
    • Abstract: Publication date: Available online 5 October 2019Source: Analytica Chimica ActaAuthor(s): Liping Lu, Chang Liu, Wujian Miao, Xiayan Wang, Guanghsheng Guo A high performance miRNA biosensor based on effective click chemistry assembly of a Ru(bpy)32+ labeled DNA probe and efficient electrochemiluminescence (ECL) quenching of the Ru(bpy)32+/BDEA (BDEA = N-butyldiethanolamine) system by surface-confined electroactive methylene blue (MB) dye is reported. When the target miRNA was present, the ECL signal instantly changed from “light off” to “light on” status. Using the specific miRNA let-7d as the target analyte, this biosensor provided sensitive detection over approximately six orders of magnitude (10 fM-10 nM), with a limit of detection of 10 fM (S/N = 3). Detailed study of the ECL quenching behavior of the Ru(bpy)32+/BDEA system by MB in solution suggested that the ECL quenching involves a combination of photoluminescence dynamic quenching and quenching processes directly associated with the redox reactions, as well as resonance energy transfer. A large binding constant of 4.7×1011 M-1 between let-7d and the DNA hairpin was estimated using an ECL-based extended Langmuir isotherm model, suggesting remarkably strong binding of the target to the probe. Furthermore, our biosensor exhibited excellent specificity and reproducibility. Using the developed system, the concentration of the target miRNA extracted from the A549 cell line could be obtained, demonstrating the potential application of the developed biosensor to practical biological sample analysis.Graphical abstractImage 1
  • Enhanced Peroxidase-Like Activity of AuNPs Loaded Graphitic Carbon Nitride
           Nanosheets for Colorimetric Biosensing
    • Abstract: Publication date: Available online 4 October 2019Source: Analytica Chimica ActaAuthor(s): Na Wu, Yi-Ting Wang, Xiao-Yan Wang, Feng-Na Guo, Hui Wen, Ting Yang, Jian-Hua Wang Nanozymes have emerged as promising alternatives to overcome the high cost and low stability issues of natural enzymes. Particularly, those with peroxidase-like activities have been extensively studied to construct versatile biosensors. In this article, we demonstrate that the modification of the graphitic carbon nitride nanosheets (g-C3N4 nanosheets) by plasmonic gold nanoparticles (AuNPs) greatly enhances its catalytic performance as peroxidase mimetic. In the presence of H2O2, the AuNPs@g-C3N4 nanosheets can catalyze the redox reaction of 3,3′,5,5′- tetramethylbenzidine (TMB) to produce a blue color. Based on the observation, a colorimetric sensing method for glucose is further developed with the assistance of glucose oxidase (GOx). The linear range for glucose is from 5 to 100 μmol L-1 (R2=0.9967) and the limit of detection (LOD) is 1.2 μmol L-1. The LOD can be further lowered down to 0.75 μmol L-1 by using H2SO4 as termination agent and measuring the absorbance of the yellow product at λ=451 nm. Moreover, the practical usefulness of AuNPs@g-C3N4 nanosheets as a peroxidase nanozyme for glucose determination in human serum and urine is also demonstrated.
  • Comparison of three sample addition methods in competitive and sandwich
           colloidal gold immunochromatographic assay
    • Abstract: Publication date: Available online 4 October 2019Source: Analytica Chimica ActaAuthor(s): Yu Li, Yaofeng Zhou, Xirui Chen, Xiaolin Huang, Yonghua Xiong Immunochromatographic assays (ICAs) are mainstream point-of-care diagnostic tools in disease control, food safety, and environmental monitoring. However, the important issue pertaining to the influence of sample addition methods on the detection performance of ICAs has not been addressed, and related information is still lacking. Herein, we selected the well-accepted gold nanoparticles (AuNPs) as visual labels. AuNP-based ICA was then used to explore the effects of three sample addition methods (i.e., dry, wet, and insert) on the analytical performance of ICAs by using competitive and sandwich models. Under optimized conditions, the competitive ICA with clenbuterol as an analyte showed a negligible difference (p>0.05) in the detection performance of the three methods in ideal phosphate buffered saline solution. However, the wet method demonstrated the worst performance in pork samples (p
  • F-containing initiatior for ultrasensitive fluorescent detection of lung
           cancer DNA via atom transfer radical polymerization
    • Abstract: Publication date: Available online 4 October 2019Source: Analytica Chimica ActaAuthor(s): Jingyu Zhang, Qianrui Liu, Yanyan Ba, Jiamin Cheng, Huaixia Yang, Ying Cui, Jinming Kong, Xueji Zhang An ultrasensitive fluorescence method for early diagnosis of lung cancer via Nafion-initiated atom transfer radical polymerization (ATRP) is reported, in this paper. In the proposed method, thiolated peptide nucleic acid (PNA) is modified to amino magnetic beads (MBs) via a cross-linking agent to specifically capture target DNA (tDNA), and the initiator (Nafion) of ATRP is attached to PNA/DNA heteroduplexes based on the phosphate groups of the tDNA and sulfonate groups of Nafion via phosphate-Zr4+-sulfonate chemistry. Nafion as a macroinitiator of ATRP possesses multiple C-F active sites to initiate polymerization, and numerous polymeric chains that significantly amplify the fluorescent signal are formed. Under optimal conditions, a good linear relationship is obtained in the range of 0.1 nM∼0.1 fM with correlation coefficients of 0.9975, and the detection limit is as low as 35.5 aM (∼214 molecules). The proposed strategy has several advantages of simplicity, cost-effectiveness, selectivity and sensitivity. More importantly, the anti-interference results demonstrate that the proposed Nafion-initiated ATRP strategy has great potential in bioanalytical applications.Graphical abstractAn ultrasensitive fluorescence method for early diagnosis of lung cancer via Nafion-initiated atom transfer radical polymerization (ATRP) was reported.Image 1
  • Quantitative inkjet application on self-printed, binder-free HPTLC layers
           for submicromole-scaled analytical 1H NMR spectroscopy
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Imanuel Yüce, Milena Mayr, Gertrud E. Morlock High-performance thin-layer chromatography (HPTLC) combined with 1H nuclear magnetic resonance (NMR) spectroscopy has only been demonstrated over a small spectral range so far. The self-printing of chromatographic plates with a modified 3D slurry printer allowed the operator to influence the composition of the adsorbent slurry and thus the purity of the adsorbent layer. The combination of such self-printed, binder-free HPTLC plates with inkjet-driven sample application made possible submicromole-scaled analytical 1H NMR spectroscopy. This was proven using pure HPTLC adsorbents. For comparison, commercial silica gel HPTLC plates were purified by pre-development with solvents for spectroscopy, whereas commercial silica gel HPTLC particles were self-printed on the glass plate after purification under solvent pressure in a recycled HPLC cartridge. Evaluating the signals from different treatments, seven background signals disappeared in the proton spectra and three were reduced to a minimum by use of pre-developed commercial HPTLC plates. In the case of the self-printed, binder-free HPTLC plates made of purified adsorbent, most of the spectral background signals were reduced to a minimum, thus these spectra showed the highest cleanness and most pure analyte proton spectra. For the first time, the full 1H NMR spectroscopy range was made available after an HPTLC separation. This proof of principle opens the avenue for submicromole-scaled analytical 1H NMR spectroscopy.Graphical abstractImage 1
  • A new approach for the separation, characterization and testing of
           potential prionoid protein aggregates through hollow-fiber flow field-flow
           fractionation and multi-angle light scattering
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Valentina Marassi, Francesca Beretti, Barbara Roda, Andrea Alessandrini, Paolo Facci, Tullia Maraldi, Andrea Zattoni, Pierluigi Reschiglian, Marinella Portolani Protein misfolding and aggregation are the common mechanisms in a variety of aggregation-dependent diseases. The compromised proteins often assemble into toxic, accumulating amyloid-like structures of various lengths and their toxicity can also be transferred both in vivo and in vitro a prion-like behavior.The characterization of protein interactions, degradation and conformational dynamics in biological systems still represents an analytical challenge in the prion-like protein comprehension.In our work, we investigated the nature of a transferable cytotoxic agent, presumably a misfolded protein, through the coupling of a multi-detector, non-destructive separation platform based on hollow-fiber flow field-flow fractionation with imaging and downstream in vitro tests.After purification with ion exchange chromatography, the transferable cytotoxic agentwas analyzed with Atomic Force Microscopy and statistical analysis, showing that the concentration of protein dimers and low n-oligomer forms was higher in the cytotoxic sample than in the control preparation. To assess whether the presence of these species was the actual toxic and/or self-propagating factor, we employed HF5 fractionation, with UV and Multi-Angle Light Scattering detection, to define proteins molar mass distribution and abundance, and fractionate the sample into size-homogeneous fractions. These fractions were then tested individually in vitro to investigate the direct correlation with cytotoxicity. Only the later-eluted fraction, which contains high-molar mass aggregates, proved to be toxic onto cell cultures. Moreover, it was observed that the selective transfer of toxicity also occurs for one lower-mass fraction, suggesting that two different mechanisms, acute and later induced toxicity, are in place. These results strongly encourage the efficacy of this platform to enable the identification of protein toxicants.Graphical abstractImage 1
  • A nanocellulose-based colorimetric assay kit for smartphone sensing of
           iron and iron-chelating deferoxamine drug in biofluids
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Shadab Faham, Hamed Golmohammadi, Raouf Ghavami, Gholamreza Khayatian The current work describes the development of a “nanopaper-based analytical device (NAD)”, through the embedding of curcumin in transparent bacterial cellulose (BC) nanopaper, as a colorimetric assay kit for monitoring of iron and deferoxamine (DFO) as iron-chelating drug in biological fluids such as serum blood, urine and saliva. The iron sensing strategy using the developed assay kit is based on the decrease of the absorbance/color intensity of curcumin-embedded in BC nanopaper (CEBC) in the presence of Fe(III), due to the formation of Fe(III)-curcumin complex. On the other hand, releasing of Fe(III) from Fe(III)-CEBC upon addition of DFO as an iron-chelating drug, due to the high affinity of this drug to Fe(III) in competition with curcumin, which leads to recovery of the decreased absorption/color intensity of Fe(III)-CEBC, is utilized for selective colorimetric monitoring of this drug. The absorption/color changes of the fabricated assay kit as output signal can be monitored by smartphone camera or by using a spectrophotometer. The results of our developed sensor agreed well with the results from a clinical reference method for determination of Fe(III) concentration in human serum blood samples, which revealed the clinical applicability of our developed assay kit. Taken together, regarding the advantageous features of the developed sensor as an easy-to-use, non-toxic, disposable, cost-effective and portable assay kit, along with those of smartphone-based sensing, it is anticipated that this sensing bioplatform, which we name lab-on-nanopaper, will find utility for sensitive, selective and easy diagnosis of iron-related diseases (iron deficiency and iron overload) and therapeutic drug monitoring (TDM) of iron-chelating drugs in clinical analysis as well.Graphical abstractImage 1
  • A novel voltammetric platform based on dysprosium oxide for the sensitive
           determination of sunset yellow in the presence of tartrazine
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Aysegul Kutluay Baytak, Emine Akbaş, Mehmet Aslanoglu This study reports the preparation of a novel voltammetric platform based on the modification of a glassy carbon electrode (GCE) with carbon nanotubes (MWCNTs) and dysprosium oxide (Dy2O3) nanoparticles. The electrode material was characterized by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction method (XRD). The novel platform (Dy2O3NPs/MWCNTs/GCE) was applied for the voltammetric determination of sunset yellow (SY) in the presence of tartrazine (TAR). SY was first adsorbed at the surface of Dy2O3NPs/MWCNTs/GCE by keeping it into a solution of SY for 200 s. Afterwards, the proposed platform was washed with ultrapure water and transferred with the adsorbed species in a voltammetric cell containing only 0.1 M phosphate buffer solution (PBS). Then, the novel platform (Dy2O3NPs/MWCNTs/GCE) exhibited excellent electrocatalytic activity and presented improved voltammetric responses when compared to other electrodes. The novel platform produced an improved anodic peak at 0.705 V and a corresponding cathodic peak at 0.690 V for SY and an irreversible anodic peak at 0.957 V for TAR. When compared to the electrode modified with only MWCNTs, a remarkable increase in current response and a electrocatalytic activity of the proposed platform were observed for SY and TAR at a GCE modified with both MWCNTs and Dy2O3NPs. A linear relationship was obtained between the current response and the concentration of SY over range of 1.0 × 10−9 M −  1.4 × 10−7 M with an LOD of 3.5 × 10−10 M using square wave voltammetry (SWV). The proposed procedure provided an accurate and a precise quantification to the analysis of food and pharmaceutical samples.Graphical abstractImage 1
  • A label-free fluorescent enhancement nanosensor for ultrasensitive and
           highly selective detection of miRNA-378 through signal synergy
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Zhanmin Liu, Yanming Wang, Junhai Li, Yuanyuan Yuan, Xianyong Wu, Wenruo Liu, Youwei Liu For early detection and diagnosis of gastric cancer, a novel, highly sensitive detection of microRNA-378 was developed through rolling circle amplification and DNA-templated silver nanoclusters as a lable-free fluorescent probe. DNA-templated fluorescent silver nanoclusters (DNA/AgNCs) to make target signal cascade amplification were prepared and identified through their fluorescent spectrum. MiRNA-378 trigged rolling circle amplification to obtain the complementary sequence (cDNA) to combine with two DNA/AgNCs in the middle of a sandwich structure to induce the new fluorescent signal at a new wavelength. In the presence of microRNA-378, a large amount of RCA product cDNAs were hybridized with DNA/AgNCs as the fluorescence nanocluster beacon, resulting in fluorescence enhanced “turn-on” phenomenon. This study indicated that amplified fluorescence detection of microRNA-378 is a stable, low-cost, highly specific, and ultra-low as 1.07 fM detectability. The proposed approach of signal synergetic amplification facilitating the fluorescence detection microRNA shows great potential for potentially clinically diagnosis.Graphical abstractImage 1
  • Ligands dissociation induced gold nanoparticles aggregation for
           colorimetric Al3+ detection
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Xiaoli Luo, Xin Xie, Yingcai Meng, Taoli Sun, Jinsong Ding, Wenhu Zhou Aluminum is a very important analyte, and developing biosensors for aluminum is an important analytical task. In this work, we report a novel mechanism to design colorimetric sensor based on gold nanoparticles (AuNPs). The AuNPs were prepared by reducing HAuCl4 using catechols, and the resulting AuNPs can be directly adapted for Al3+ detection without any post-modifications, showing high sensitivity and selectivity against other metal ions. Interestingly, our mechanistic studies revealed that Al3+-induced AuNPs aggregation was not due to the formation of interparticle crosslinks that refers to the design principle of most AuNPs-based colorimetric sensors reported before. But rather, Al3+ competitively coordinated with the capping ligands on AuNPs surface through the formation of stable Al–O bond, which dissociated these ligands from AuNPs surface. As a result, the AuNPs aggregated due to the loss of surface stabilizers. Based on this mechanism, several catechols, including pyrocatechol (PC), 3-(3,4-dihydroxyphenyl) propionic acid (DHCA), levodopa (LDA) and dopamine (DA), were used as reductant to prepare AuNPs for Al3+ sensing, and the AuNPs prepared by DA (AuNPs/DA) displayed the highest sensitivity, with detection limit of 0.81 μM. The sensor was then tested for Al content analysis in river water and food samples, and the results supported its practical applications. Importantly, this work expands the design principles for colorimetric sensors by using AuNPs.Graphical abstractImage 1
  • Aptamer-functionalized magnetic metal organic framework as nanoprobe for
           biomarkers in human serum
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Zidan Wang, Xufang Hu, Nianrong Sun, Chunhui Deng Human serum is a huge bioinformatics database of human physiological and pathological state, many proteins/peptides among which can serve as biomarkers for monitoring human's health condition, thereby being worth exploring. The simple and fast capture of biomarkers from human serum is the first key step to realize their accurate detection. In this work, we developed the aptamer functionalized magnetic metal organic framework nanoprobe, and furtherly combined with mass spectrometry technology to establish an efficient method of identifying biomarkers. Taking insulin as example of biomarker in human serum, we developed sulfhydryl human insulin aptamer functionalized magnetic metal organic framework (denoted as Mag MOF@Au@HIA) through the post-synthetic modification of MIL-101(Cr)–NH2 for testing the applicability of the established method. Depending on the strong magnetic responsiveness and high specific area as well as high-loaded human insulin aptamers, the limit of detection of insulin was down to 1 ng/mL and 2 ng/mL in the standard insulin solution and human serum, respectively. Moreover, a good linear relationship (R2 = 0.998) was obtained by using standard insulin solution with concentration range from 100 ng/mL to 5 ng/mL, based on which the capture recovery of insulin with Mag MOF@Au@HIA from human serum was demonstrated to be excellent. All of the results indicate that the aptamer-functionalized magnetic metal organic framework is a promising nanoprobe for biomarkers capture in human serum.Graphical abstractMag MOF@Au@HIA was employed in detection of insulin from human serum combined with MALDI-TOF MS efficiently and sensitively.Image 1
  • Reversed-phase chromatomembrane extraction as a novel approach for
           automated sample pretreatment: Anions determination in biodiesel by ion
           chromatography with conductivity detection
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Andrey Shishov, Elena Stolarova, Leonid Moskvin, Andrey Bulatov In this study, a reversed-phase chromatomembrane extraction (RP-CME) method as a novel approach for automated sample pretreatment was suggested for the first time. The RP-CME was applied to automated separation of anions (formate, chloride, nitrate, phosphate and sulfate) from biodiesel samples as a proof-of-concept example. The novel design of chromatomembrane cell was developed for on-line RP-CME. The RP-CME procedure assumed mass-transfer of water-soluble analytes from organic sample phase (biodiesel sample) to aqueous phase supported in a porous composite mass-transfer block. The composite mass-transfer block based on microporous hydrophobic poly (tetrafluoroethylene) and hydrophilic glass fiber was developed for the RP-CME implementation. The block provided the effective retention of aqueous phase into the cell and simultaneous penetration of organic phase. The hydrophilic membrane-based sheet was used for the on-line separation of hydrophilic emulsion (biodiesel in water) containing target analytes obtained during analytes elution by aqueous phase from the mass-transfer block. The RP-CME was successfully coupled with an ion chromatography with conductivity detection. The limits of detection, calculated from a blank test based on 3σ, were 5 μg kg−1 for sulfate, 6 μg kg−1 for nitrate, 3 μg kg−1 for chloride, 5 μg kg−1 for phosphate and 1 μg kg−1 for formate.Graphical abstractImage 1
  • High throughput direct analysis of water using solvothermal headspace
           desorption with porous thin films
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Ali Azizi, Fereshteh Shahhoseini, Ali Modir-Rousta, Christina S. Bottaro Sample preparation has remained a bottleneck in analysis of biological and environmental samples. Thus, microextraction techniques to reduce time, cost, labor, and environmental impacts as compared to traditional solid phase or liquid-liquid extractions are appealing. In this work, a high throughput extraction method coupled with a novel desorption technique has been developed for the analysis of eight regulated PAHs in water. The targeted analytes were extracted by thin film microextraction (TFME) using single-use sorbents. The enriched analytes on thin films were directly introduced into a gas chromatography with a flame ionization detector (GC-FID) through solvothermal headspace desorption (ST-HD). The desorption of analytes was accelerated by adding a small volume of solvent into the headspace vial. The parameters that influence desorption, such as type and volume of solvent, oven temperature, and desorption time, were studied. As well, the key parameters (stirring rate, extraction time, and salt content) for TFME of PAHs from water were assessed and optimized. Reusability and durability of the film and background noise due to polymer decomposition were also assessed. The method was validated using standards in 3.5% aqueous NaCl. The limits of detection (LODs) were between 0.2 and 2.0 ng mL−1, with linear ranges of 0.4–200.0 ng mL−1 with R2 > 0.99, and satisfactory accuracy and repeatability at three concentrations (low, mid, and high) within the linear range of the calibration curves. The calibration curves were also assessed for suitability as a matched matrix in the analysis of PAHs in a seawater sample. The technique was also applied for determination of PAHs in a produced water sample without the need for pretreatment and filtration of the sample. Although the complexity of produced water required the use of standard addition, we demonstrated that this approach is a useful tool for the analysis of complicated environmental samples.Graphical abstractImage 1
  • Determination of tumour biomarkers homovanillic and vanillylmandelic acid
           using flow injection analysis with amperometric detection at a boron doped
           diamond electrode
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Anna Němečková-Makrlíková, Tomáš Navrátil, Jiří Barek, Pavla Štenclová, Alexander Kromka, Vlastimil Vyskočil A new method for the simultaneous determination of two tumour biomarkers, homovanillic (HVA) and vanillylmandelic acid (VMA), using flow injection analysis (FIA) with amperometric detection (AD) at a commercially available boron doped diamond electrode (BDDE) was developed. It was found that this method is suitable for the determination of HVA (in the presence of VMA) and VMA (in the presence of HVA) in optimum medium of Britton-Robinson buffer (0.04 mol L−1, pH 3.0). Calibration dependences consist of two linear parts for both biomarkers, the first one being in the concentration range from 1 to 10 μmol L−1 and the second one from 10 to 100 μmol L−1 (with obtained LODs 0.44 μmol L−1 for HVA and 0.34 μmol L−1 for VMA, respectively). To minimize any negative effects related to the passivation of the working electrode, suitable cleaning pulses (+2.4 V for 30 s) were imposed on the working electrode after each measurement. An attempt to use FIA with multiple pulse amperometric detection to determine both analytes in one run was not successful. Changing potentials in short intervals in multiple pulse detection probably results in mutual interaction of analytes and/or products of their electrochemical oxidation, thus preventing the application of this approach.Graphical abstractImage 1
  • Enhanced sensitivity of scanning bipolar electrochemical microscopy for
           O2 detection
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Carla Santana Santos, Felipe Conzuelo, Vera Eßmann, Mauro Bertotti, Wolfgang Schuhmann The Scanning Bipolar Electrochemical Microscope (SBECM) allows precise positioning of an electrochemical micro-probe serving as bipolar electrode that can be wirelessly interrogated by coupling the electrochemical detection reaction with an electrochemiluminescent reporting process. As a result, the spatially heterogeneous concentrations of an analyte of interest can be converted in real time into a map of sample reactivity. However, this can only be achieved upon optimization of the analytical performance ensuring adequate sensitivity. Here, we present the evaluation and optimized operation of the SBECM for the detection of small changes in local O2 concentrations. Parameters for achieving an improved sensitivity as well as possibilities for improving the signal-to-noise ratio in the optical signal readout are evaluated. The capability of the SBECM for O2 detection is shown at controlled conditions by recording the topography of a patterned sample and monitoring O2 evolution from a photoelectrocatalyst material.Graphical abstractImage 1
  • A label-free IFN-γ aptasensor based on target-triggered allosteric
           switching of aptamer beacon and streptavidin-inorganic hybrid composites
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Lingling Xu, Sheng Lei, Zi Liu, Gangfeng Ouyang, Lina Zou, Baoxian Ye A label-free electrochemical aptasensor was developed for the sensitive detection of interferon-gamma (IFN-γ). To do this, a diblock dual-aptamer allosteric hairpin (DDAH) was designed, followed by conjugation with gold nanoparticles (DDAH&AuNP). The presence of target destroyed the stable hairpin structure, and then the catalytic cleavage of DNAzymes removed the IFN-γ-binding molecules, triggering the allosteric switching from inactive hairpin to active streptavidin aptamer (A-DDAH&AuNP) in homogeneous system. Moreover, streptavidin-inorganic hybrid nanoflowers decorated with graphene composites (SFG) were synthesized and used as substrates to modify glassy carbon electrodes (SFG/GCE). SFG specifically bind to the A-DDAH&AuNP to realize high-efficient readout of signals. Under the optimal conditions and by using differential pulse stripping voltammetry (DPSV), the response peak currents increases linearly with the logarithm of the IFN-γ concentration in the range between 0.1 pg mL−1 and 500 ng/mL. The detection limit is as low as 19 fg mL−1. The aptasensor also has excellent electrochemical performances, which exhibits broad application prospects in biometric analysis.Graphical abstractImage 1
  • A new scattering correction method of different spectroscopic analysis for
           assessing complex mixtures
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Long Li, Yankun Peng, Yongyu Li, Fan Wang Physical properties such as particle size distribution and compactness have significant confounding effects on the spectral signals of complex mixtures, which multivariate linear calibration methods such as partial least-squares (PLS) cannot effectively model or correct. Therefore, these effects significantly deteriorate calibration models’ predictive abilities for spectral quantitative analysis of complex mixtures. Here, new scattering correction methods were proposed to estimate the additive and multiplicative parameters considering light scattering effects in each spectrum and hence mitigate the detrimental influence of additive and multiplicative effects on quantitative spectroscopic analysis of complex mixtures. Three different correction methods were proposed to estimate the addition coefficient based on two different underlying assumptions, namely, whether this coefficient is related to the wavelength. After addition coefficient elimination, the multiplicative parameter can be eliminated by a simple but very efficient spectral ratio method. Furthermore, linear models are built with key variables, and the predictive performance of these models is verified using the root-mean-square error of prediction datasets. The proposed methods were tested on one apple data set and two publicly available benchmark datasets (i.e., near-infrared spectral data of meat and powder mixture samples) and compared with some existing correction methods. The results showed that (1) additive effects of different types of samples can be eliminated by different methods and (2) these methods can appreciable improve quantitative spectroscopic analysis of complex mixture samples. This study indicates that accurate quantitative spectroscopic analysis of complex mixtures can be achieved through the combination of additive effect elimination and the spectral ratio method.Graphical abstractImage 1
  • Feature visualization of Raman spectrum analysis with deep convolutional
           neural network
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Masashi Fukuhara, Kazuhiko Fujiwara, Yoshihiro Maruyama, Hiroyasu Itoh We demonstrate a recognition and feature visualization method that uses a deep convolutional neural network for Raman spectrum analysis. The visualization is achieved by calculating important regions in the spectra from weights in pooling and fully-connected layers. The method is first examined for simple Lorentzian spectra, then applied to the spectra of pharmaceutical compounds and numerically mixed amino acids. We investigate the effects of the size and number of convolution filters on the extracted regions for Raman-peak signals using the Lorentzian spectra. It is confirmed that the Raman peak contributes to the recognition by visualizing the extracted features. A near-zero weight value is obtained at the background level region, which appears to be used for baseline correction. Common component extraction is confirmed by an evaluation of numerically mixed amino acid spectra. High weight values at the common peaks and negative values at the distinctive peaks appear, even though the model is given one-hot vectors as the training labels (without a mix ratio). This proposed method is potentially suitable for applications such as the validation of trained models, ensuring the reliability of common component extraction from compound samples for spectral analysis.Graphical abstractImage 1
  • Cork sheet as a sorptive phase to extract hormones from water by
           rotating-disk sorptive extraction (RDSE)
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Valentina Manzo, Jairón Goya-Pacheco, Daniel Arismendi, Mercedes Becerra-Herrera, Alver Castillo-Aguirre, Rosario Castillo-Felices, Milton Rosero-Moreano, Eduardo Carasek, Pablo Richter This work reports for the first time the use of laminar cork as a sorptive phase in a microextraction technique, rotating-disk sorptive extraction (RDSE). Typical hormones (estrone, estradiol, estriol and ethinyl estradiol) were selected as analyte models and extracted from wastewater samples on laminar cork with statistically equivalent extraction efficiency to that provided by Oasis HLB. The cork characterization was performed by confocal fluorescence microscopy (CLSM), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), allowing the identification of lignin, suberin and polysaccharides (cellulose and hemicellulose) as the main components of the cork. The best conditions for extraction were as follows: rotation velocity of the disk, 2000 rpm; extraction time, 45 min; and sample volume, 20 mL. The analytical features of the developed method show that calibration curves for all analytes have R2 values higher than 0.99. The absolute recoveries were higher than 63%, and the precision, expressed as relative standard deviation, ranged from 2 to 16%. The LOD and LOQ ranges were 3–19 and 10–62 ng L−1, respectively. The proposed method was applied to the analysis of wastewater, and the concentrations of hormones in a wastewater treatment plant in Santiago, Chile, ranged from
  • Outside Front Cover
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s):
  • Detachable nanoladders: A new method for signal identification and their
           application in the detection of ochratoxin A (OTA)
    • Abstract: Publication date: 9 December 2019Source: Analytica Chimica Acta, Volume 1087Author(s): Xiangli Shao, Longjiao Zhu, Yuxiang Feng, Yangzi Zhang, Yunbo Luo, Kunlun Huang, Wentao Xu A highly sensitive fluorescence turn-off biosensor for the detection of ochratoxin A (OTA) was developed based on graphene oxide (GO) and an aptamer-induced detachable nanoladders. In this assay, two types of ssDNA (H1 and H2) were involved in the assembly of the DNA nanoladders, in which H1 was labeled with fluorophore, and H2 was the OTA binding aptamer. Self-assembly of the DNA nanoladders with the addition of GO weakened its adsorption and the fluorescence intensity remained strong. In the presence of OTA, the aptamer was specifically recognized and an aptamer-OTA complex was formed, leading to the detached of DNA nanoladders. With the addition of GO, the released H1 was adsorbed on the GO surface, thus efficiently quenching the fluorescence signal (turning off). The detection limit of OTA in this assay was 4.59 nM. To improve the sensitivity of this strategy, we creatively developed an alternative strategy to replace the sturdy nanoladders with frail nanoladders. More precisely, the sequences of H1 had mismatched bases, which, when hybridized with H2 could be used to create long non-perfect complementary nanoladders. For the mismatched bases-based frail nanoladders, it was easier for OTA to bind its aptamer sequence, thus enabling a more thorough and faster detachment of the nanoladders, along with a greater degree of fluorescence quenching. The detection limit for OTA was estimated to be 0.1 nM. The biosensors we developed were sensitive, specific, enzyme-free, cost-effective and can be applied in red wine samples spiked with known concentration of OTA.Graphical abstractImage 1
  • A new dicyanoisophorone-based ratiometric and colorimetric near-infrared
           fluorescent probe for specifically detecting hypochlorite and its
           bioimaging on a model of acute inflammation
    • Abstract: Publication date: Available online 3 October 2019Source: Analytica Chimica ActaAuthor(s): Jinshuai Lan, Jing Guo, Xiaoyi Jiang, Yi Chen, Zhenghao Hu, Yuanfang Que, Hongxin Li, Jingyi Gu, Rodney J.Y. Ho, Ruifeng Zeng, Yue Ding, Tong Zhang To explore how hypochlorous acid (HClO) affects human health, a highly sensitive, selective, and trace detection method for hypochlorite (ClO−) is crucial for determining its non-negligible function in both environment and living systems. Herein, a dicyanoisophorone-phenylboronic acid-based novel ratiometric near-infrared fluorescent probe (Probe 1) was designed for the rapid and specific detection of ClO− based on the intramolecular charge transfer (ICT) mechanism. Excess addition of HClO to the Probe 1 solution, 186-times ratio (I652/I582) augment were gained. And this probe provided a colorimetric and ratiometric fluorescence response to ClO− with a high selectivity, a rapid response (within 30 s), and had an extremely low detection limit (15.7 nM). In addition, owing to the good sensing properties and low cytotoxicity of Probe 1, it can be used to expediently visualize exogenous ClO− in HepG2 cells and endogenous ClO− in RAW264.7 macrophage cells. Furthermore, the probe was successfully used for the bioimaging of zebrafish with an acute inflammation. Thus, Probe 1 is a promising vehicle to identify the level of HClO in animals with associated diseases.Graphical abstractA new ratiometric and colorimetric NIR fluorescent probe (Probe 1) for the specific detection of ClO− has been designed and synthesized on the basis of dicyanoisophorone-phenylboronic acid. And it was endowed with the following outstanding advantages: one-step synthesis, a long-wavelength emission, naked-eye assay, ratio fluorescent dual-channel detection, and feasibility in living cells and zebrafish.Image 1
  • Amino bearing core-shell structured magnetic covalent organic framework
           nanospheres: preparation, postsynthetic modification with phenylboronic
           acid and enrichment of monoamine neurotransmitters in human urine
    • Abstract: Publication date: Available online 3 October 2019Source: Analytica Chimica ActaAuthor(s): Yanping Wang, Shaoping Wu, Dan Wu, Jiwei Shen, Yinmao Wei, Chaozhan Wang Covalent organic frameworks (COFs) have been increasingly employed in separation science, including sample preparation. Herein we fabricated the amino bearing core-shell structured COFs nanospheres [Fe3O4@TpBD(NH2)2], and a novel magnetic boronate affinity adsorbent was synthesized by postsynthetic modification of the Fe3O4@TpBD(NH2)2 with 2-formylphenylboronic acid. The magnetic boronate affinity adsorbent possesses fast magnetic response and high binding capacity up to 1037 μmol g−1 for dopamine. Besides, it was used as an adsorbent for extraction of urinary monoamine neurotransmitters at neutral pH. A method for detection of the monoamine neurotransmitters was developed by coupling the magnetic solid phase extraction with high-performance liquid chromatography-fluorescence detection. Under the optimized conditions, a good analytical method was obtained in the linear dynamic range of 2 - 200 ng mL-1 with R2 between 0.9917 and 0.9966, with low limit of detection (0.31 - 0.54 ng mL-1) and limit of quantification (1.04 - 1.80 ng mL-1). The recoveries of the monoamine neurotransmitters were in the range of 86.3 - 115 %, with relative standard deviations of 2.34 - 10.5 % (intra-day) and 2.84 -14.4 % (inter-day). The method was successfully applied to the determination of the monoamine neurotransmitters in human urine samples. This work is of great importance for preparing functionalized core-shell structured magnetic covalent organic framework nanospheres, it also demonstrates the feasibility of the functionalized magnetic COFs as adsorbents in sample pretreatment.Graphical abstractImage 1
  • Exploring the sulfur species in wine by HPLC-ICPMS/MS
    • Abstract: Publication date: Available online 3 October 2019Source: Analytica Chimica ActaAuthor(s): Bassam Lajin, Walter Goessler The recent development of the inductively coupled plasma tandem mass spectrometry (ICPMS/MS) offers exciting opportunities for non-metal speciation analysis. In this work, we report the first sulfur speciation study in wine by HPLC-ICPMS/MS. The major sulfur compounds were found to be sulfate (50-81 mg S L-1) followed by sulfite (18-24 mg S L-1 free sulfite & 41-63 mg S L-1 after base hydrolysis). We detected small amounts of methionine in wine (0.5-1.0 mg S L-1); Thiosulfate was below the detection limit of 0.1 mg S L-1 (injection volume 1.0 μL). Additionally, we observed a few unknown compounds (collectively 1.0-2.0 mg S L-1) in the chromatograms. Overall, the sum of detected species accounted for only 65-77 % of total sulfur concentration (105-165 mg S L-1). To investigate this gap, we performed several chemical treatments of wine including hydrolysis, oxidation, and enzymatic digestion and then re-examined the distribution of sulfur species. Furthermore, we developed a chromatographic method involving the direct determination of sulfite. The recovery was within the range of 98-106% and repeatability (RSD%) in the range of 6.9-9.4 % in regular and “sulfite-free” red and white wine. The pH of the mobile phase drastically influenced the chromatographic behavior of the sulfite ion. At neutral pH a significant tailing and a more than 10-fold loss in peak area was observed. This effect was not previously reported and must be taken into consideration when attempting direct chromatography of sulfite.Graphical abstractImage 1
  • A Sensitive and Selective Electrochemical Sensor Based on N, P-Doped
           Molybdenum Carbide@Carbon/Prussian Blue/Graphite Felt Composite Electrode
           for the Detection of Dopamine
    • Abstract: Publication date: Available online 2 October 2019Source: Analytica Chimica ActaAuthor(s): Sen Yang, Jihua Zhao, Simon Tricard, Laxian Yu, Jian Fang In this paper, a composite electrode of N,P-doped Mo2C@C/Prussian blue (PB)/graphite felt (N,P-Mo2C@C/PB/GF) was prepared by a simple method and used for sensitive and effective detection of dopamine (DA). N,P-doped Mo2C nanospheres were prepared by using phosphomolybdic acid (PMo12) as an initiator to promote the polymerization of polypyrrole. Such nanospheres were used to accelerate the deposition process of PB from K3[Fe(CN)6] and FeCl3 in solution. The N,P-Mo2C@C/PB nanohybrid was then anchored to GF in order to obtain the electrochemical sensor. Two linear ranges were extrapolated for dopamine detection: from 0.18 to 30 μmol·L-1 with a sensitivity of 0.268 μA·μmol-1, and from 30 to 280 μmol·L-1 with a sensitivity of 0.045 μA·μmol-1. The device showed a detection limit as low as 0.011 μmol·L-1, an excellent selectivity to DA over common interfering analytes, and a favorable long-time stability. Finally, the sensor was used for quantitative analysis of DA in the 10-fold dilution of human serum (10%) and exhibited a satisfactory recovery.Graphical abstractImage 1
  • A novel smartphone-based CD-spectrometer for high sensitive and
           cost-effective colorimetric detection of ascorbic acid
    • Abstract: Publication date: Available online 2 October 2019Source: Analytica Chimica ActaAuthor(s): Liubing Kong, Ying Gan, Tao Liang, Longjie Zhong, Yuxiang Pan, Dmitry Kirsanov, Andrey Legin, Hao Wan, Ping Wang As a powerful tool for medical diagnosis and bioanalysis, conventional optical spectrometers are generally expensive, bulky and always require an accompanying data processing device. In this work, we developed a novel smartphone-based CD-spectrometer (SCDS) for high sensitive and ultra-portable colorimetric analysis, with the advantage of cost-effective and simplicity. The distance between the light source and slit, the structure of SCDS and the parameters of camera in the smartphone were all optimized to ensure the best analytical performance. Besides, the SCDS employed HSV color model and utilized the overall intensity calculated by summing V-value of adjacent position for the absorbance measurement. In this way the errors caused by the low resolution of CD-grating can effectively be eliminated to promote the sensitivity of the SCDS. The performance of the SCDS was first validated for colorimetric detection of BSA with a detection limit of 0.0073 mg/ml, which is superior compared to that of the microtiter plate reader (MTPR). Moreover, by combining with 3,3',5,5'-tetramethylbenzidine-manganese dioxide (TMB-MnO2) nanosheets reaction, a high sensitive and specific system for ascorbic acid detection was established. The SCDS gives a detection range from 0.6250 μM to 40 μM with a detection limit of 0.4946 μM for AA detection. Compared to other studies, the SCDS features wide detection range and very low detection limit with low cost instrument. Therefore, the SCDS will be an ideal and promising colorimetric system for point-of-care (POC) application in food security, disease diagnosis and environmental monitoring.Graphical abstractImage 1
  • Energy-efficient Construction of Thermally Stable Superhydrophobic
           Nanoscale Stacked Lamellae Based Solid-phase Microextraction Coating for
           the Determination of non-polar Compounds
    • Abstract: Publication date: Available online 27 September 2019Source: Analytica Chimica ActaAuthor(s): Songbo Wei, Yan Liu, Xiaoxue Kou, Siming Huang, Guosheng Chen, Linyan Xu, Qing Tong, Fang Zhu, Jianqiao Xu, Gangfeng Ouyang Herein, through a facile and energy-friendly approach, thermally stable manganese-derived amorphous stacked nanosheet (MASNS) coatings with controlled wetting property ranging from superhydrophilicity to superhydrophobicity were synthesized. The superhydrophobic MASNS coating exhibited remarkable selectivity and sensitivity in the solid phase microextraction (SPME) of non-polar aromatic analytes, even amid the abundance of polar compounds, due to the superhydrophobic effect and the stacked lamellar structures. The established method was applied to the determination of polycyclic aromatic hydrocarbons (PAHs), featuring low LODs (i.e., 0.14 to 0.24 ng·L-1) and wide linear ranges (e.g., 10 to 10000 ng·L-1). Extraction and desorption conditions were optimized to unleash the potential of the fiber before it was applied to the analysis of target analytes in real water samples, where satisfactory recoveries were obtained (81.7% to 114.2%). This work might provide critical insights for the scalable production of superhydrophobic nanosheets as affordable and high-performance adsorbents.Graphical abstractImage 1
  • Mixed-mode Chromatography Characteristics of Chiralpak ZWIX(+) and
           ZWIX(–) and Elucidation of their Chromatographic Orthogonality for
           LC×LC Application
    • Abstract: Publication date: Available online 27 September 2019Source: Analytica Chimica ActaAuthor(s): Stefanie Bäurer, Martina Ferri, Andrea Carotti, Stefan Neubauer, Roccaldo Sardella, Michael Lämmerhofer Two-dimensional liquid chromatography requires orthogonal columns and/or separation principles in the first and second separation dimension. It is sometimes not straightforward to achieve. Chiral columns could expand the toolbox for 2D-LC, but are rarely exploited for this purpose, not least due to missing understanding of retention principles under non-chiral application conditions. To gain more insight, in this study Chiralpak ZWIX(+) and ZWIX(-), based on zwitterionic quinine and quinidine carbamate selectors, were carefully characterized by molecular dynamics simulations, lipophilicity/hydrophilicity measurements of selectors, pH-dependent ζ-potential determinations, and chromatographic characterization in RPLC and HILIC modes combined with unsupervised principal component analysis to extract classification of these columns in comparison to a number of commercial benchmarks (RP, HILIC and mixed-mode columns). The results showed that these chiral columns can be classified as mixed-mode chromatography phases with balanced lipophilic-hydrophilic surface character, excess of negative net charge due to sulfonic acid groups (in spite of weakly basic quinuclidine and quinoline rings), and multimodal applicability (RP, HILIC and polar organic elution modes). Orthogonality mapping in comparison to a number of modern HILIC and mixed-mode columns revealed that Poroshell HILIC-Z (with a zwitterionic ligand on 2.7 μm core-shell particles) can be beneficially combined as second dimension with the ZWIX column for comprehensive LC×LC. The online hyphenation of this 2D-LC system with complementary detection modalities including UV (DAD for chromophoric substances), charged aerosol detection (for universal detection and calibration of non-volatile analytes) and high-resolution mass spectrometry (ESI-QTOF-MS/MS for identification) provided an advanced method for comprehensive impurity profiling, applicable for instance for amino acid pharmaceutical products.Graphical abstractImage 1
  • A strategy for identifying species-specific peptide biomarkers in
           deer-hide gelatin using untargeted and targeted mass spectrometry
    • Abstract: Publication date: Available online 26 September 2019Source: Analytica Chimica ActaAuthor(s): Rui Liu, Yong Huang, Haokun Xu, Yunfeng Zheng, Yang Liu, Shuying Han, Min Yang, Yu Xie, Kaixuan Wang, Jin-ao Duan, Lingjun Li Deer-hide gelatin (DHG) is an important animal-derived traditional Chinese medicine (TCM), which has been applied in TCM for over 400 years. However, it is extremely difficult to distinguish DHG with adulteration or made with other animal skins due to the highly processing procedure. Therefore, a simple strategy for identifying species-specific peptide biomarkers in deer-hide gelatin (DHG) is needed. In the present study, untargeted and targeted mass spectrometry approaches were implemented to analyze comprehensive peptidomic profiles of trypsin-digested animal gelatins. Mathematics set theory was then used to interrogate the relationship between different samples and peptides in the target species set, while the peptides were not considered as species-specific biomarkers in other sets. Two peptides were identified as DHG-specific peptides. Targeted mass spectrometry approach was then used to verify these two peptides. It showed that these two peptides could be used for distinguishing DHG from other animal hide gelatins. The present strategy provides a simple method for peptide biomarker discovery, which can be applied in the identification of specific peptides in some highly processed animal derived traditional Chinese medicines (TCMs). Thus, the present work provides an effective strategy for rapid, simple discovery and application of species-specific peptide biomarkers to ensure animal derived TCMs quality and make them authenticable and traceable.Graphical abstractImage 1
  • Ambient Light Sensor Based Colorimetric Dipstick Reader for Rapid
           Monitoring Organophosphate Pesticides on a Smart phone
    • Abstract: Publication date: Available online 26 September 2019Source: Analytica Chimica ActaAuthor(s): Qiangqiang Fu, Chunlei Zhang, Jun Xie, Zhaohui Li, Lingbo Qu, Xiaoli Cai, Hui Ouyang, Yang Song, Dan Du, Yuehe Lin, Yong Tang Organophosphate pesticides (OPs) are widely used around the world to control pests in agricultural, residential, and commercial settings. Ingestion of high-dose OPs could lead to acute toxicity, and persistent influence on health could result from acute poisoning or long-term exposure to low dose OPs. An easy to operate, low cost and home available OPs testing platform is urgently needed. Ambient light sensor (ALS) based smart phone colorimetric reader has the advantages of easy to operate, low cost, high accuracy and versatility. In this work, a novel ALS based smart phone colorimetric dipsticks (CDs) reader was reported for rapid monitoring OPs. In this method, acetylcholinesterase (ACHE) CDs was used to test OPs and results were analyzed using an ALS based reader according to the absorbance of ACHE CDs. The results obtained using the ALS based CDs reader were comparable to those obtained using gas chromatography-mass spectrometry (GC-MS) and Ellman assay. The ALS based CDs reader has the advantages of portable, low cost, and high accuracy, and therefore could act an effective platform for OPs monitoring.Graphical abstractImage 1
  • Label-free peptide nucleic acid biosensor for visual detection of multiple
           strains of Influenza A Virus suitable for field applications
    • Abstract: Publication date: Available online 25 September 2019Source: Analytica Chimica ActaAuthor(s): Naveen Kumar, Sandeep Bhatia, Atul Kumar Pateriya, Richa Sood, S. Nagarajan, Harshad V. Murugkar, Satish Kumar, Praveen Singh, Vijendra Pal Singh Accurate and rapid diagnosis of Influenza A viruses (IAVs) is challenging because of multiple strains circulating in humans and animal populations, and the emergence of new strains. In this study, we demonstrate a simple and rapid strategy for visual detection of multiple strains of IAVs (H1 to H16 subtypes) using peptide nucleic acid (PNA) as a biosensor and unmodified gold nanoparticles (AuNPs) as a reporter. The design principle of the assay is based on the color change on account of free PNA-induced aggregation of AuNPs in the presence of non-complementary viral RNA sequence and vice-versa. The assay could detect IAV RNA with a visual limit of detection of 2.3 ng. The quantification of RNA with a considerable accuracy on a simple spectrophotometer was achieved on plotting the PNA-induced colorimetric changes (absorption ratio of A640/A520) in the presence of a varying concentration of complementary RNA. As a proof-of-concept, the visual assay was validated on 419 avian clinical samples and receiver operating characteristic (ROC) curve analysis showed a high diagnostic specificity (96.46%, 95% CI = 93.8 to 98.2) and sensitivity (82.41%, 95% CI = 73.9 to 89.1) when RT-qPCR was used as reference test. Hence, the simplicity, rapidity, and universality of this strategy make it a potential candidate visual assay for clinical diagnosis and surveillance of IAVs, especially in the resource-limited settings. The proposed strategy establishes new avenues for developing a simple and rapid diagnostic system for viral infections and biomolecules.Graphical abstractImage 1
  • Comprehensive identification of steroid hormones in human urine based on
           liquid chromatography-high resolution mass spectrometry
    • Abstract: Publication date: Available online 25 September 2019Source: Analytica Chimica ActaAuthor(s): Yuanyuan Zheng, Hongzhi Zhao, Lin Zhu, Zongwei Cai Steroid hormones, structural derivatives of cyclopentanoperhydrophenanthrene, play important roles in modulation of many physiological processes. Comprehensive characterization of steroid hormones is valuable for understanding the process of human life activities and even disease diagnosis. Hitherto systematical characterization of steroid hormones has been rarely investigated. Here, we presented an integrated method for human urine analysis based on ultra-high performance liquid chromatography-high resolution mass spectrometry in data-dependent acquisition mode with the following parallel reaction monitoring mode. To process the data acquired by two scan modes, a comparative study of standards’ fragmentation behaviors and diagnostic product ions (DPIs) were firstly conducted to facilitate the characterization of steroid hormones. The fragmentation behaviors, DPIs, elemental composition and double-bond equivalent were then simultaneously utilized for systematical characterization of steroid hormones in human urine. Consequently, fragmentation pathways and DPIs for all types of steroid hormones were comprehensively interpreted. It is interesting to find that dehydration is not restricted in the form of hydroxyl groups loss, elimination of the carbonyl oxygen could also generate dehydrated ions. Ultimately, a total of 80 and 107 steroidal hormones were characterized or tentatively identified in human urine of male and female, respectively. The proposed method is expected to provide valuable insights for chemical characterization in complex matrixes.Graphical abstractImage 1
  • Liposome Artificial Membrane Permeability Assay by
           MALDI-hydrogen-deuterium exchange mass spectrometry for peptides and small
    • Abstract: Publication date: Available online 25 September 2019Source: Analytica Chimica ActaAuthor(s): Alexey A. Makarov, Gregory F. Pirrone, Vladimir Shchurik, Erik L. Regalado, Ian Mangion The pharmaceutical industry’s focus has expanded to include peptide and protein-based therapeutics; however, some analytical challenges have arisen along the way, including the urgent need for fast and robust measurement of the membrane permeability of peptides and small proteins. In this study, a simple and efficient approach that utilizes MALDI-TOF-MS to study peptide and protein permeability through an artificial liposome membrane in conjunction with a differential hydrogen-deuterium exchange (HDX) methodology is described. A non-aqueous (aprotic) matrix was evaluated for use with MALDI sample preparation in order to eliminate undesirable hydrogen-deuterium back-exchange. Peptides and proteins were incubated with liposomes and their penetration into the liposome membrane over time was measured by MALDI-MS. A differential HDX approach was used to distinguish the peptides outside of the liposome from those inside. In this regard, the peptides on the outside of the liposomes were labeled using short exposure to deuterium oxide, while the peptides inside of the liposomes were protected from labeling. Subsequently, the unlabeled versus labeled peak area ratios for peptide and protein samples were compared using MALDI-TOF-MS. In this proof-of-concept study, we developed the Liposome Artificial Membrane Permeability Assay (LAMPA) workflow to study three well-known membrane-active model peptides (melittin, alamethicin, and gramicidin) and two model proteins (aprotinin and ubiquitin). The permeability results obtained from this were corroborated by previously reported data for studied peptides and proteins. The proposed LAMPA by MALDI-HDX-MS can be applied in an ultra-high-throughput manner for studying and rank-ordering membrane permeability of peptides and small proteins.Graphical abstractImage 1
  • A dual-responsive biosensor for blood lead detection
    • Abstract: Publication date: Available online 25 September 2019Source: Analytica Chimica ActaAuthor(s): Huan Chen, Shuibin Shao, Yueqi Yu, Yangyang Huang, Xiaotan Zhu, Shiyan Zhang, Jin Fan, Guo Yong Yin, Bo Chi, Mimi Wan, Chun Mao Simple and accurate detection of trace heavy metals in blood is very important. A novel dual-responsive electrochemical/fluorescent biosensor based on magnetic hyperbranched polyamide with heparin modification (MHPAM-H) for blood lead detection has been successfully developed. Upon conjugated with blood lead ions, dual-biosensor could not only display electrochemical signal but also fluorescence signal owing to the enriched amino groups, cavity structure, and good fluorescence properties of HPAM. Blood biocompatibility, construction of the dual-responsive biosensor, electrochemical/fluorescent detection of lead ions in water phase and blood condition, selectivity and stability of the dual-responsive biosensor were investigated in detail. The proposed dual-responsive biosensor displays good linear relationship (1.5 pM- 4.8×103 pM for electrochemical detection and 0.5 pM-4.8×103 pM for fluorescent detection) with low detection limit (4.4 pM for electrochemical detection and 1.0 pM for fluorescent detection) for blood lead, providing potential application for blood lead detection in the future.Graphical abstractImage 1
  • Towards Early Monitoring of Chemotherapy-induced Drug Resistance Based on
           Single Cell Metabolomics: Combining Single-probe Mass Spectrometry with
           Machine Learning
    • Abstract: Publication date: Available online 25 September 2019Source: Analytica Chimica ActaAuthor(s): Renmeng Liu, Mei Sun, Genwei Zhang, Yunpeng Lan, Zhibo Yang Despite the presence of methods evaluating drug resistance during chemotherapies, techniques, which allow for monitoring the degree of drug resistance in early chemotherapeutic stage from single cells in their native microenvironment, are still absent. Herein, we report an analytical approach that combines single cell mass spectrometry (SCMS) based metabolomics with machine learning (ML) models to address the existing challenges. Metabolomic profiles of live cancer cells (HCT-116) with different levels (i.e., no, low, and high) of chemotherapy-induced drug resistance were measured using the Single-probe SCMS technique. A series of ML models, including random forest (RF), artificial neural network (ANN), and penalized logistic regression (LR), were constructed to predict the degrees of drug resistance of individual cells. A systematic comparison of performance was conducted among multiple models, and the method validation was carried out experimentally. Our results indicate that these ML models, especially the RF model constructed on the obtained SCMS datasets, can rapidly and accurately predict different degrees of drug resistance of live single cells. With such rapid and reliable assessment of drug resistance demonstrated at the single cell level, our method can be potentially employed to evaluate chemotherapeutic efficacy in the clinic.Graphical abstractImage 1
  • Label-assisted chemical adsorption triggered conversion of electroactivity
           of sensing interface to achieve the Ag/AgCl process for ultrasensitive
           detection of CA 19-9
    • Abstract: Publication date: Available online 25 September 2019Source: Analytica Chimica ActaAuthor(s): Nana Zhang, Dongsheng Zhang, Changshun Chu, Zhanfang Ma Efficient strategies in enhancing sensitivity are pivotal to ultrasensitive detection of tumor markers. In this work, based on the strategy of label-assisted chemical adsorption triggered conversion of electroactivity of sensing interface, a Ag/AgCl process was achieved to enhance sensitivity of the constructed sandwich-type amperometric immunosensor for ultrasensitive detection of carbohydrate antigen 19-9 (CA19-9). Briefly, polydopamine-Ag nanoparticles (PDA-Ag NPs), as signal precursor, combined with labeling antibody were served as labels and graphene oxide-melamine (GO-MA) substrate with chemical absorption capacity was applied as smart sensing interface. After successfully incubating labels, there was primitively no current response due to the poor conductivity between labels and electrode. However, in the presence of H2O2, Ag NPs from labels can be etched into Ag ions, which were adsorbed by GO-MA to form GO-MA-Ag as electroactive substrate. Then, the substrate exhibited a sharp and stable electrochemistry peak of solid-state Ag/AgCl process in the buffer containing KCl. The sensitivity toward detection of CA19-9 was notably enhanced based on the appearance of sharp peak. Under optimum conditions, the designed immunosensor demonstrated a wide working range from 0.0001 to 100 U mL-1 and an ultralow detection limit 0.032 mU mL-1. Thus, utilizing this strategy to construct immunosensor was highly promising in clinical diagnosis for ultrasensitive detection of tumor makers.Graphical abstractImage 1
  • High performance tube sensor based on PANI/Eu3+ nanofiber for low-volume
           NH3 detection
    • Abstract: Publication date: Available online 25 September 2019Source: Analytica Chimica ActaAuthor(s): Wenqian Zhang, Guishun Li, Changkun She, Aiyun liu, Jianing Cheng, Hongkai Li, Shaohua Liu, Chengbin Jing, Ya Cheng, Junhao Chu A novel polyaniline (PANI)/Eu3+ nanofiber sensing film was prepared in the presence of Eu(NO3)3 which serves as structure-directed agent. The morphological, component, crystallinity and electrochemical properties were carried out by using Scanning Electron Microscope (SEM), Energy-Dispersive X-ray (EDX), Fourier Transform Infrared spectroscopy (FT-IR), X-Ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) techniques. The results indicated the nanofiber-like network with porous structure appeared in the PANI embedded by Eu3+ ions, thereby leading to large specific surface area. Furthermore, the PANI/Eu3+ nanofibers were grown onto the inner wall of capillary glass to form the tube sensor. By the sensing measurements, this tube sensor enabled the detection of low-volume (0.3 mL) NH3 for response 435% at concentration of 0.25 ppm with a short response time (5 s) and recovery time (5 s), and the performances of reproducibility and selectivity were also excellent. The above results demonstrated the potential application of PANI/Eu3+ tube sensor for low-volume NH3 gas.Graphical abstractImage 1
  • Cobalt-iron selenides embedded in porous carbon nanofibers for
           simultaneous electrochemical detection of trace of hydroquinone, catechol
           and resorcinol
    • Abstract: Publication date: Available online 25 September 2019Source: Analytica Chimica ActaAuthor(s): Duanduan Yin, Jian Liu, Xiangjie Bo, Liping Guo In this study, cobalt-iron selenides embedded in porous carbon nanofibers (CoFe2Se4/PCF), derived from Prussian blue analogues, was prepared as a novel phenolic sensor. The obtained CoFe2Se4/PCF nanocomposites show three-dimensional (3D) networks nanostructures that can supply a desirable conductive network to accelerate electron transfer and avoid the aggregation of CoFe2Se4 nanoparticles. Electrochemical detection of hydroquinone (HQ), catechol (CC) and resorcinol (RS), at CoFe2Se4/PCF modified glassy carbon electrode (GCE) were researched. The results show the obtained 3D CoFe2Se4/PCF/GCE exhibits excellent electrochemical properties towards the simultaneous testing trace of HQ, CC and RS. The obtained electrode provides wide linear ranges of 0.5–200, 0.5–190 and 5–350 μM and low detection limit of 0.13, 0.15 and 1.36 μM for HQ, CC and RS, respectively. The as-prepared phenolic sensor displays satisfied selectivity and long-term storage stability. In addition, the constructed sensor can be used to determine HQ, CC and RS in actual samples.Graphical abstractCoFe2Se4/PCF composites were prepared, which used to simultaneously detect HQ, CC and RS.Image 1
  • Surface molecularly imprinted polymer on magnetic multi-walled carbon
           nanotubes for selective recognition and preconcentration of metformin in
           biological fluids prior to its sensitive chemiluminescence determination:
           Central composite design optimization
    • Abstract: Publication date: Available online 24 September 2019Source: Analytica Chimica ActaAuthor(s): Reza Mohammadi Toudeshki, Shayessteh Dadfarnia, Ali Mohammad Haji Shabani Novel molecularly imprinted polymer (MIP) for metformin was synthesized on the surface of magnetic multi-walled carbon nanotubes (MMWCNTs) as the support. Metformin was used as the template, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker and 2,2'-azoisobutyronitrile (AIBN) as the initiator. The synthesized composite was characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). The surface molecularly imprinted composite was used for magnetic solid phase microextraction (MSPME) of metformin before its chemiluminescence (CL) determination and its capability was compared with non-imprinted polymer (NIP). The central composite design was used for optimization as well as consideration of possible interaction of effective variables on extraction. Under the optimized conditions, the developed method exhibited the linear dynamic range of 0.5-50.0 μg L-1 with a detection limit of 0.13 μg L-1 and enhancement factor of 195.3 for the preconcentration of 100 mL of the sample and 500 μL of an eluent. The intra- and inter-day relative standard deviations (RSD%) at 5.0 μg L-1 level of metformin (n = 6) were 3.7 and 4.9%, respectively. The maximum adsorption capacity of the sorbent was found to be 80.0 mg g-1, the adsorption of metformin was endothermic and spontaneous and followed the Langmuir isotherm model. The adsorption kinetic was also found to be best fitted with the pseudo-second-order model. The designed method was successfully applied to the extraction and determination of metformin in biological fluids and water samples.Graphical abstractImage 1
  • A Ratiometric Fluorescence-scattered Light Strategy Based on MoS2 Quantum
           dots/CoOOH Nanoflakes System for Ascorbic Acid Detection
    • Abstract: Publication date: Available online 24 September 2019Source: Analytica Chimica ActaAuthor(s): Zhihao Wu, Danyang Nan, Huan Yang, Shuang Pan, Hui Liu, Xiaoli HuABSTRACTA facile ratiometric fluorescence method for ascorbic acid (AA) detection was established by combining the fluorescence of MoS2 quantum dots (QDs) with second-order scattering (SOS) of CoOOH. In MoS2 QDs/CoOOH nanohybrid system, the fluorescence of MoS2 QDs was quenched by CoOOH whereas the intensity of SOS was relatively close to the fluorescence due to the intrinsic high scattering ability of large size CoOOH nanoflakes. With the addition of AA, CoOOH nanoflakes were reduced to Co2+ accompanied the size decline and the disappearance of characteristic absorption in UV-vis spectrum, resulting in the fluorescence recovery and SOS fading. Thus, the ratiometric detection of AA was obtained through the opposite changes of fluorescence and SOS. Under optimized conditions, the detection limit of AA was 0.21 μmol L−1 with a linear range from 0.80 to 32.0 μmol L−1. Furthermore, the MoS2 QDs/CoOOH nanohybrid system was applied to the detection of AA in human serum samples and vitamin C tablets with satisfactory results.Graphical abstractScheme 1. Schematic image of ratiometric fluorescence analysis of AA based on MoS2/CoOOH nanohybrids.Image 1
  • Influence of photo-initiators in the preparation of methacrylate monoliths
           into poly(ethylene-co-tetrafluoroethylene) tubing for microbore HPLC
    • Abstract: Publication date: Available online 24 September 2019Source: Analytica Chimica ActaAuthor(s): M. Catalá-Icardo, S. Torres-Cartas, E.F. Simó-Alfonso, J.M. Herrero-Martínez In this study, poly(butyl methacrylate-co-ethyleneglycol dimethacrylate) polymeric monoliths were in situ developed within 0.75 mm i.d. poly(ethylene-co-tetrafluoroethylene) (ETFE) tubing by UV polymerization via three different free-radical initiators (α,α´-azobisisobutyronitrile (AIBN), 2,2-dimethoxy-2-phenylacetophenone (DMPA) and 2-methyl-4´-(methylthio)-2-morpholinopropiophenone (MTMPP). The influence of the nature of each photo-initiator and irradiation time on the morphological features of the polymer was investigated by scanning electron microscopy, and the chromatographic properties of the resulting microbore columns were evaluated using alkyl benzenes as test substances. The beds photo-initiated with MTMPP gave the best performance (minimum plate heights of 38 μm for alkyl benzenes) and exhibited a satisfactory reproducibility in the chromatographic parameters (RSD < 11%). These monolithic columns were also successfully applied to the separation of phenylurea herbicides, proteins and a tryptic digest of β-casein.Graphical abstractImage 1
  • Vacuum-assisted headspace single-drop microextraction: eliminating
           interfacial gas-phase limitations
    • Abstract: Publication date: Available online 24 September 2019Source: Analytica Chimica ActaAuthor(s): Elefteria Psillakis, Niki Koutela, Agustín J. ColussiABSTRACTGas-phase limitations have been neglected in headspace single-drop microextraction (HS-SDME) and rate control has been assumed to primarily reside in the liquid water and/or organic phases, but not in the headspace. Herein we demonstrate the presence of interfacial gas constraints and propose using reduced headspace pressures to remove them. To describe the pressure dependence of HS-SDME, the system was decoupled into two interfacial steps: (i) the evaporation step (water-headspace interface) formulated using the two-film theory and (ii) the analyte uptake by the microdrop (headspace-microdrop interface) formulated using the resistance model. Naphthalene, acenaphthene, and pyrene were chosen as model analytes for their large Henry’s law solubility constants in n-octanol (HOA> 103 M atm-1), and their low to moderate Henry’s law volatility constants in water as a solvent (KH). We have found that extraction times were significantly shortened for all analytes by sampling at pressures well below the 1 atm used in the standard HS-SDME procedure. The acceleration of naphthalene extraction, whose facile evaporation into the headspace had been assumed to be pressure independent, highlighted the role of mass transfer through the interfacial gas layer on the organic solvent drop. The larger accelerations observed for acenaphthene and (especially) pyrene upon reducing the sampling pressure, suggested that gas-sided constraints were important during both the evaporation and uptake steps. Model calculations incorporating mass transfers at the headspace-microdrop interface confirmed that gas-phase resistance is largely eliminated (>96%) when reducing the sampling pressure from 1 to 0.04 atm, an effect that is nearly independent of analyte molecular mass. The relative importance of the two interfacial steps and their gas- and liquid-phase limitations are discussed, next to the use of KH and HOA to predict the positive effect of vacuum on HS-SDME.Graphical abstractImage 1
  • Aptamer recognition and proximity-induced entropy-driven circuit for
           enzyme-free and rapid amplified detection of platelet-derived growth
    • Abstract: Publication date: Available online 23 September 2019Source: Analytica Chimica ActaAuthor(s): Dandan Li, Xinmin Li, Bo Shen, Pu Li, Yuanjiao Chen, Shijia Ding, Weixian Chen Platelet-derived growth factor-BB (PDGF-BB) is currently used as a biomarker protein for cancer early diagnosis and clinical treatment. Herein, we reported a robust and enzyme-free strategy based on aptamer recognition and proximity-induced entropy-driven circuits (AR-PEDC) for homogeneous and rapid detection of platelet-derived growth factor BB (PDGF-BB) without any washing steps or thermocycling. The proximity probes specifically recognize target protein to form the completed trigger (CT). Then, the CT reacts with three-strand complex to form intermediate, which subsequently binds to fuel strand to release reporter strand, assistant strand and the CT. The revised proximity probes exhibit significantly improved signal-to-background ratio and faster association rate. Moreover, target protein/proximity probes interaction can specifically initiate entropy-driven circuits, thus providing immense signal amplification for ultrasensitive detection of PDGF-BB with low detection limit of 9.6 pM. The practical ability of the developed strategy is demonstrated by detection of PDGF-BB in human serum with satisfactory results. In addition, this method is flexible and can be conveniently extended to a variety of targets by simply substituting the target specific sequence. Thus, this strategy presents a rapid, low background and versatile amplification mechanism for the detection of protein biomarkers and offers a promising alternative platform for clinical diagnosis.Graphical abstractImage 1
  • A photostable Si-rhodamine-based near-infrared fluorescent probe for
           monitoring lysosomal pH during heat stroke
    • Abstract: Publication date: Available online 21 September 2019Source: Analytica Chimica ActaAuthor(s): Guo-Jiang Mao, Zhen-Zhen Liang, Guang-Qi Gao, Ying-Ying Wang, Xin-Yu Guo, Li Su, Hua Zhang, Qiu-Juan Ma, Guisheng Zhang Heat stroke is a symptom of hyperthermia with a temperature of more than 40 °C, which usually leads to all kinds of physical discomfort and even death. It is necessary to study the mechanism of action of heat stroke on cells or organelles (such as cytotoxicity of heat) and the processes of cells or organelles during heat stroke. Recent studies have shown that there is a certain correlation between heat stroke and lysosome acidity. In order to clarify their relationship, Lyso-NIR-pH, a photostable Si-rhodamine-based near-infrared fluorescent probe, was developed for sensing pH changes in lysosomes during heat stroke in this paper. For Lyso-NIR-pH, a morpholine group is employed as the lysosome-targeting unit and a H+-triggered openable deoxylactam is employed as the response unit to pH. Lyso-NIR-pH can detect pH with a high selectivity and a sensitivity, and its pKa is 4.63. Lyso-NIR-pH also has outstanding imaging performances, such as excellent lysosome-targeting ability, low autofluorescence and photostable fluorescence signal, which are in favor of long-term imaging of pH with accurate fluorescence signals. Moreover, we successfully applied Lyso-NIR-pH to monitor lysosomal pH increases induced by chloroquine and apoptosis in live cells. Finally, we successfully applied Lyso-NIR-pH for monitoring changes of lysosomal pH during heat stroke. These results confirmed that Lyso-NIR-pH is a powerful tool to monitor pH change in lysosomes and study its possible effects.Graphical abstractImage 1
  • Automated analytical microsystem for the spectrophotometric monitoring of
           titratable acidity in white, rosé and red wines
    • Abstract: Publication date: Available online 20 September 2019Source: Analytica Chimica ActaAuthor(s): Natàlia Sández, Antonio Calvo-López, Susana S.M.P. Vidigal, António O.S. S. Rangel, Julián Alonso-Chamarro The design, construction and evaluation of a low-cost cyclic olefin copolymer (COC)-based continuous flow microanalyzer with optical detection to determine the titratable acidity content of wine is here presented. The analysis method is based on the monitoring of the blue coloration decrease of a buffered bromothymol blue (BTB) solution in the presence of the acidic compounds of wine. The microanalyzer monolithically integrates the required microfluidic motifs as well as an optical flow cell where the measurements are performed by using a miniaturized and versatile photometric detection system.Fluid management is totally automated by the use of computer-controlled microvalves, permitting the automatic calibration of the system as well as the automatic sampling, including in-line dilution and analysis. The reduced size of the whole system along with its high simplicity and automation make it suitable for its application to the on-line monitoring of titratable acidity during wine-making processes.With the optimal conditions, a linear range up to 0.50 g L-1 tartaric acid, a quantification limit (LOQ) of 0.01 g L-1 and a detection limit (LOD) of 0.004 g L-1 were obtained, covering the most common acidity content of musts and wines. A sampling rate up to 26 h-1 could be achieved, consuming less than 3 mL of inexpensive reagents per analysis and requiring no pretreatment of the sample. The microsystem has been successfully applied to the quantification of the titratable acidity content of several wine samples, being the results in excellent agreement with the ones obtained by the reference method.Graphical abstractImage 1
  • Simple and accurate visual detection of single nucleotide polymorphism
           based on colloidal gold nucleic acid strip biosensor and primer-specific
    • Abstract: Publication date: Available online 20 September 2019Source: Analytica Chimica ActaAuthor(s): Hai-Bo Wang, Li-Hong Ma, Ting Zhang, Kai-Chen Huang, Yuan-Di Zhao, Tian-Cai Liu Single nucleotide polymorphism (SNP) was associated with many human diseases, therefore, SNP detection was important for early diagnosis and clinical prognosis. Herein, a simple and accurate method for visual detection SNP sites (A/A, G/G, A/G) in CYP1A1 gene related to cancers based on colloidal gold nucleic acid strip biosensor and primer-specific polymerase chain reaction (PCR) was established. This method could directly distinguish SNP sites on strip biosensor by introducing twice PCR amplifications. The second PCR (primer-specific PCR) was performed using specific product of the first PCR as template, thus this twice PCR could reduce non-specific amplification greatly and obtain target product. In addition, single-strand or double-strand DNA (ssDNA or dsDNA) was accurately produced by introducing mismatched base at the 3’ end of forward primers in primer-specific PCR. The designed strip biosensor could only combine with the ssDNA, thus visual detection of SNP could be achieved within 10 min by color difference of a pair of strips. 61 human blood samples by this method were identical with those of pyrosequencing. This method had the advantages of rapid, visual and low-cost and was expected to be applied in medical diagnosis.Graphical abstractImage 1
  • Sensitive monitoring and bioimaging intracellular highly reactive oxygen
           species based on gold nanoclusters@nanoscale metal-organic frameworks
    • Abstract: Publication date: Available online 20 September 2019Source: Analytica Chimica ActaAuthor(s): Xuanyu Cao, Shasha Cheng, Yi You, Shiming Zhang, Yuezhong Xian Nanoscale metal-organic frameworks (NMOFs) have been widely employed in biological diagnosis and treatment system. In this work, glutathione stabilized gold nanoclusters (GSH-AuNCs) were successfully encapsulated in NMOFs and the as-obtained nanocomposites (named as AuNCs@NMOFs) showed nearly 10 times enhancement in fluorescence intensity and longer fluorescence lifetime relative to GSH-AuNCs. In addition, the fluorescence intensity of AuNCs@NMOFs was quenched by highly reactive oxygen species (hROS) due to their strong oxidation ability. Based on the fact, the nanocomposites were used for the detection of hROS with a linear range from 80 nM to 1.0 μM toward hypochlorite (as the representative of hROS). The limit of detection (LOD) was about 30 nM, which was about 30 times lower than that of GSH-AuNCs (LOD=0.96 μM). With the features of good biocompatibility, excellent luminescence and efficient cellular uptake, AuNCs@NMOFs were successfully applied in fluorescence imaging of hROS in living cells.Graphical abstractAu nanoclusters@NMOF nanocomposites were prepared and further applied for hROS detection with high sensitivity in living cells.Image 1
  • The multiple facets of flow analysis. A tutorial
    • Abstract: Publication date: Available online 20 September 2019Source: Analytica Chimica ActaAuthor(s): Elias A.G. Zagatto, Fábio R.P. Rocha The amazing development of flow analysis has led to a loss of conceptual uniformity and to the proposals of a number of modalities, each assigned to an acronym, however this aspect may hinder further developments in the field. As any sample handling step of a flow-based analytical procedure can be accomplished in different ways, there are multiple facets associated to it. This tutorial is focused on the critical evaluation of these facets and the proposal of a novel way to present the flow analyzers, disregarding or even avoiding the need for specifying flow modalities and acronyms.Graphical abstractImage 1
  • Sensitive determination of the human epidermal growth factor receptor 2
           (HER2) by immuno-polymerase chain reaction with inductively coupled
           plasma-mass spectrometry detection
    • Abstract: Publication date: Available online 19 September 2019Source: Analytica Chimica ActaAuthor(s): A.Fernández Asensio, L.M. Sierra, M. Montes-Bayón, E. Blanco-González Sensitive and selective analytical methods are necessary for the determination of clinical biomarkers of breast cancer. The human epidermal growth factor receptor 2 (HER2) is an important breast cancer biomarker since tumors with HER2 protein overexpression (HER2-positive tumors) turn out to be more aggressive and likely to recur. Therefore, accurate determination of serum HER2 values is critical to optimize clinical outcomes in patients with breast cancer. To gain sensitivity and selectivity in the determination of HER2, a sandwich immune assay (highly selective) has been implemented using a detection antibody labelled with a DNA marker. Further amplification of the label using the polymerase chain reaction (PCR), followed by phosphorous quantification of the PCR product (amplicon) using inductively coupled plasma mass spectrometry (ICP-MS), completes this novel assay. Considering that the concentration of the amplicon is proportional to the amount of antigen (HER2) that is recognized by the labelled detection antibody, the concentration of HER2 can be directly obtained by P-analysis. For this aim, a DNA marker of 123 base pairs has been connected to the detection antibody of a sandwich immune assay conducted in pre-coated plates containing the capture antibody of HER2. After the recognition occurred, the PCR amplification was conducted and the PCR product analysed by ICP-MS. Detection limits of 2.5 pg. mL-1 of HER2 could be achieved using 35 PCR cycles (7-fold lower than the commercial ELISA method). The developed methodology has been applied to the determination of HER2 in biological samples (human serum and cell culture supernatant of breast cancer cells, MDA-MB-231) obtaining mean method recoveries of about 87% and 81%, respectively.Graphical abstractImage 1
  • QTR-FRET: Efficient Background Reduction Technology in Time-Resolved
           Förster Resonance Energy Transfer Assays
    • Abstract: Publication date: Available online 19 September 2019Source: Analytica Chimica ActaAuthor(s): Markku Syrjänpää, Emmiliisa Vuorinen, Sakari Kulmala, Qi Wang, Harri Härmä, Kari Kopra A novel homogeneous assay system QTR-FRET (Quencher modulated Time-Resolved Förster Resonance Energy Transfer) combining quenching resonance energy transfer (QRET) and time-resolved Förster resonance energy transfer (TR-FRET) was developed to reduce background signal in the conventional energy transfer applications. The TR-FRET functionality is often limited by the lanthanide donor background signal leading to the use of low donor concentration. QTR-FRET reduces this background by introducing soluble quencher molecule, and in this work the concept functionality was proven and compared to previously introduced QRET and TR-FRET technologies. Comparison was performed with three different Eu3+-chelates exhibiting different luminescent lifetime and stability. The side-by-side comparison of the three signaling systems and Eu3+-chelates was demonstrated in a model assay with Eu3+-chelate conjugated biotin and streptavidin (SA) or Cy5-SA conjugate. Comparison of the methodologies showed increased signal-to-background ratios when comparing QTR-FRET to TR-FRET, especially at high Eu3+-biotin concentrations. Quenching the non-bound Eu3+-biotin improved the assay performance, which suggests that an improved assay performance can be attained with the QTR-FRET method. QTR-FRET is expected to be especially useful for Eu3+-labeled ligands with low affinity or assays requiring high Eu3+-ligand concentration. The QTR-FRET indicated potential for multi-analyte approaches separately utilizing the direct QRET-type Eu3+-chelate signal and energy transfer signal readout in a single-well. This potential was hypothesized with Avi-KRAS nucleotide exchange assay as a second biologically relevant model system.Graphical abstractImage 1
  • Exploring the upper particle size limit for field flow fractionation
           online with ICP-MS to address the challenges of water samples from the
           Taihu Lake
    • Abstract: Publication date: Available online 19 September 2019Source: Analytica Chimica ActaAuthor(s): Jingjing Yang, Ping Tan, Tianyin Huang, Volker Nischwitz Regular algal blooms are occurring in Taihu lake, which may be triggered by resuspension of sediments containing relevant amounts of phosphorus. Therefore, our study aims at quantification of phosphorus concentrations bound to suspended particulate matter in Taihu water samples to investigate this hypothesis. A field flow fractionation (FFF) method online with ICP-MS detection was developed to achieve an overview on particulate fractions of phosphorus and related elements including Fe, Al and C from the low nanometer to the low micrometer size range. Mass balance of dissolved and particulate elemental contents was established for quality control purpose and indicated low recovery of Fe, Al and P. Complementary determination of volume based particle size distribution by dynamic imaging analysis showed a majority of particle volume and thus mass in particles with size>5 μm. In order to address this challenge, the upper particle size limit of FFF online with ICP-MS was for the first time investigated in detail using well characterised monodisperse latex particles as model for organic matter in the low micrometer size range including microalgae. The effect of pre-filtration of the sample as well as the contribution of sample introduction via three different interfaces including micromist nebuliser/spray chamber, direct injection nebulisation and APEX with heated spray chamber and solvent removal by condensation on the particulate carbon recovery was studied by ICP-MS detection. The same instrumental setup was also applied for the characterisation of particulate elemental contents in the Taihu water samples as far as possible. Significant improvement of the detected particulate fraction in Taihu water samples was achieved by increasing the membrane pore size for pre-filtration and by using the APEX for introduction of the eluate from FFF into ICP-MS.Graphical abstractImage 1
  • Glassy Carbon Electrodes Modified with Reduced Graphene Oxide-MoS2-Poly
           (3, 4-Ethylene Dioxythiophene) Nanocomposites for the Non-Enzymatic
           Detection of Nitrite in Water and Milk
    • Abstract: Publication date: Available online 19 September 2019Source: Analytica Chimica ActaAuthor(s): Rajesh Madhuvilakku, Srinivasan Alagar, Ramalakshmi Mariappan, Shakkthivel Piraman The detrimental effect of (NO2-) on environment, a sensitive and selective detection of nitrite (NO2-) ions with point-to-care device is needed to be fabricated. Herein, we report the non-enzymatic nitrite sensor using a novel reduced graphene oxide/molybdenum disulfide/poly (3, 4-ethylene dioxythiophene) (rGO/MoS2/PEDOT) nanocomposite electrode. The rGO/MoS2/PEDOT nanocomposite was synthesized using facile and cost-effective hydrothermal and polymerization approaches. The characteristics of rGO-MoS2-PEDOT nanocomposite was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Brunauer-Emmett-Teller (BET) analyses. The rGO-MoS2-PEDOT nanocomposite modified glassy carbon electrode (GCE) was directly used for electrocatalytic detection of nitrite ions present in the solution. TEM images show the PEDOT nanoparticles with an average size of 100-120 nm are uniformly covered on the outer face of rGO-MoS2 nanosheets. The interaction between the PEDOT and rGO-MoS2 is evidenced in the FTIR, XRD and XPS studies, and they produced synergistic effect and resulting enhanced electrocatalytic performance activity towards oxidation of nitrite. Under optimized conditions, the fabricated electrode exhibited remarkably good sensitivity (874.19 μA μM-1 cm-2), low detection limit (LOD) (0.059 μM, S/N =3), wide linear range (0.001-1mM) of nitrite with desirable selectivity, long-term stability and reproducibility. Furthermore, the practical feasibility of the fabricated sensor is validated by the successful detection of nitrite ion in some water and milk samples with excellent correlation. Thus, feasible easier synthesis method was adopted first time to fabricate rGO-MoS2-PEDOT nanocomposite nitrite sensor in the milk and water samples with enhanced selectivity, sensitivity and LOD.Graphical abstractImage 1
  • Automatic Soft Independent Modeling for Class Analogies
    • Abstract: Publication date: Available online 18 September 2019Source: Analytica Chimica ActaAuthor(s): Zewei Chen, Peter de Boves Harrington Soft independent modeling of class analogy (SIMCA) is an important method for authentication. The key parameters for SIMCA, the number of principal components and decision threshold, determine the model’s performance. In this report, a self-optimizing SIMCA that automatically determines these two parameters is devised and referred to as automatic SIMCA (aSIMCA). An efficient optimization is obtained by incorporating response surface modeling and bootstrapped Latin partitions with the model-building dataset. A set of design points over the ranges of the two parameters are evaluated with respect to sensitivity and specificity by using model-building data from target and non-target classes. Averages of sensitivity and specificity are used as responses for the design points. A 2-dimensional interpolation and a bivariate cubic polynomial were used to model the response surface. As a control method, a grid search that evaluates all combinations of the two parameters over the same ranges was performed in parallel to determine the best conditions for SIMCA and the modeling performance was compared to aSIMCA with RSM. The developed aSIMCA methods were evaluated by authenticating two botanical extracts sets, i.e., marijuana and hemp, with spectral datasets collected from various spectroscopic techniques, including nuclear magnetic resonance, high-resolution mass, and ultraviolet spectrometry. Results of a paired t-test indicated that the aSIMCA with the RSM had similar performance with the one optimized by the grid search for modeling marijuana and hemp, while the RSM was more computationally efficient. The 2-dimensinal interpolation is preferred because the better efficiency and the fit to the response surface is more precise.Graphical abstractImage 1
  • Quantitative response in ion mobility spectrometry with atmospheric
           pressure chemical ionization in positive polarity as a function of
           moisture and temperature
    • Abstract: Publication date: Available online 17 September 2019Source: Analytica Chimica ActaAuthor(s): Zahra Safaei, Timothy J. Willy, Gary A. Eiceman, J.A. Stone, M. Sillanpää Response of an ion mobility spectrometer at ambient pressure was quantitatively determined for fourteen chemicals from five chemical families spanning a range of proton affinities and temperature from 30 to 175 °C with moisture from 1 to 1 × 104 ppmv in purified air. Peak intensities, drift times and reduced mobility coefficients were determined for hydrated protons from a63Ni ion source and for protonated monomers and proton bound dimers of alcohols, aldehydes, acetates, ketones, and organophosphates. These measurements permitted the determination of response factors with atmospheric pressure chemical ionization and the influence of moisture and temperature on APCI response with correlation to computational models of hydration values. The formation of protonated monomers and proton bound dimers was described by heats of formation for a displacement reaction of water on H+(H2O)n by an analyte vapor and favorably matched results from density functional theory (DFT) with the 6-311 + G(dp) basis set. Response factors worsened with increased moisture and decreased temperature for compounds of medium, and more so, of low proton affinities. Findings here provide a broad measure and understanding for quantitative response in ion mobility spectrometers for substances for combinations of moisture and temperature.Graphical abstractImage 1
  • Magnetism-reinforced in-tube solid phase microextraction for the online
           determination of trace heavy metal ions in complex samples
    • Abstract: Publication date: Available online 17 September 2019Source: Analytica Chimica ActaAuthor(s): Meng Mei, Jinling Pang, Xiaojia Huang, Qing Luo For the first time, a convenient, online couplable, sensitive and environmentally friendly sample pretreatment method, namely, magnetism-reinforced in-tube solid phase microextraction (MR/IT-SPME) was proposed to effectively enrich heavy metal ions (HMIs). Monolithic capillary microextraction column embedded modified Fe3O4 magnetic nanoparticles (MCEN) was conveniently synthesized and employed as the microextraction column of MR/IT-SPME. Subsequently, the MCEN was put into a magnetic coil which was utilized to exert variable magnetic field during extraction procedure. Three HMIs, including Cu(II), Co(II) and Hg(II), were selected as studied ions and reacted with chelating agent sodium diethyldithiocarbamatetrihydrate to form metallic coordination compounds. The complexes were infused to the MCEN to perform the MR/IT-SPME extraction and then online determined by high-performance liquid chromatography equipped with diode array detection (HPLC-DAD). A series of key parameters affecting the extraction performance were investigated in detail. Results revealed that the exertion of magnetic field in adsorption and desorption steps favored the adsorption and release of the coordination compounds, with the extraction efficiencies enhanced from 47-65% to 67-89%. Finally, the developed online MR/IT-SPME-HPLC-DAD approach was successfully applied to determine studied HMIs in environmental water and seafood samples. The confirmatory experiments further evidenced the reliability and feasibility of the introduced approach for the analysis of trace HMIs in complex samples.Graphical abstractImage 1
  • Using PbS-Au heterodimers as signal quencher for the sensitive
           photoelectrochemical immunoassay of amyloid β-protein
    • Abstract: Publication date: Available online 16 September 2019Source: Analytica Chimica ActaAuthor(s): Qingzhi Han, Huitong Chi, Hanyu Wang, Dan Wu, Qin Wei By using PbS-Au heterodimers as the signal quencher, TiO2/BiOI as matrix, a novel sandwich-type photoeletrochemical (PEC) biosensor for sensitive determination of amyloid β-protein (Aβ, ∼ 4 KDa) was developed. BiOI was attached to the surface of TiO2 and formed a heterogeneous structure (p-n junction), which enlarged the light harvest range and enhanced the electron transfer rate of TiO2. In order to quench the PEC signal, PbS-Au heterodimers were used as the labels to combine with Aβ. Owing to the competitively light energy harvesting and electron donor consuming effect of PbS-Au heterodimers, less light energy and electron donor arrived at TiO2/BiOI. In addition, Au directly contacted with PbS could enhance the electron seperation and transfer rate, and lead to improved competitiveness consumption of the electron donor. PbS-Au integrated with secondary antibodies formed PbS-Au-Ab2 bioconjugate, which would further obstruct the electron transfer and impede the interreaction between electron donor and photoelectrode surfaces. Owing to the unique PbS-Au heterodimer structure and the quenching effect of PbS-Au-Ab2 bioconjugate, the fabricated immunosensor for Aβ detection exhibited good stability, high sensitivity, and a low detection limit of 0.028 pg/mL (S/N = 3).Graphical abstractImage 1
  • An enzyme-free electrochemical biosensor for simultaneous detection of two
           hemophilia A biomarkers: combining target recycling with quantum
           dots-encapsulated metal-organic frameworks for signal amplification
    • Abstract: Publication date: Available online 16 September 2019Source: Analytica Chimica ActaAuthor(s): H. Rezaei, M. Motovali-bashi, S. Radfar A sensitive and selective electrochemical method for simultaneous detection of two hemophilia A-related microRNAs (miR-1246 and miR-4521) was developed. This detection tactic was based on gold nanoparticles (AuNPs), heavy metals quantum dots-encapsulated metal-organic frameworks (QDs@ZIF-8), and catalytic hairpin assembly (CHA) for signal application. Primarily, hairpins H1 and H2 were hybridized with targets miR-1246 (T1) and miR-4521 (T2) for forming H1-T1 and H2-T2 duplex stranded DNAs (dsDNAs) that were able to open the hairpins H3 and H4 for the formation of H1-H3 and H2-H4 dsDNAs. Meanwhile, lots of H1-H3 and H2-H4 dsDNAs were created by releasing the target to take part in the next cycle for signal amplification. And then single stranded fragments of H1-H3 and H2-H4 dsDNAs were utilized for hybridizing the PbS@ZIF-8-S1 and CdS@ZIF-8-S2 in order to amplify the electrochemical signal. The diagnosis of corresponding target miRs using differential pulse voltammetry has been possible by releasing Pb (II) and Cd (II) ions from PbS@ZIF-8 and CdS@ZIF-8 tags by HCI leaching. In this context, encapsulation of heavy metals quantum dots (QDs) was done in zeolitic imidazolate framework-8 (ZIF-8) to form QDs@ZIF-8 muti-core-shell particles by in situ growth of ZIF-8 in the presence of QDs. Since the quantity of QDs tagged to each target miRs grows massively, being resulted from a huge number of QDs that encapsulated in each QDs@ZIF-8 label, the sensitivity of the biosensor using QDs@ZIF-8 particles as signal tags is about 15 times that of a biosensor using QDs as signal tags. Several conditions of determination like incubation time for labeling and capture probe, HCl leaching time, and reaction time of CHA were optimized. Under the optimized conditions, this assay allowed the detection of target miRs in the range of 1 fM to 1μM with detection limits of 0.19 fM and 0.28 fM for miR-1246 and miR-4521 (S/N = 3). The biosensor can discriminate complementary, 1-base mismatched and non-complementary sequences quite well, according to the catalytic hairpin assembly. Furthermore, the biosensor was utilized efficiently for quick and direct analysis of microRNAs in human serum. Thus, this tactic presents an innovative platform for microRNAs expression profiling in biomedical research and clinical diagnosis.Graphical abstractImage 1
  • A microfluidic colorimetric immunoassay for sensitive detection of
           altenariol monomethyl ether by UV spectroscopy and smart phone imaging
    • Abstract: Publication date: Available online 16 September 2019Source: Analytica Chimica ActaAuthor(s): Yan Man, An Li, Bingru Li, Jing Liu, Ligang Pan A novel microfluidic colorimetric immunoassay was developed using gold nanoparticles (GNPs) for indicating different concentrations of altenariol monomethyl ether (AME), and UV spectroscopy and smart phone imaging for monitoring color change of the GNPs. Norland Optical Adhesive 81 (NOA 81) was used for simple and rapid fabrication of the microfluidic chip. AME-BSA modified magnetic nanoparticles (MNPs-BSA-AME) were used as capture probe and the self-magnetism for rapid separation and purification. AME monoclonal antibodies modified gold nanoparticles (GNP-mAbs) which dried on conjugate pad were used as detection probe and the self-catalyst for signal amplification. Under the optimal conditions, the proposed microfluidic colorimetric immunoassay was able to detect AME as low as 12.5 pg/mL for UV spectroscopy (574 nm), and 200 pg/mL for smart phone imaging. The total analysis time is less than 15 min. The immunoassay also has a lower cross-reactivity to AME analogues. It was also evaluated by analyzing fruit samples spiked with AME. The recoveries ranged from 91.19% to 94.15% for UV spectroscopy, and from 90.63% to 93.9% for smart phone imaging. This method can be used for rapid, sensitive, low-cost and portable point-of care testing (POCT) of other mycotoxins or haptens in food samples.Graphical abstractImage 1
    • Abstract: Publication date: Available online 16 September 2019Source: Analytica Chimica ActaAuthor(s): Olaya Amor-Gutiérrez, Estefanía Costa-Rama, Noemi Arce-Varas, Carmen Martínez-Rodríguez, Antonello Novelli, María Teresa Fernández-Sánchez, Agustín Costa-García Alzheimer’s disease is one of the most common causes of dementia nowadays, and its prevalence increases over time. Because of this, accurate methods for the analysis of specific biomarkers for an early diagnosis of this disease are much needed. Recently, the levels of unfolded isoform of the multifunctional protein p53 in plasma have been proved to increase selectively in Alzheimer’s Disease patients in comparison with healthy subjects, thus entering the list of biomarkers that can be used for the diagnosis of this illness.We present here the development of an electrochemical immunosensor based on nanostructured screen-printed carbon electrodes for the quantification of unfolded p53 in plasma samples. The sensor shows a suitable linear range (from 2 to 50 nM) for its application in real blood samples and a very low limit of detection (0.05 nM). The concentration of unfolded p53 has been accurately detected in plasma of elderly people in healthy conditions, subjects with mild cognitive impairment (MCI) and Alzheimer’s Disease (AD) subjects, obtaining results with no significant differences to those provided by an ELISA assay. This result supports the possibility of measuring unfolded p53 levels with a cheap, simple and miniaturized device with a promising future for point-of-care applications in the early diagnosis of Alzheimer’s dementia.Graphical abstractImage 1
  • Cascade signal amplification sensing strategy for highly specific and
           sensitive detection of homologous microRNAs in different molecular
           subtypes of breast cancer
    • Abstract: Publication date: Available online 16 September 2019Source: Analytica Chimica ActaAuthor(s): Ling Qiao, Chuanli Wu, Zhewei Cai, Xingchen Wu, Ping Wu, Chenxin Cai Discriminative identification of homologous miRNAs in miRNA family with high specificity and sensitivity is crucial for accurate classification, diagnosis and prognosis of breast cancer. Herein, we report a reliable, sensitive, and selective assay by coupling fluorescence resonance energy transfer (FRET) with cascade signal amplification. The strategy is developed by designing two programmable DNA probes that can be triggered to shift from “off” to “on” state in a cascade hybridization reaction in the presence of target miRNA let-7a, leading to the generation of an amplified signal. The assay can detect concentrations as low as ∼3.0 pM let-7a and discriminate let-7a from other highly homologous members in the let-7 miRNA family. Moreover, it can also be used to determine let-7a levels at single-cell resolution and evaluate the drug efficacy of let-7a expression among various molecular types of breast cancer cell lines. The advantage of this assay is a combined result of signal generation and amplification triggered by target miRNA, which can satisfy an assay of analogous miRNA in a downregulated manner with high specificity. It has promising potential as a selective assay for homologous miRNAs in precision medicine.Graphical abstractImage 1
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Heriot-Watt University
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