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Publisher: Elsevier   (Total: 3123 journals)

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Showing 1 - 200 of 3120 Journals sorted alphabetically
A Practical Logic of Cognitive Systems     Full-text available via subscription   (Followers: 8)
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 26, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 22, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 90, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 25, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 30, SJR: 2.515, h-index: 90)
Achievements in the Life Sciences     Open Access   (Followers: 4)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 5, SJR: 0.338, h-index: 19)
Acta Astronautica     Hybrid Journal   (Followers: 379, SJR: 0.726, h-index: 43)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Biomaterialia     Hybrid Journal   (Followers: 26, SJR: 2.02, h-index: 104)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 1)
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 8, SJR: 0.172, h-index: 29)
Acta Haematologica Polonica     Free   (Followers: 1, SJR: 0.123, h-index: 8)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.604, h-index: 38)
Acta Materialia     Hybrid Journal   (Followers: 237, SJR: 3.683, h-index: 202)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.615, h-index: 21)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.442, h-index: 21)
Acta Oecologica     Hybrid Journal   (Followers: 10, SJR: 0.915, h-index: 53)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription   (Followers: 1)
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 3, SJR: 0.311, h-index: 16)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 25, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.059, h-index: 77)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 4)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 3)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 4, SJR: 0.383, h-index: 19)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 2)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 5, SJR: 0.141, h-index: 3)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 4, SJR: 0.112, h-index: 2)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 5)
Acute Pain     Full-text available via subscription   (Followers: 13)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.967, h-index: 57)
Addictive Behaviors     Hybrid Journal   (Followers: 15, SJR: 1.514, h-index: 92)
Addictive Behaviors Reports     Open Access   (Followers: 7)
Additive Manufacturing     Hybrid Journal   (Followers: 7, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Advanced Cement Based Materials     Full-text available via subscription   (Followers: 3)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 139, SJR: 5.2, h-index: 222)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.265, h-index: 53)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.739, h-index: 33)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.299, h-index: 15)
Advances in Agronomy     Full-text available via subscription   (Followers: 15, SJR: 2.071, h-index: 82)
Advances in Anesthesia     Full-text available via subscription   (Followers: 27, SJR: 0.169, h-index: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 4)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 9, SJR: 1.054, h-index: 35)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 12, SJR: 0.801, h-index: 26)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 23, SJR: 1.286, h-index: 49)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 16, SJR: 3.31, h-index: 42)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.277, h-index: 43)
Advances in Botanical Research     Full-text available via subscription   (Followers: 3, SJR: 0.619, h-index: 48)
Advances in Cancer Research     Full-text available via subscription   (Followers: 26, SJR: 2.215, h-index: 78)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 0.9, h-index: 30)
Advances in Catalysis     Full-text available via subscription   (Followers: 6, SJR: 2.139, h-index: 42)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 4)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 13)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 26, SJR: 0.183, h-index: 23)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.665, h-index: 29)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 9, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 29, SJR: 0.938, h-index: 33)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18, SJR: 2.314, h-index: 130)
Advances in Computers     Full-text available via subscription   (Followers: 16, SJR: 0.223, h-index: 22)
Advances in Dermatology     Full-text available via subscription   (Followers: 12)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 12)
Advances in Digestive Medicine     Open Access   (Followers: 7)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 6)
Advances in Drug Research     Full-text available via subscription   (Followers: 23)
Advances in Ecological Research     Full-text available via subscription   (Followers: 47, SJR: 3.25, h-index: 43)
Advances in Engineering Software     Hybrid Journal   (Followers: 27, SJR: 0.486, h-index: 10)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 9)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 46, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 52, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Genetics     Full-text available via subscription   (Followers: 17, SJR: 2.558, h-index: 54)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 2.325, h-index: 20)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 0.497, h-index: 31)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 27)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.396, h-index: 27)
Advances in Immunology     Full-text available via subscription   (Followers: 36, SJR: 4.152, h-index: 85)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 1.132, h-index: 42)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 3, SJR: 1.274, h-index: 27)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 4)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.764, h-index: 15)
Advances in Lipobiology     Full-text available via subscription   (Followers: 2)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 10)
Advances in Marine Biology     Full-text available via subscription   (Followers: 16, SJR: 1.645, h-index: 45)
Advances in Mathematics     Full-text available via subscription   (Followers: 10, SJR: 3.261, h-index: 65)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6, SJR: 0.489, h-index: 25)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 5, SJR: 1.44, h-index: 51)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 23)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 10)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 9, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 4)
Advances in Oncobiology     Full-text available via subscription   (Followers: 2)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15, SJR: 2.885, h-index: 45)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.148, h-index: 11)
Advances in Parasitology     Full-text available via subscription   (Followers: 7, SJR: 2.37, h-index: 73)
Advances in Pediatrics     Full-text available via subscription   (Followers: 24, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 13)
Advances in Pharmacology     Full-text available via subscription   (Followers: 16, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.384, h-index: 26)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.248, h-index: 11)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 7)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 1.5, h-index: 62)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.478, h-index: 32)
Advances in Radiation Oncology     Open Access  
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.1, h-index: 2)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 5)
Advances in Space Research     Full-text available via subscription   (Followers: 370, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 8)
Advances in Surgery     Full-text available via subscription   (Followers: 9, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 31, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 16)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 6, SJR: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 45, SJR: 2.408, h-index: 94)
Aeolian Research     Hybrid Journal   (Followers: 5, SJR: 0.973, h-index: 22)
Aerospace Science and Technology     Hybrid Journal   (Followers: 338, SJR: 0.816, h-index: 49)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.318, h-index: 36)
African J. of Emergency Medicine     Open Access   (Followers: 6, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 9, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 432, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 15, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 31, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 42, SJR: 1.546, h-index: 79)
Agriculture and Agricultural Science Procedia     Open Access  
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 56, SJR: 1.879, h-index: 120)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.434, h-index: 14)
Air Medical J.     Hybrid Journal   (Followers: 5, SJR: 0.234, h-index: 18)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.285, h-index: 3)
Alcohol     Hybrid Journal   (Followers: 11, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 8)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.436, h-index: 12)
Alexandria J. of Medicine     Open Access   (Followers: 1)
Algal Research     Partially Free   (Followers: 9, SJR: 2.05, h-index: 20)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.46, h-index: 29)
Allergology Intl.     Open Access   (Followers: 4, SJR: 0.776, h-index: 35)
Alpha Omegan     Full-text available via subscription   (SJR: 0.121, h-index: 9)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 9, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 49, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 4)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 48, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 48, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 42, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 9, SJR: 1.091, h-index: 45)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.653, h-index: 93)
American J. of Human Genetics     Hybrid Journal   (Followers: 32, SJR: 8.769, h-index: 256)
American J. of Infection Control     Hybrid Journal   (Followers: 26, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 31, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 45, SJR: 2.023, h-index: 189)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 208, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 61, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 6)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.249, h-index: 88)
American J. of Otolaryngology     Hybrid Journal   (Followers: 24, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 27, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 26, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 36, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.653, h-index: 70)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 6)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.066, h-index: 51)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 60, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 14)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 2, SJR: 0.209, h-index: 27)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription   (SJR: 0.104, h-index: 3)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 4, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 36, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 171, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 8, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 12)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 1)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 22, SJR: 0.421, h-index: 40)
Angiología     Full-text available via subscription   (SJR: 0.124, h-index: 9)
Angiologia e Cirurgia Vascular     Open Access  
Animal Behaviour     Hybrid Journal   (Followers: 176, SJR: 1.907, h-index: 126)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 5, SJR: 1.151, h-index: 83)

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Journal Cover Analytica Chimica Acta
  [SJR: 1.548]   [H-I: 152]   [36 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0003-2670 - ISSN (Online) 1873-4324
   Published by Elsevier Homepage  [3123 journals]
  • Quantitative and rapid detection of C-reactive protein using quantum
           dot-based lateral flow test strip
    • Authors: Ruili Wu; Shuai Zhou; Ting Chen; Jinjie Li; Huaibin Shen; Yujuan Chai; Lin Song Li
      Pages: 1 - 7
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Ruili Wu, Shuai Zhou, Ting Chen, Jinjie Li, Huaibin Shen, Yujuan Chai, Lin Song Li
      A novel QD-based immunoassay on a paper-based lateral flow system has been developed to quantitatively detect C-reactive protein (CRP). Different standard CRP antigens from 1 to 200 μg mL−1 were diluted 200-fold and only 60 μL diluted sample were needed to load onto the sample pad. The QD fluorescence signals on the test line and the control line were able to be observed within 3 min after the initiation of assay, and the limit of detection was as sensitive as 0.30 ng mL−1 by measuring the fluorescence intensity immediately afterwards with fluorescence immunoassay analyzer. The linearity on the detection of QD fluorescence signals has been established well in the range of 0.5 ng mL−1 and 1 μg mL−1 for CRP. The precision of the assay has been confirmed for low coefficient of variation (CV), satisfying less than 15% (intra-assay and inter-assay), and the accuracy of assay meets the requirements with the mean recovery of the control was 102.63%. These results indicated that such newly developed platform was reliable with high sensitivity, rapidness, and could cover a broad range of target concentrations. Furthermore, a total of 135 human serum clinical samples with inflammation or infection with the concentration of CRP from 0.2 to 200 μg mL−1 has been used to check the performance of this QD-based LFIA, it correlated very well with Roche Tina-quant CRP (Latex) (r = 0.966, n = 135).
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.031
      Issue No: Vol. 1008 (2018)
       
  • Investigation of hydride generation from arsenosugars - Is it feasible for
           speciation analysis'
    • Authors: Karel Marschner; Stanislav Musil; Ivan Mikšík; Jiří Dědina
      Pages: 8 - 17
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Karel Marschner, Stanislav Musil, Ivan Mikšík, Jiří Dědina
      Hydride generation (HG) from arsenosugars (dimethylarsinoylribosides) in batch and flow injection modes was studied. Its efficiency was found higher in H2SO4 medium than in HCl and higher in the batch mode than in the flow injection mode. To increase the efficiency in the flow injection mode a new generator with two inlets of NaBH4 solution was designed. This modified generator was interfaced between a HPLC column and an atomic fluorescence detector. The arsenosugars studied yielded HG efficiencies in the range 13–30% most probably due to a complicated mechanism of HG. While the mechanism included a formation of two structures of the analyte-borane-complexes, only one of them can lead to a formation of volatile arsanes (dimethylarsane, methylarsane, and arsane were identified).
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2018.01.009
      Issue No: Vol. 1008 (2018)
       
  • Triethylamine-assisted Mg(OH)2 coprecipitation/preconcentration for
           determination of trace metals and rare earth elements in seawater by
           inductively coupled plasma mass spectrometry (ICP-MS)
    • Authors: Zikri Arslan; Tulay Oymak; Jeremy White
      Pages: 18 - 28
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Zikri Arslan, Tulay Oymak, Jeremy White
      In this paper, we report an improved magnesium hydroxide, Mg(OH)2, coprecipitation method for the determination of 16 trace elements (Al, V, Cr, Mn, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sb, Sn and Pb) and 18 rare earth elements (REEs), including Sc, Y, U and Th in seawater and estuarine water samples. The procedure involves coprecipitation of the trace elements and REEs on Mg(OH)2 upon addition of a small volume of triethylamine (TEA) followed by analysis of the dissolved pellet solutions by inductively coupled plasma mass spectrometry (ICP-MS). Three-step sequential coprecipitation was carried out on 10 mL aliquots of seawater to eliminate the matrix ions and to preconcentrate the analytes of interest into a 1 mL final volume. Spike recoveries varied from 85% (Th) to 105% (Y). Calcium (Ca), sodium (Na) and potassium (K) matrices were virtually eliminated from the analysis solutions. Collision reaction interface (CRI) technology utilizing H2 and He gases was employed to determine its effectiveness in removing the spectral interferences originating from the residual Mg matrix, TEA and plasma gases. H2 was more effective than He in reducing spectral interferences from TEA and plasma gases. Limits of detection (LODs) ranged from 0.01 ng L−1 (Ho) to 72 ng L−1 (Al). The method was validated by using certified seawater (CASS-4) and estuarine water (SLEW-3) reference materials. Precision for five (n = 5) replicate measurements were between 1.2% (Pr) and 18% (Lu). Fe, Pb, Sn, and Zn impurities in TEA were significant in comparison to the levels in CASS-4 and SLEW-3, while relatively high background signals impacted determinations of low levels of Sc and Th. The effects of these hurdles on precision and accuracy were alleviated by measuring these elements in spiked CASS-4 and SLEW-3.
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2018.01.017
      Issue No: Vol. 1008 (2018)
       
  • Voltammetric determination of tartaric acid in wines by electrocatalytic
           oxidation on a cobalt(II)-phthalocyanine-modified electrode associated
           with multiway calibration
    • Authors: Anabel S. Lourenço; Raphael F. Nascimento; Amanda C. Silva; Williame F. Ribeiro; Mario C.U. Araujo; Severino C.B. Oliveira; Valberes B. Nascimento
      Pages: 29 - 37
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Anabel S. Lourenço, Raphael F. Nascimento, Amanda C. Silva, Williame F. Ribeiro, Mario C.U. Araujo, Severino C.B. Oliveira, Valberes B. Nascimento
      The electrocatalytic oxidation of tartaric acid on a carbon paste electrode modified with cobalt (II)-phthalocyanine was demonstrated and applied to the development of a highly sensitive, simple, fast and inexpensive voltammetric sensor to determine tartaric acid. The electrochemical behavior of the modified electrode was investigated by cyclic and square wave voltammetry, and the effect of experimental variables, such as dispersion and loading of cobalt (II)-phthalocyanine, together with optimum conditions for sensing the analyte by square wave voltammetry were assessed. In addition, the absence of a significant memory effect combined with the ease of electrode preparation led to the development of a sensitive and direct method to determine tartaric acid in wines. Interferences from other low molecular weight organic acids commonly present in wines were circumvented by using a multiway calibration technique, successfully obtaining the second order advantage by modeling voltammetric data with unfolded partial least square with residual bilinearization (U-PLS/RBL). A linear response range between 10 and 100 μmol L−1 (r = 0.9991), a relative prediction error of 4.55% and a recovery range from 96.41 to 102.43% were obtained. The proposed method is non-laborious, since it does not use sample pretreatment such as filtration, extraction, pre-concentration or cleanup procedures.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2018.01.005
      Issue No: Vol. 1008 (2018)
       
  • Synthesis of gold-palladium nanowaxberries/dodecylamine-functionalized
           graphene quantum dots-graphene micro-aerogel for voltammetric
           determination of peanut allergen Ara h 1
    • Authors: Ruiyi Li; Ling Liu; Haiyan Zhu; Zaijun Li
      Pages: 38 - 47
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Ruiyi Li, Ling Liu, Haiyan Zhu, Zaijun Li
      The paper reports synthesis of gold-palladium nanowaxberries(AuPd NWs)/dodecylamine-functionalized graphene quantum dots(D-GQDs)-graphene micro-aerogel(GMA). D-GQDs was used as a solid particle surfactant for stabilizing Pickering emulsion of toluene-in-graphene oxide aqueous dispersion. Graphene oxide sheets in the aqueous phase are reduced by hydrazine hydrate, diffused into the toluene droplet and self-assembled into graphene oxide micro-gels. Followed by freeze-drying, thermal annealing and hybridized with AuPd NWs. The as-prepared AuPd NWs/D-GQDs-GMA shows an unique three-dimensional structure with the size of microns. The small size and strong polarity make it can be directly dispersed in ethanol to form stable dispersion for sensor preparation. The hybrid of GMA, D-GQDs and AuPd NWs greatly improves the electron transfer, electroactive surface area and ion diffusion. The architecture of conductor/semiconductor/conductor achieves to a significant amplification of detection signal. The DNA biosensor based on the AuPd NWs/D-GQDs-GMA exhibits ultrasensitive differential pulse voltammetric (DPV) response towards peanut allergen Ara h 1. The DPV signal linearly increases with increasing DNA concentration in the range of 1.0 × 10−22-1.0 × 10−17 M with the detection limit of 4.7 × 10−23 M (S/N = 3). The analytical method was successfully applied to voltammetric determination of peanut allergen Ara h 1 in peanut milk beverage.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2018.01.031
      Issue No: Vol. 1008 (2018)
       
  • A novel aptamer-based online magnetic solid phase extraction method for
           the selective determination of 8-hydroxy-2′-deoxyguanosine in human
           urine
    • Authors: Haijiao Gan; Hui Xu
      Pages: 48 - 56
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Haijiao Gan, Hui Xu
      In this work, an innovative magnetic aptamer adsorbent (Fe3O4-aptamer MNPs) was synthesized for the selective extraction of 8-hydroxy-2′-deoxyguanosine (8-OHdG). Amino-functionalized-Fe3O4 was crosslinked with 8-OHdG aptamer by glutaraldehyde and fixed into a steel stainless tube as the sorbent of magnetic solid phase extraction (MSPE). After selective extraction by the aptamer adsorbent, the adsorbed 8-OHdG was desorbed dynamically and online analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS). The synthesized sorbent presented outstanding features, including specific selectivity, high enrichment capacity, stability and biocompatibility. Moreover, this proposed MSPE-HPLC-MS can achieve adsorption and desorption operation integration, greatly simplify the analysis process and reduce human errors. When compared with offline MSPE, a sensitivity enhancement of 800 times was obtained for the online method. Some experimental parameters such as the amount of the sorbent, sample flow rate and sample volume, were optimized systematically. Under the optimal conditions, low limit of detection (0.01 ng mL−1, S/N = 3), limit of quantity (0.03 ng mL−1, S/N = 10) and wide linear range with a satisfactory correlation coefficient (R2 ≥ 0.9992) were obtained. And the recoveries of 8-OHdG in the urine samples varied from 82% to 116%. All these results revealed that the method is simple, rapid, selective, sensitive and automated, and it could be expected to become a potential approach for the selective determination of trace 8-OHdG in complex urinary samples.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.032
      Issue No: Vol. 1008 (2018)
       
  • Highly selective determination of ultratrace inorganic arsenic species
           using novel functionalized miniaturized membranes
    • Authors: Ewa Lukojko; Ewa Talik; Anna Gagor; Rafal Sitko
      Pages: 57 - 65
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Ewa Lukojko, Ewa Talik, Anna Gagor, Rafal Sitko
      A simple method for highly selective determination of trace and ultratrace arsenic ions, i.e. arsenite and arsenate, was developed. The method is based on new miniaturized membranes, 5 mm diameter and 4.4 mg weight, which are prepared by synthesis of amorphous silica coating on cellulose fibers followed by the modification with (3-mercaptopropyl)-trimethoxysilane. The batch adsorption experiments show that membranes have high selectivity toward arsenite in the presence of heavy metals and anions that usually exist in natural water. Arsenite can be quantitatively adsorbed at pH 1 from 50 mL sample within 60 min using the miniaturized membrane with maximum adsorption capacity of 60 mg g−1. The excellent adsorptive properties of membranes open the path to simple and selective determination of trace and ultratrace arsenite in water. Moreover, the membranes can be applied in the arsenic speciation due to their selectivity toward arsenite in the presence of arsenate. After adsorption, the arsenite retained onto the membrane is directly measured by energy-dispersive X-ray fluorescence spectrometry, avoiding elution step usually required in other spectroscopy techniques. The method is characterized by excellent enrichment factor of 972, detection limit of 0.045 ng mL−1 and can be successfully applied in analysis of high salinity water, which is difficult to analyze by other spectroscopy techniques. The proposed method is a solvent-free approach based on the use of miniaturized membranes as sorbent followed by the direct measurement using a low-power X-ray spectrometer without either elution step or gas consumption during measurement. It can be considered as environmentally friendly and meets the standards of green analytical chemistry principles.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.038
      Issue No: Vol. 1008 (2018)
       
  • Improved approach for routine monitoring of 129I activity and 129I/127I
           atom ratio in environmental samples using TMAH extraction and ICP-MS/MS
    • Authors: Guosheng Yang; Hirofumi Tazoe; Masatoshi Yamada
      Pages: 66 - 73
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Guosheng Yang, Hirofumi Tazoe, Masatoshi Yamada
      To reconstruct 131I deposition and identify the source of radioiodine due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, 129I activity and 129I/127I atom ratio should be obtained by preparing and analyzing large numbers of samples economically. In this study, great efforts were made to realize mild TMAH (tetramethyl ammonium hydroxide) extraction of environmental samples at 90 °C to obtain solutions suitable for the following triple-quadrupole inductively coupled plasma-mass spectrometry (ICP-QQQ) MS/MS mode analysis. After releasing iodine from organic matter in the TMAH extraction solution via K2S2O8 oxidation, organic matter was removed effectively by solvent extraction and back-extraction to avoid a serious matrix effect during ICP-QQQ analysis. At the same time, interfering elements, especially, Mo, Cd, and In were also removed effectively, to avoid their undesirable interferences during mass spectrometric analysis. In addition, 0.01% (NH4)2SO3 was selected to introduce I− into ICP-QQQ to ensure there was no memory effect and a stable signal was gotten. Subsequently, ICP-QQQ MS/MS mode was applied to further eliminate polyatomic interferences (127I(H2 and D)+, 97MoO2 +, 113InO+, and 113CdO+) and isobaric interference from 129Xe+. Finally, the developed method was successfully applied to measure 129I/127I atom ratios ((2.61–27.0) × 10−7) and 129I activities (3.51–11.4 mBq kg−1) in soil samples. The developed method allows a greater number of ordinary laboratories to participate in the field of radioiodine analysis.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.049
      Issue No: Vol. 1008 (2018)
       
  • High-pressure photon ionization time-of-flight mass spectrometry combined
           with dynamic purge-injection for rapid analysis of volatile metabolites in
           urine
    • Authors: Yan Wang; Lei Hua; Jichun Jiang; Yuanyuan Xie; Keyong Hou; Qingyun Li; Chenxin Wu; Haiyang Li
      Pages: 74 - 81
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Yan Wang, Lei Hua, Jichun Jiang, Yuanyuan Xie, Keyong Hou, Qingyun Li, Chenxin Wu, Haiyang Li
      Small molecule metabolites are widely used as biomarkers in the research field of metabolomics for disease diagnosis and exposure assessment. As a readily available biofluid containing plenty of volatile organic metabolites (VOMs), urine is ideal for non-invasive metabolomic analysis; however, there is still lack of rapid analysis method for VOMs in urine. Here we report a kind of rapid method for urine analysis by employing high-pressure photon ionization time-of-flight mass spectrometry (HPPI-TOFMS) combined with dynamic purge-injection. Various types of metabolites, such as ketones, alcohols, acids, sulfides, pyrroles and amines were detected directly by simple acidification or alkalization of urines. It is noteworthy that nitrogen-containing compounds, especially polar amines, could be ultrasensitively measured without any derivatization. The analytical capability of the direct HPPI-MS technique was demonstrated by analyzing five valuable metabolites, i.e., toluene, 2,5-dimethylpyrrole, trimethlyamine, styrene, and p-xylene, which exhibited relatively low limits of detection, wide linear range and satisfactory repeatability. Being highly sensitive and humidity-friendly, the whole analytical procedure is easily operated in less than 6 min. Interestingly, a new biomarker 2,5-dimethylpyrrole was exclusively found in the smoker's urine sample besides toluene. The work presents a novel tool for rapid nontarget disease biomarkers screening or target monitoring of specific compounds through the investigation of volatile metabolites in urine.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2018.01.006
      Issue No: Vol. 1008 (2018)
       
  • Double labelling of intracellular mitochondria and nucleolus using
           thiophene pyridium salt with high quantum yield as biosensor and its
           application in stimulated emission depletion nanoscopy
    • Authors: Xiaohe Tian; Hui Wang; Qiong Zhang; Mingzhu Zhang; Yingzhong Zhu; Yan Chen; Jieying Wu; Yupeng Tian
      Pages: 82 - 89
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Xiaohe Tian, Hui Wang, Qiong Zhang, Mingzhu Zhang, Yingzhong Zhu, Yan Chen, Jieying Wu, Yupeng Tian
      Probe for dual-site target distinct subcellular compartments from cytosol and nucleus is an attractive approach, however, which was scarcely reported. Herein, a series of small-molecular thiophene pyridium salt derivatives (MitoNuc1-4) possessing water-soluble, high quantum yield and two-photon activity were rationally designed, and their structures were crystallographic confirmed. Systematic photophysical and biological imaging property investigations were carried out for them. It was found that MitoNuc1-4 exhibit two-photon absorption properties in the near infrared region, and MitoNuc1 has membrane permeability and cationic nature, rendering it to be double labelling of mitochondria and nucleolus in living cells with superb photo-stability and non-invasiveness. It also demonstrated that MitoNuc1 in living cells can monitor mitochondrial division in real time and revealed nucleolar ultrastructure under stimulated emission depletion nanoscopy.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.033
      Issue No: Vol. 1008 (2018)
       
  • Nickel-mediated allosteric manipulation of G-quadruplex DNAzyme for highly
           selective detection of histidine
    • Authors: Zijun Li; Jian Zhao; Zhaoyin Wang; Zhihui Dai
      Pages: 90 - 95
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Zijun Li, Jian Zhao, Zhaoyin Wang, Zhihui Dai
      Since abnormal metabolism of histidine (His) is defined as an indicator of several diseases, detection of His in biological fluids becomes increasingly urgent to us. However, due to similar structures and properties of different amino acids, selective quantification of His is difficulty, and typically needs the participation of special reagents. In this work, we report for the first time that nickel ions (Ni2+) can induce the allostery of G-quadruplex, and is thus able to manipulate the activity of G-quadruplex DNAzyme. Experimental results indicate the interaction between Ni2+ and guanine is critical to the allostery. In comparison with Ni2+-guanine interaction, Ni2+-His interaction exhibits higher affinity. Therefore, a colorimetric His biosensor is fabricated, and His can be facilely discriminated by naked eyes. Relying on the high activity of DNAzyme, His in a range of 50 nM–400 μM is determined with this method, and low detection limit (36 nM) is obtained. More importantly, His can be directly distinguished in the absence of other toxic reagents. In addition, the amount of His in serum is also measured, suggesting the applicability of this biosensor in real sample detection. Overall, this work provides an alternative way to design G-quadruplex DNAzyme-based analytical approaches.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.040
      Issue No: Vol. 1008 (2018)
       
  • Amplified fluorescence detection of serum prostate specific antigen based
           on metal-dependent DNAzyme assistant nanomachine
    • Authors: Binxiao Li; Jing Liu; Hong Zhou
      Pages: 96 - 102
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Binxiao Li, Jing Liu, Hong Zhou
      An amplified fluorescence biosensing strategy for serum prostate specific antigen (PSA) was developed on the basis of DNAzyme. In presence of cofactor Zn2+, Zn2+ -dependent DNAzyme could cleave the hairpin substrate probes which were dispersed in solution and generate remarkable fluorescent signal. Taking advantage of the magnetic beads as a carrier, one target protein could bring plentiful hairpin substrate probes on to the electrode through a sandwich structure (Ab1/PSA/biotin-Ab2). Moreover, during the cleavage process of as formed DNAzyme, DNAzyme did not be destroyed and could further react with other hairpin probes, then generated continuous fluorescent signal. Benefited by this amplified strategy, the limit of detection (LOD) was low to 0.05 ng mL−1, which was much lower than our previous reports. This method could be applied to detect different protein biomarkers in serum without corresponding aptamers by changing the corresponding antibodies and thus showed a remarkable prospect in clinical application.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.041
      Issue No: Vol. 1008 (2018)
       
  • “Turn-off” fluorescent sensor based on double quantum dots coupled
           with chemometrics for highly sensitive and specific recognition of 53
           famous green teas
    • Authors: Ou Hu; Lu Xu; Haiyan Fu; Tianming Yang; Yao Fan; Wei Lan; Hebing Tang; Yu Wu; Lixia Ma; Di Wu; Yuan Wang; Zuobing Xiao; Yuanbin She
      Pages: 103 - 110
      Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008
      Author(s): Ou Hu, Lu Xu, Haiyan Fu, Tianming Yang, Yao Fan, Wei Lan, Hebing Tang, Yu Wu, Lixia Ma, Di Wu, Yuan Wang, Zuobing Xiao, Yuanbin She
      Fluorescent “turn-off” sensors based on double quantum dots (QDs) has attracted increasing attention in the detection of many materials due to their properties such as more useful information, higher fluorescence efficiency and stability compared with the fluorescent “turn-off” sensors based on single QDs. In this work, highly sensitive and specific method for recognition of 53 different famous green teas was developed based on the fluorescent “turn-off” model with water-soluble ZnCdSe-CdTe double QDs. The fluorescence of the two QDs can be quenched by different teas with varying degrees, which results in the differences in positions and intensities of two peaks. By the combination of classic partial least square discriminant analysis (PLSDA), all the green teas can be discriminated with high sensitivity, specificity and a satisfactory recognition rate of 100% for training set and 100% for prediction set, respectively. The fluorescent “turn-off” sensors based on the single QDs (either ZnCdSe QDs or CdTe QDs) coupled with PLSDA were also employed to recognize the 53 famous green teas with unsatisfactory results. Therefore, the fluorescent “turn-off” sensors based on the double QDs is more appropriate for the large-class-number classification (LCNC) of green teas. Herein, we have demonstrated, for the first time, that so many kinds of famous green teas can be discriminated by the “turn-off” model of double QDs combined with chemometrics, which has largely extended the capability of traditional fluorescence and chemometrics, as well as exhibits great potential to perform LCNC in other practical applications.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.042
      Issue No: Vol. 1008 (2018)
       
  • Simultaneous detections of genetic fragment and single nucleotide mutation
           with a three-tiered output for tuberculosis diagnosis
    • Authors: Shih-Ying Huang; Jia-Ru Chang; Yu-Chieh Liao; Horng-Yunn Dou; Min-Chieh Chuang
      Pages: 1 - 9
      Abstract: Publication date: 12 May 2018
      Source:Analytica Chimica Acta, Volume 1007
      Author(s): Shih-Ying Huang, Jia-Ru Chang, Yu-Chieh Liao, Horng-Yunn Dou, Min-Chieh Chuang
      Tuberculosis (TB) remains one of the major infectious diseases worldwide. The pathogenic bacterium, Mycobacterium tuberculosis (M.tb), continuously evolves strains carrying drug-resistance genes, thus posing a growing challenge to TB prevention and treatment. We report a diagnostic system that uses a molecular beacon probe and an assistant strand as the core to simultaneously interact with an M.tb-specific fragment (in IS6110) and a single nucleotide substitution (SNS)-encoded segment (in rpoB) associated with drug resistance. A single fluorescent output in three-tiered levels was produced for combinatorial interpretations based on formation of a four-way DNA junction (4WJ). The SNS caused the 4WJ to partially dissociate, thus resulting in medium-level fluorescence. By contrast, high- and low-level fluorescence, represented the complete complementary complex and absence of either targeted fragments, respectively. Manipulating the length of the analyte-binding arm realized the medium output. The thermodynamics and kinetics of 4WJ construction were investigated to maximize the tiered-output performance. Biocatalytic amplification driven by the Klenow Fragment and Nt.AlwI was incorporated into the method to enhance the signal 64-fold and ensure long-term stability of the three-tiered output. The detection accuracy of the sensing system was verified using unpurified amplicons with templates of extracted DNA and boiled bacterial solutions. The tiered-output mechanism was usable at bacterial loads ranging from 4 × 100 to 4 × 103 CFU per reaction. The interference caused by nontuberculous mycobacteria was minimal. The results demonstrated the integrity of the sensing method as an alternative strategy for rapid screening of M.tb and detecting rifampin-resistance.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.028
      Issue No: Vol. 1007 (2018)
       
  • Additive Partial Least Squares for efficient modelling of independent
           variance sources demonstrated on practical case studies
    • Authors: Pekka Luoma; Thomas Natschläger; Birgit Malli; Marcin Pawliczek; Markus Brandstetter
      Pages: 10 - 15
      Abstract: Publication date: 12 May 2018
      Source:Analytica Chimica Acta, Volume 1007
      Author(s): Pekka Luoma, Thomas Natschläger, Birgit Malli, Marcin Pawliczek, Markus Brandstetter
      A model recalibration method based on additive Partial Least Squares (PLS) regression is generalized for multi-adjustment scenarios of independent variance sources (referred to as additive PLS - aPLS). aPLS allows for effortless model readjustment under changing measurement conditions and the combination of independent variance sources with the initial model by means of additive modelling. We demonstrate these distinguishing features on two NIR spectroscopic case-studies. In case study 1 aPLS was used as a readjustment method for an emerging offset. The achieved RMS error of prediction (1.91 a.u.) was of similar level as before the offset occurred (2.11 a.u.). In case-study 2 a calibration combining different variance sources was conducted. The achieved performance was of sufficient level with an absolute error being better than 0.8% of the mean concentration, therefore being able to compensate negative effects of two independent variance sources. The presented results show the applicability of the aPLS approach. The main advantages of the method are that the original model stays unadjusted and that the modelling is conducted on concrete changes in the spectra thus supporting efficient (in most cases straightforward) modelling. Additionally, the method is put into context of existing machine learning algorithms.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.027
      Issue No: Vol. 1007 (2018)
       
  • A high resolution atmospheric pressure matrix-assisted laser
           desorption/ionization-quadrupole-orbitrap MS platform enables in situ
           analysis of biomolecules by multi-mode ionization and acquisition
    • Authors: Bingming Chen; Chuanzi OuYang; Zichuan Tian; Meng Xu; Lingjun Li
      Pages: 16 - 25
      Abstract: Publication date: 12 May 2018
      Source:Analytica Chimica Acta, Volume 1007
      Author(s): Bingming Chen, Chuanzi OuYang, Zichuan Tian, Meng Xu, Lingjun Li
      Introduced in 2000, atmospheric pressure (AP)/matrix-assisted laser desorption/ionization (MALDI) has attracted substantial attention in the mass spectrometry community due to its ease of sample introduction and handling, interchangeability with ESI source and capability of analyzing volatile species. In this study, an AP/MALDI source with ultra-high spatial resolution was coupled to a Q Exactive HF orbitrap mass spectrometer for high resolution in situ analysis by MALDI, laserspray ionization (LSI) and matrix assisted ionization (MAI) without instrument modification. LSI and MAI generated multiply charged ions, which expanded the mass detection range and improved fragmentation efficiency. Full MS, targeted MS/MS, data dependent acquisition (DDA) and parallel reaction monitoring (PRM) acquisitions were performed on peptide and protein standards, tissue extracts and tissue sections for in depth characterization of various biomolecules. High resolution full MS and MS/MS images were obtained from crustacean and rat tissues with pixel size less than 30 μm. Overall, AP/MALDI-Q-Orbitrap is a fast scanning instrument that is capable of performing multiple types of ionization and multiple acquisition modes without instrument modification. This instrument platform provides an attractive alternative to other high resolution MALDI instruments.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.045
      Issue No: Vol. 1007 (2018)
       
  • Single cell patterning for high throughput sub-cellular toxicity assay
    • Authors: Junfei Xia; Yuting Qiu; Xiaojie Xun; Liyuan Ma; Jingjiao Guan; Ming Su
      Pages: 26 - 32
      Abstract: Publication date: 12 May 2018
      Source:Analytica Chimica Acta, Volume 1007
      Author(s): Junfei Xia, Yuting Qiu, Xiaojie Xun, Liyuan Ma, Jingjiao Guan, Ming Su
      Cell population based toxicity assays cannot distinguish responses of single cells and sub-cellular organelles; while single cell assays are limited by low statistical power due to small number of cells examined. This article reports a new single cell array based toxicity assay, in which cell responses at population level, single cell level and sub-cellular level can be obtained simultaneously at high throughput. The single cell array was produced by microcontact printing and selected area cell attachment, and exposed to damaging X-ray radiation, which was followed by fluorescence imaging after staining. Two image processing softwares written in Python and MATLAB were used to determine the expressions of proteins associated with cell migration and invasion, and production of reactive oxygen species (ROS), respectively. The results showed significant differences in responses at single cell level and distinctive molecular heterogeneity at sub-cellular level in a large population of cells upon exposure to radiation.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.11.044
      Issue No: Vol. 1007 (2018)
       
  • Citrate-capped silver nanoparticles as a probe for sensitive and selective
           colorimetric and spectrophotometric sensing of creatinine in human urine
    • Authors: Melisew Tadele Alula; Leshern Karamchand; Nicolette R. Hendricks; Jonathan M. Blackburn
      Pages: 40 - 49
      Abstract: Publication date: 12 May 2018
      Source:Analytica Chimica Acta, Volume 1007
      Author(s): Melisew Tadele Alula, Leshern Karamchand, Nicolette R. Hendricks, Jonathan M. Blackburn
      Urinary creatinine concentration is a critical physiological parameter that enables reliable assessment of patient renal function and diagnosis of a broad spectrum of diseases. In this study, a simple and inexpensive sensor comprising monodisperse, citrate-capped silver nanoparticles (cc-AgNPs) was developed, which enabled rapid, sensitive and selective quantitation of creatinine directly in unprocessed urine. The mechanism of this sensor entails the creatinine-mediated aggregation of the cc-AgNPs (within 1 min) under alkaline conditions (pH 12). This is attributed to the tautomerization of creatinine to its amino anionic species at alkaline pH, which cross-link the cc-AgNPs via hydrogen bond networks with the negatively charged citrate caps. Creatinine elicited visibly-discernable color changes of the cc-AgNPs colloids in a concentration-dependent manner up to 10 μM. UV-visible spectroscopic analyses of the cc-AgNPs revealed that creatinine elicited a concentration-dependent decrease in intensity of the localized surface plasmon resonance (LSPR) band centered around 403 nm, with a concomitant increase in intensity of the red-shifted LSPR band at 670 nm. This observation denotes a creatinine-mediated increase in cc-AgNP particle size via aggregation, as confirmed by transmission electron microscopy analysis. The cc-AgNP sensor exhibited a linear correlation between the A670/A403 extinction ratio and creatinine concentration range of 0–4.2 μM in aqueous solutions (R 2 = 0.996), and a low detection limit of 53.4 nM. Hence, the simplicity, short assay time, and high sensitivity and selectivity of our cc-AgNP sensor affirms its utility as a creatinine monitoring assay for low-resource, point-of-care settings.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.016
      Issue No: Vol. 1007 (2018)
       
  • Double-enhanced lateral flow immunoassay for potato virus X based on a
           combination of magnetic and gold nanoparticles
    • Authors: Shyatesa C. Razo; Vasily G. Panferov; Irina V. Safenkova; Yuri A. Varitsev; Anatoly V. Zherdev; Boris B. Dzantiev
      Pages: 50 - 60
      Abstract: Publication date: 12 May 2018
      Source:Analytica Chimica Acta, Volume 1007
      Author(s): Shyatesa C. Razo, Vasily G. Panferov, Irina V. Safenkova, Yuri A. Varitsev, Anatoly V. Zherdev, Boris B. Dzantiev
      This study presents the joint use of magnetic nanoparticles (MNPs) and gold nanoparticles (GNPs) for double enhancement in a lateral flow immunoassay (LFIA). The study realizes two types of enhancement: (1) increasing the concentration of analytes in the samples using conjugates of MNPs with specific antibodies and (2) increasing the visibility of the label through MNP aggregation caused by GNPs. The proposed strategy was implemented using a LFIA for potato virus X (PVX), a significant potato pathogen. MNPs conjugated with biotinylated antibodies specific to PVX and GNPs conjugated with streptavidin were synthesized and characterized. The LFIAs with and without the proposed enhancements were compared. The double-enhanced LFIA achieved the highest sensitivity, equal to 0.25 ng mL−1 and 32 times more sensitivity than the non-enhanced LFIA (detection limit: 8 ng mL−1). LFIAs using one of the types of amplification (magnetic concentration without GNPs-causing aggregation or MNP aggregation without the concentration stage) showed intermediate levels of sensitivity. The double-enhanced LFIA was successfully used for PVX detection in potato leaves. The results for PVX detection in the infected plants were similar for the double-enhanced LFIA developed and the conventional LFIA based on the GNP conjugates; however, the new system provided significant coloring enhancement. This study confirmed that a simple combination of MNPs and GNPs has great potential for high-sensitivity detection and could possibly be adopted for LFIAs of other compounds.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.023
      Issue No: Vol. 1007 (2018)
       
  • The label-free immunosensor based on rhodium@palladium nanodendrites/sulfo
           group functionalized multi-walled carbon nanotubes for the sensitive
           analysis of carcino embryonic antigen
    • Authors: Hui Lv; Yueyun Li; Xiaobo Zhang; Zengqiang Gao; Jinhui Feng; Ping Wang; Yunhui Dong
      Pages: 61 - 70
      Abstract: Publication date: 12 May 2018
      Source:Analytica Chimica Acta, Volume 1007
      Author(s): Hui Lv, Yueyun Li, Xiaobo Zhang, Zengqiang Gao, Jinhui Feng, Ping Wang, Yunhui Dong
      In this work, bimetallic core-shell rhodium@palladium nanodendrites (Rh@Pd NDs) loaded on sulfo group functionalized multi-walled carbon nanotubes (MWCNTs-SO3H) were combined to form Rh@Pd NDs/MWCNTs-SO3H nanocomposites. And the composites were used to construct a simple and label-free electrochemical immunosensor for carcino embryonic antigen (CEA) detection using differential pulse voltammetry (DPV). Rh@Pd NDs with dendritic nanostructure not only provide abundant catalytically active sites, but also increase the loading of antibody, which could improve the analytical performance and result in high sensitivity. In addition, the MWCNTs-SO3H could further enhance electrochemical properties due to the excellent conductivity, good solubility and high surface area. Taking advantages of both Rh@Pd NDs and MWCNTs-SO3H, the proposed immunosensor showed a broad linear range from 25 fg mL−1 to 100 ng mL−1 for CEA detection and a low detection limit of 8.3 fg mL−1 (signal-to-noise ratio of 3) under optimal experimental conditions. Moreover, the expected immunosensor exhibited good reproducibility and high sensitivity, which could achieve excellent analysis of CEA in human serum with satisfactory results. Therefore, the Rh@Pd NDs/MWCNTs-SO3H nanocomposites may be considered as a sensing platform for fabrication of simple, ultrasensitive and label-free electrochemical immunosensor.
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.030
      Issue No: Vol. 1007 (2018)
       
  • Simultaneous determination of 11 phthalate esters in bottled beverages by
           graphene oxide coated hollow fiber membrane extraction coupled with
           supercritical fluid chromatography
    • Authors: Chaoyan Lou; Dandan Guo; Kai Zhang; Can Wu; Peimin Zhang; Yan Zhu
      Pages: 71 - 79
      Abstract: Publication date: 12 May 2018
      Source:Analytica Chimica Acta, Volume 1007
      Author(s): Chaoyan Lou, Dandan Guo, Kai Zhang, Can Wu, Peimin Zhang, Yan Zhu
      Phthalate esters (PAEs) are a group of serious environmental pollutants, which lead to carcinogenicity or tumorigenicity in human body. In this study, a rapid, sensitive and green method by graphene oxide coated hollow fiber membrane extraction (GO-HFME) coupled with supercritical fluid chromatography (SFC) was proposed for the determination of 11 phthalate esters in bottled beverages. Graphene oxide (GO) was prepared and coated onto a porous hollow fiber membrane (HFM) to reinforce the efficiency of membrane extraction. The modified hollow fiber membrane was employed for the extraction of phthalate esters from bottled beverages prior to the determination by the supercritical fluid chromatography with UV detection. To achieve the maximum extraction efficiency, several parameters were investigated including GO concentration, extraction time, desorption solution and desorption time. SFC variables including stationary phase, modifier composition and percentage, column temperature, flow rate and backpressure were studied to improve the separation conditions. Under these optimized conditions, all the studied 11 phthalate esters were well separated and simultaneously determined in 7 min by SFC. The performance of the developed method was evaluated. Good linearity was observed (R ≥ 0.999) in the range of 0.02–10.0 μg/mL with limit of detection (LOD, S/N = 3) ranging from 1.5 to 3.0 ng/mL. Recoveries of all the PAEs for the spiked samples were between 92.1% and 99.3% with satisfactory relative standard deviations (RSD) less than 5.9%. The proposed method is time-saving, green, simple and robust, which will be an alternative way to the analysis of PAEs in real samples.
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.018
      Issue No: Vol. 1007 (2018)
       
  • Optical and surface plasmonic approaches to characterize extracellular
           vesicles. A review
    • Authors: Victoria Shpacovitch; Roland Hergenröder
      Pages: 1 - 15
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): Victoria Shpacovitch, Roland Hergenröder
      Extracellular vesicles (EVs) have been recognized as messengers delivering various active molecules between cells. This feature of EVs drew the attention of clinicians as well as researchers from different fields. However, exciting ideas to employ EVs as means of drug delivery or to test them as biomarkers of cellular status require very thoughtful and attentive approaches to the selection of analytical techniques for EV characterization. Optical and surface plasmonic analytical methods offer a researcher an invaluable opportunity to use already sized and/or quantified EVs in further functional cell-based assays and in focused biochemical tests (nucleic acid and protein arrays, etc.). Moreover, a high sensitivity and relative flexibility of surface plasmonic sensors open a possibility to develop instruments performing quantitative, metrical and EV surface/content analysis in a single device. This review aims to consider the applicability of established and modern optical techniques as well as novel surface plasmonic approaches for different aspects of EV analysis.
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.11.066
      Issue No: Vol. 1005 (2018)
       
  • Diethyldithiocarbamate enhanced chemical generation of volatile palladium
           species, their characterization by AAS, ICP-MS, TEM and DART-MS and
           proposed mechanism of action
    • Authors: Jaromír Vyhnanovský; Jan Kratzer; Oldřich Benada; Tomáš Matoušek; Zoltán Mester; Ralph E. Sturgeon; Jiří Dědina; Stanislav Musil
      Pages: 16 - 26
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): Jaromír Vyhnanovský, Jan Kratzer, Oldřich Benada, Tomáš Matoušek, Zoltán Mester, Ralph E. Sturgeon, Jiří Dědina, Stanislav Musil
      Comprehensive investigation of chemical generation of volatile species (VSG) of palladium for detection by analytical atomic and mass spectrometry and, specifically, the mechanistic aspects of their formation and tentative identification are presented. VSG was achieved in a flow injection mode using a generator that permitted rapid mixing of acidified sample with NaBH4 reductant. Atomization in a diffusion flame with detection by atomic absorption spectrometry was exclusively used for optimization of generation conditions while inductively coupled plasma mass spectrometry was utilized to investigate overall system efficiency and analytical metrics of the VSG system for potential ultratrace analysis. Sodium diethyldithiocarbamate (DDTC) served as a crucial reaction modifier, enhancing overall system efficiency 9-fold. Combinations of modifiers, Triton X-100 and Antifoam B surfactants provided a synergistic effect to yield a further 2-fold enhancement of VSG. The overall system efficiency was in the range 16–22%, with higher efficiencies correlating with higher Pd concentrations. The contribution of co-generated aerosol to the overall system efficiency, determined by means of concurrent measurement of added Cs, was negligible – less than 0.1%. The nature of the volatile species was investigated using several approaches, but principally by transmission electron microscopy (TEM) after their collection on a grid, and by direct analysis in real time (DART) using high resolution orbitrap mass spectrometry. These experiments suggest a parallel but dual-route mechanism of VSG of Pd, one attributed to generation of a volatile DDTC chelate of Pd and a second to nanoparticle formation.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.013
      Issue No: Vol. 1005 (2018)
       
  • Regulating immobilization performance of metal-organic coordination
           polymers through pre-coordination for biosensing
    • Authors: Hua Yang; Xin Qi; Xinquan Wang; Xiangyun Wang; Qiang Wang; Peipei Qi; Zhiwei Wang; Xiahong Xu; Yingchun Fu; Shouzhuo Yao
      Pages: 27 - 33
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): Hua Yang, Xin Qi, Xinquan Wang, Xiangyun Wang, Qiang Wang, Peipei Qi, Zhiwei Wang, Xiahong Xu, Yingchun Fu, Shouzhuo Yao
      We propose a method for regulating biomolecules immobilization performance of metal-organic coordination polymers (MOCPs) through pre-coordination for highly sensitive biosensing. 2,5-dimercapto-1,3,4-thiadiazole (DMcT) was used as organic monomers. Firstly, using CuCl2 as the source of metal ions to form short oligomers with DMcT (MOCPsCu), which can regulate the length of ligands through pre-coordination. Then exploiting NaAuCl4 as the source of Au ions to coordinate both short oligomers and biomolecules (MOCPsCu+Au), since Au ions can coordinate with both N and S atoms. Through controlling the concentration of CuCl2, oligomers with desired length could be readily obtained to prepare MOCPsCu+Au framework with controllable porosity and enzyme entrapment efficiency. Thus MOCPsCu+Au offers several advantages including improved mass transfer efficiency and biocatalytic sensitivity than conventional MOCPs using single metal ions. Glucose oxidase (GOx) was used as the representative biomolecule, the entrapment ratio of enzyme in MOCPsCu+Au case reached an extreme value of 100%. These MOCPsCu+Au biocomposites modified electrode also showed greatly enhanced biocatalytic sensitivity (127 μA cm−2 mM−1) and very low detection limit (58 nM), compared with those reported analogues. The new materials/strategy may create new avenue to regulate the performance of ligand-constructed polymers and their composites for entrapment-based applications.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.11.011
      Issue No: Vol. 1005 (2018)
       
  • Semi-automated set-up for exhaustive micro-electromembrane extractions of
           basic drugs from biological fluids
    • Authors: Miloš Dvořák; Knut Fredrik Seip; Stig Pedersen-Bjergaard; Pavel Kubáň
      Pages: 34 - 42
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): Miloš Dvořák, Knut Fredrik Seip, Stig Pedersen-Bjergaard, Pavel Kubáň
      Manual handling of microliter volumes of samples and reagents is usually prone to errors and may have direct consequence on the overall performance of microextraction process. Direct connection of a syringe pump and a disposable microextraction unit using flexible polymeric tubing was employed for semi-automated liquid handling in micro-electromembrane extraction (μ-EME). A three-phase μ-EME system was formed by consecutive withdrawal of microliter volumes of donor solution, free liquid membrane (FLM) and acceptor solution into the unit. Excellent repeatability and accuracy of the withdrawal sequence was achieved for solution volumes typically used in μ-EME (1–5 μL) as well as excellent correlation between the initially withdrawn and the finally collected solution volumes. μ-EMEs were initiated by application of d.c. electric potential to the terminal aqueous solutions and specific μ-EME parameters were optimized in order to ensure complete transfer of model analytes from donor to acceptor solution. Exhaustive μ-EMEs of three basic drugs, nortriptyline, papaverine and haloperidol, were achieved from 1.3 μL of acidified donor solution (10 mM HCl) across 2.5 μL of FLM (1-ethyl-2-nitrobenzene) into 1.3 μL of acidified acceptor solution (25 mM HCl) in 10 min at 150 V. The three drugs were also exhaustively extracted from salt- and protein-containing standard solutions, human urine and human plasma with extraction recoveries ranging from 79 to 102%. Resulting acceptor solutions were analysed by capillary electrophoresis with ultraviolet detection (CE-UV) and the μ-EME-CE-UV method was characterized by good linearity (coefficients of determination ≥ 0.992), high repeatability (RSD values ≤ 6.5%) and limits of detection ≤ 0.15 mg/L.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.11.081
      Issue No: Vol. 1005 (2018)
       
  • Ionic liquid based ultrasound assisted dispersive liquid-liquid
           micro-extraction for simultaneous determination of 15 neurotransmitters in
           rat brain, plasma and cell samples
    • Authors: Rakesh Roshan Jha; Chetna Singh; Aditya B. Pant; Devendra K. Patel
      Pages: 43 - 53
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): Rakesh Roshan Jha, Chetna Singh, Aditya B. Pant, Devendra K. Patel
      Neurotransmitters are signaling molecules which play a key role in the central nervous system allowing signal transmission in the neuronal synapses. The role of these compounds is very crucial in the biological systems. A rapid, sensitive, economical and derivatisation free method has been developed for the analysis of 15 neurotransmitters in a single run on liquid chromatography tandem mass spectrometry. These 15 neurotransmitters are categorized into 5 groups on the basis of their fragmentation pattern. The proposed method “ionic liquid based ultrasound assisted dispersive liquid-liquid microextraction” hyphenated with tandem mass spectrometry is the first report for the analysis of neurotransmitters in cell samples along with other two matrices (rat brain and plasma). All the parameters that influence the extraction efficiency are optimized with aid of response surface methodology and desirability profile. Under these optimized conditions the developed method has been validated. The limit of detection was in the range of (1) 0.021–0.912 μg L−1 for rat brain samples, (2) 0.028–0.978 μg L−1 for plasma samples and (3) 0.025–0.945 μg L−1 for cell samples with good linearity behavior for all analytes in the concentration range of 0.04–200 μg L−1 in all the three matrices. The coefficient of determination for all the neurotransmitters was found in the range of (1) (R2) ≥ 0.996 to 0.999 for rat brain samples and (2) (R2) ≥ 0.991 to 0.999 for plasma and cell samples. The intra-day and inter-day variations were found less than (1) 1.78% and 8.94% for rat brain samples, (2) 1.83% and 8.37% for plasma samples and (3) 1.64% and 8.04% for cell samples respectively. The method has mean recoveries varied between (1) 81–128% for brain samples, (2) 88–107% for plasma samples and (3) 91–104% for cell samples at different spiking levels. The optimized and validated method was found free from matrix interferences and successfully applied for quantitative determination of 15 neurotransmitters in the rat brain, plasma and cell samples.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.015
      Issue No: Vol. 1005 (2018)
       
  • Sodium dodecyl sulfate removal during electrospray ionization using
           cyclodextrins as simple sample solution additive for improved mass
           spectrometric detection of peptides
    • Authors: Joselito P. Quirino
      Pages: 54 - 60
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): Joselito P. Quirino
      Sodium dodecyl sulfate (SDS) removal is a vital procedure in SDS-assisted bottom-up proteomics because SDS affects the quality of the data in electrospray ionization mass spectrometry (ESI-MS). SDS removal methods provide efficient removal of SDS and improved peptide analysis, but would usually require time, specialised devices, and experienced analysts. Here, by simple addition of γ-cyclodextrin (γ-CD) to the solution at concentrations 1 to 2x the SDS in the sample, the SDS related signals in positive ionization ESI-MS can be significantly removed (70–99% reduction), without an additional sample manipulation step of extraction or purification. The mechanism for removal is based on the formation of tightly bound CD-SDS inclusion complexes, which hampered the generation of positively charged SDS multimers during ESI. For a sample with peptides (glu-val-phe, tyr-tyr-tyr, and bradykinin) and 3 mM SDS where 6 mM γ-CD was added, the %signal recoveries of peptides calculated by comparison with signals from standard samples without SDS were 49–59%. The space charge effect by SDS on bradykinin was also reduced, increasing the signal for bradykinin 12x in the presence of γ-CD. For a protein (bovine serum albumin, BSA) digest with 3 mM SDS, which is an expected concentration in trypsin treated samples, a noticeable 7-fold improvement in the peptide to SDS signal ratio and a 91% reduction of SDS signals were observed upon addition of 6 mM γ-CD. However, there were only small changes in the ESI-MS intensities for the BSA peptides (compared to without addition of γ-CD). This new approach to SDS signal removal using CDs in ESI-MS may find use in proteomic studies.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.012
      Issue No: Vol. 1005 (2018)
       
  • Integration of paper-based microarray and time-of-flight secondary ion
           mass spectrometry (ToF-SIMS) for parallel detection and quantification of
           molecules in multiple samples automatically
    • Authors: Kuo-Jui Chu; Po-Chun Chen; Yun-Wen You; Hsun-Yun Chang; Wei-Lun Kao; Yi-Hsuan Chu; Chen-Yi Wu; Jing-Jong Shyue
      Pages: 61 - 69
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): Kuo-Jui Chu, Po-Chun Chen, Yun-Wen You, Hsun-Yun Chang, Wei-Lun Kao, Yi-Hsuan Chu, Chen-Yi Wu, Jing-Jong Shyue
      With its low-cost fabrication and ease of modification, paper-based analytical devices have developed rapidly in recent years. Microarrays allow automatic analysis of multiple samples or multiple reactions with minimal sample consumption. While cellulose paper is generally used, its high backgrounds in spectrometry outside of the visible range has limited its application to be mostly colorimetric analysis. In this work, glass-microfiber paper is used as the substrate for a microarray. The glass-microfiber is essentially chemically inert SiOx, and the lower background from this inorganic microfiber can avoid interference from organic analytes in various spectrometers. However, generally used wax printing fails to wet glass microfibers to form hydrophobic barriers. Therefore, to prepare the hydrophobic-hydrophilic pattern, the glass-microfiber paper was first modified with an octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) to make the paper hydrophobic. A hydrophilic microarray was then prepared using a CO2 laser scriber that selectively removed the OTS layer with a designed pattern. One microliter of aqueous drops of peptides at various concentrations were then dispensed inside the round patterns where OTS SAM was removed while the surrounding area with OTS layer served as a barrier to separate each drop. The resulting specimen of multiple spots was automatically analyzed with a time-of-flight secondary ion mass spectrometer (ToF-SIMS), and all of the secondary ions were collected. Among the various cluster ions that have developed over the past decade, pulsed C60 + was selected as the primary ion because of its high secondary ion intensity in the high mass region, its minimal alteration of the surface when operating within the static-limit and spatial resolution at the ∼μm level. In the resulting spectra, parent ions of various peptides (in the forms [M+H]+ and [M+Na]+) were readily identified for parallel detection of molecules in a mixture. By normalizing the ion intensity of peptides with respect to the glass-microfiber matrix ([SiOH]+), a linear calibration curve for each peptide was generated to quantify these components in a mixture.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.017
      Issue No: Vol. 1005 (2018)
       
  • Attenuated Total Reflectance Fourier Transformation Infrared spectroscopy
           fingerprinted online monitoring of the kinetics of circulating
           Butyrylcholinesterase enzyme during metabolism of bambuterol
    • Authors: Sherif M. Eid; Mohamed K. Abd El-Rahman; Mohamed R. Elghobashy; Khadiga M. Kelani
      Pages: 70 - 80
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): Sherif M. Eid, Mohamed K. Abd El-Rahman, Mohamed R. Elghobashy, Khadiga M. Kelani
      We have described a continuous flow ATR-FTIR method for measuring some of the Butyrylcholinesterase enzyme kinetics (Km and Vmax). This is done by developing a circulating system to be close as much as possible to the human circulation using human serum as a source of the enzyme with adjusted pH, isotonicity and temperature to give the maximum affinity of the enzyme towards its substrate (bambuterol). The experiment was running continuously for 90 min to monitor the production of terbutaline from the zero time of its appearance with a measured spectrum in each minute using ZnSe prism. The method was selective and successful for determination of Vmax to be 8.16 × 10−8 mol/min/ml and Km to be 2.28 × 10−5 mol, showing high affinity of the enzyme towards its prodrug substrate Bambuterol. This study critically probes the quantitative ability of the ATR-FTIR method for terbutaline, which was validated according to ICH guidelines showing high accuracy 100.39% and high selectivity towards the produced terbutaline, as the produced spectrums considered as fingerprint of each compound.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.011
      Issue No: Vol. 1005 (2018)
       
  • A new 3D printed radial flow-cell for chemiluminescence detection:
           Application in ion chromatographic determination of hydrogen peroxide in
           urine and coffee extracts
    • Authors: Vipul Gupta; Parvez Mahbub; Pavel N. Nesterenko; Brett Paull
      Pages: 81 - 92
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): Vipul Gupta, Parvez Mahbub, Pavel N. Nesterenko, Brett Paull
      A new polymer flow-cell for chemiluminescence detection (CLD) has been designed and developed by diverging multiple linear channels from a common centre port in a radial arrangement. The fabrication of radial flow-cell by 3D PolyJet printing and fused deposition modeling (FDM) has been evaluated, and compared with a similarly prepared spiral flow-cell design commonly used in chemiluminescence detectors. The radial flow-cell required only 10 h of post-PolyJet print processing time as compared to ca. 360 h long post-PolyJet print processing time required for the spiral flow-cell. Using flow injection analysis, the PolyJet 3D printed radial flow-cell provided an increase in both the signal magnitude and duration, with an average increase in the peak height of 63% and 58%, peak area of 89% and 90%, and peak base width of 41% and 42%, as compared to a coiled-tubing spiral flow-cell and the PolyJet 3D printed spiral flow-cell, respectively. Computational fluid dynamic (CFD) simulations were applied to understand the origin of the higher CLD signal obtained with the radial flow-cell design, indicating higher spatial coverage near the inlet and lower linear velocities in the radial flow-cell. The developed PolyJet 3D printed radial flow-cell was applied in a new ion chromatography chemiluminescence based assay for the detection of H2O2 in urine and coffee extracts.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.039
      Issue No: Vol. 1005 (2018)
       
  • SERS of cells: What can we learn from cell lysates'
    • Authors: E. Genova; M. Pelin; G. Decorti; G. Stocco; V. Sergo; A. Ventura; A. Bonifacio
      Pages: 93 - 100
      Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005
      Author(s): E. Genova, M. Pelin, G. Decorti, G. Stocco, V. Sergo, A. Ventura, A. Bonifacio
      Surface-enhanced Raman spectroscopy (SERS) is a promising and emerging technique to analyze the cellular environment. We developed an alternative, rapid and label-free SERS-based method to get information about the cellular environment by analyzing cells lysates, thus avoiding the need to incorporate nanoparticles into cells. Upon sonicating and filtrating cells, we obtained lysates which, mixed with Au or Ag nanoparticles, yield stable and repeatable SERS spectra, whose overall profile depends on the metal used as substrate, but not on the buffer used for the lysis process. Bands appearing in these spectra were shown to arise mostly from the cytosol and were assigned to adenine, guanine, adenosine and reduced glutathione (GSH). Spectral differences among various cell types also demonstrated that this approach is suitable for cell type identification.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.002
      Issue No: Vol. 1005 (2018)
       
  • A detailed electrochemical impedance spectroscopy study of a bismuth-film
           glassy carbon electrode for trace metal analysis
    • Authors: Barbara Petovar; Klodian Xhanari; Matjaž Finšgar
      Pages: 10 - 21
      Abstract: Publication date: 3 April 2018
      Source:Analytica Chimica Acta, Volume 1004
      Author(s): Barbara Petovar, Klodian Xhanari, Matjaž Finšgar
      A systematic electrochemical impedance spectroscopy (EIS) analysis at different potentials of an in situ-prepared bismuth-film glassy carbon electrode (BiFE) in 0.1 M acetate buffer solution is reported. This electrode is employed in the square-wave anodic stripping voltammetry (SWASV) technique for the determination of trace amounts of the heavy metals Zn, Cd, and Pb. The method was first validated for detection limit, linear range, sensitivity, precision and accuracy to clearly prove the superior action of BiFE compared with the bare glassy carbon electrode (GCE). Next, in order to investigate the characteristics of this sensor, EIS measurements were carried out at slightly more negative potentials than the potentials at which each individual stripping signal is detected, after the deposition step at different deposition potentials. For comparison, EIS measurements were also performed at open circuit potential. The studied trace metal concentration range (5–20 ppb) did not significantly influence the capacitive and resistive behaviour of the BiFE which explains why the performance of this sensor is superior compared with the bare GCE. The higher sensitivity of the SWASV method for BiFE compared with the bare GCE was explained by the lower polarisation resistance values of the former. Moreover, the potential of zero charge was also determined, and an explanation whether the system is under kinetic- and/or diffusion-controlled process is given.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.020
      Issue No: Vol. 1004 (2018)
       
  • Low-cost and disposable sensors for the simultaneous determination of
           coenzyme Q10 and α-lipoic acid using manganese (IV) oxide-modified
           screen-printed graphene electrodes
    • Authors: Kanokwan Charoenkitamorn; Sudkate Chaiyo; Orawon Chailapakul; Weena Siangproh
      Pages: 22 - 31
      Abstract: Publication date: 3 April 2018
      Source:Analytica Chimica Acta, Volume 1004
      Author(s): Kanokwan Charoenkitamorn, Sudkate Chaiyo, Orawon Chailapakul, Weena Siangproh
      In this work, for the first time, manganese (IV) oxide-modified screen-printed graphene electrodes (MnO2/SPGEs) were developed for the simultaneous electrochemical detection of coenzyme Q10 (CoQ10) and α-lipoic acid (ALA). This sensor exhibits attractive benefits such as simplicity, low production costs, and disposability. Cyclic voltammetry (CV) was used to characterize the electrochemical behavior of the analyte and investigate the capacitance and electroactive surface area of the unmodified and modified electrode surfaces. The electrochemical behavior of CoQ10 and ALA on MnO2/SPGEs was also discussed. Additionally, square wave anodic stripping voltammetry (SWASV) was used for the quantitative determination of CoQ10 and ALA. Under optimal conditions, the obtained signals are linear in the concentration range from 2.0 to 75.0 μg mL−1 for CoQ10 and 0.3–25.0 μg mL−1 for ALA. The low limits of detection (LODs) were found to be 0.56 μg mL−1 and 0.088 μg mL−1 for CoQ10 and ALA, respectively. Moreover, we demonstrated the utility and applicability of the MnO2/SPGE sensor through simultaneous measurements of CoQ10 and ALA in dietary supplements. The sensor provides high accuracy measurements, exhibiting its high potential for practical applications.
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      PubDate: 2018-02-05T13:50:05Z
      DOI: 10.1016/j.aca.2017.12.026
      Issue No: Vol. 1004 (2018)
       
  • Outside Front Cover - Journal name, Cover image, Volume issue details,
           ISSN, Cover Date, Elsevier Logo and Society Logo if required
    • Abstract: Publication date: 30 May 2018
      Source:Analytica Chimica Acta, Volume 1008


      PubDate: 2018-02-05T13:50:05Z
       
  • Outside Front Cover - Journal name, Cover image, Volume issue details,
           ISSN, Cover Date, Elsevier Logo and Society Logo if required
    • Abstract: Publication date: 12 May 2018
      Source:Analytica Chimica Acta, Volume 1007


      PubDate: 2018-02-05T13:50:05Z
       
  • Outside Front Cover - Journal name, Cover image, Volume issue details,
           ISSN, Cover Date, Elsevier Logo and Society Logo if required
    • Abstract: Publication date: 16 April 2018
      Source:Analytica Chimica Acta, Volume 1005


      PubDate: 2018-02-05T13:50:05Z
       
  • Outside Front Cover - Journal name, Cover image, Volume issue details,
           ISSN, Cover Date, Elsevier Logo and Society Logo if required
    • Abstract: Publication date: 3 April 2018
      Source:Analytica Chimica Acta, Volume 1004


      PubDate: 2018-02-05T13:50:05Z
       
  • Unattended reaction monitoring using an automated microfluidic sampler and
           on-line liquid chromatography
    • Abstract: Publication date: 3 April 2018
      Source:Analytica Chimica Acta, Volume 1004
      Author(s): Darshan C. Patel, Yaqi "Fara" Lyu, Jorge Gandarilla, Steve Doherty
      In-process sampling and analysis is an important aspect of monitoring kinetic profiles and impurity formation or rejection, both in development and during commercial manufacturing. In pharmaceutical process development, the technology of choice for a substantial portion of this analysis is high-performance liquid chromatography (HPLC). Traditionally, the sample extraction and preparation for reaction characterization have been performed manually. This can be time consuming, laborious, and impractical for long processes. Depending on the complexity of the sample preparation, there can be variability introduced by different analysts, and in some cases, the integrity of the sample can be compromised during handling. While there are commercial instruments available for on-line monitoring with HPLC, they lack capabilities in many key areas. Some do not provide integration of the sampling and analysis, while others afford limited flexibility in sample preparation. The current offerings provide a limited number of unit operations available for sample processing and no option for workflow customizability. This work describes development of a microfluidic automated program (MAP) which fully automates the sample extraction, manipulation, and on-line LC analysis. The flexible system is controlled using an intuitive Microsoft Excel based user interface. The autonomous system is capable of unattended reaction monitoring that allows flexible unit operations and workflow customization to enable complex operations and on-line sample preparation. The automated system is shown to offer advantages over manual approaches in key areas while providing consistent and reproducible in-process data.
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
       
  • Simultaneous determination of 117 pesticides and 30 mycotoxins in raw
           coffee, without clean-up, by LC-ESI-MS/MS analysis
    • Abstract: Publication date: 3 April 2018
      Source:Analytica Chimica Acta, Volume 1004
      Author(s): Bárbara Reichert, André de Kok, Ionara Regina Pizzutti, Jos Scholten, Carmem Dickow Cardoso, Martien Spanjer
      This paper describes the optimization and validation of an acetonitrile based method for simultaneous extraction of multiple pesticides and mycotoxins from raw coffee beans followed by LC-ESI-MS/MS determination. Before extraction, the raw coffee samples were milled and then slurried with water. The slurried samples were spiked with two separate standard solutions, one containing 131 pesticides and a second with 35 mycotoxins, which were divided into 3 groups of different relative concentration levels. Optimization of the QuEChERS approach included performance tests with acetonitrile acidified with acetic acid or formic acid, with or without buffer and with or without clean-up of the extracts before LC-ESI-MS/MS analysis. For the clean-up step, seven d-SPE sorbents and their various mixtures were evaluated. After method optimization a complete validation study was carried out to ensure adequate performance of the extraction and chromatographic methods. The samples were spiked at 3 concentrations levels with both mycotoxins and pesticides (with 6 replicates at each level, n = 6) and then submitted to the extraction procedure. Before LC-ESI-MS/MS analysis, the acetonitrile extracts were diluted 2-fold with methanol, in order to improve the chromatographic performance of the early-eluting polar analytes. Calibration standard solutions were prepared in organic solvent and in blank coffee extract at 7 concentration levels and analyzed 6 times each. The method was assessed for accuracy (recovery %), precision (RSD%), selectivity, linearity (r2), limit of quantification (LOQ) and matrix effects (%).
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
       
  • Detection of native proteins using solid-substrate electrospray ionization
           mass spectrometry with nonpolar solvents
    • Abstract: Publication date: 3 April 2018
      Source:Analytica Chimica Acta, Volume 1004
      Author(s): Bin Hu, Zhong-Ping Yao
      Detection of native proteins, particularly directly from raw biological samples, has been a challenging task for mass spectrometry. In this study, we demonstrated that solid-substrate electrospray ionization mass spectrometry with nonpolar solvents such as n-hexane could allow detection of native proteins and protein complexes directly from raw biological samples. Mechanistic study revealed that the process involved rapid vaporization of the nonpolar solvent, temperature reduction of substrate surface, condensation of water from the ambient air, and spray ionization of the condensed water with analytes under the electric field. The fine spray with water at low temperature allowed the technique to detect native proteins, even directly from viscous samples (e.g., egg white) and solid samples (e.g., bone marrow). This study sheds new insight into the sampling and ionization process of mass spectrometry and provides a technique of great potential for characterization of proteins.
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
       
  • Characterization of singly and multiply PEGylated insulin isomers by
           reversed-phase ultra-performance liquid chromatography interfaced with ion
           mobility mass spectrometry
    • Abstract: Publication date: 3 April 2018
      Source:Analytica Chimica Acta, Volume 1004
      Author(s): Selim Gerislioglu, Scott R. Adams, Chrys Wesdemiotis
      Conjugation of poly(ethylene glycol) (PEG) to protein drugs (PEGylation) is increasingly utilized in the biotherapeutics field because it improves significantly the drugs' circulatory half-life, solubility, and shelf-life. The activity of a PEGylated drug depends on the number, size, and location of the attached PEG chain(s). This study introduces a 2D separation approach, including reversed-phase ultra-performance liquid chromatography (RP-UPLC) and ion mobility mass spectrometry (IM-MS), in order to determine the structural properties of the conjugates, as demonstrated for a PEGylated insulin sample that was prepared by random amine PEGylation. The UPLC dimension allowed separation based on polarity. Electrospray ionization (ESI) of the eluates followed by in-source dissociation (ISD) truncated the PEG chains and created insulin fragments that provided site-specific information based on whether they contained a marker at the potential conjugation sites. Separation of the latter fragments by size and charge in the orthogonal IM dimension (pseudo-4D UPLC-ISD-IM-MS approach) enabled clear detection and identification of the positional isomers formed upon PEGylation. The results showed a highly heterogeneous mixture of singly and multiply conjugated isomers plus unconjugated material. PEGylation was observed on all three possible attachment sites (ε-NH2 of LysB29, A- and B-chain N-termini). Each PEGylation site was validated by analysis of the same product after disulfide bond cleavage, so that the PEGylated A- and B- chain could be individually characterized with the same pseudo-4D UPLC-ISD-IM-MS method.
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
       
  • Hydride generation coupled with thioglycolic acid coated gold
           nanoparticles as simple and sensitive headspace colorimetric assay for
           visual detection of Sb(III)
    • Abstract: Publication date: 3 April 2018
      Source:Analytica Chimica Acta, Volume 1004
      Author(s): Tesfaye Tolessa, Zhi-Qiang Tan, Jing-Fu Liu
      Antimony (Sb) is a toxic element which causes different health problems including cardiac problems and lung cancer in humans, and its levels in surface water can be noticeably increased to 100 μg/L typically in the proximity of anthropogenic sources. Thus, besides instrumental techniques, it is of great significance to develop a simple, sensitive and selective analytical method for direct analysis of Sb(III) at trace level without the need of any expensive and/or complicated instrumentations and sample preparation processes. Herein, a simple and sensitive headspace colorimetric assay was developed for the detection of Sb(III) by hydride generation coupled with thioglycolic acid functionalized gold nanoparticles (TGA-AuNPs). Sb(III) in the 30 mL sample solution was converted into its volatile form (SbH3) through hydride generation reaction and headspace extracted into 100 μL chromogenic reagent, which contains methanol as extractant and TGA-AuNPs as nanosensors, leading to aggregation of TGA-AuNPs and therefore a red-to-blue color change. Parameters influencing the chromogenic and hydride generation reactions were optimized. Addition of 300 μM ethylenediamine tetraacetic acid (EDTA) as masking agent largely suppressed the inferences from mercury and arsenic. The proposed method can tolerate at least 10-fold As(III) and 100-fold other metal ions including Hg(II). The detection limits were 6.0 and 1.2 μg/L Sb(III) by naked-eye and UV-Vis spectrometer, respectively, which meet the maximum admissible level in drinking water (6 μg/L) set by the United States Environmental Protection Agency. The feasibility of the proposed method was demonstrated by rapid detection of Sb(III) in river water, lake water, ground water and sea water samples by naked-eye at a spiking level of 6 μg/L Sb(III).
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
       
  • Colorimetric logic gate for alkaline phosphatase based on copper
           (II)-based metal-organic frameworks with peroxidase-like activity
    • Abstract: Publication date: 3 April 2018
      Source:Analytica Chimica Acta, Volume 1004
      Author(s): Caihong Wang, Jie Gao, Yili Cao, Hongliang Tan
      Nanozymes have been extensively exploited in the construction of colorimetric sensors in the past decade. However, as lack of specific recognition element, these sensors are mostly limited in the detection of hydrogen peroxide and its related agents. In this work, a colorimetric assay for the detection of alkaline phosphatase (ALP) activity was developed by employing copper (II)-based metal-organic frameworks (Cu-MOFs) as peroxidase mimic and pyrophosphate (PPi) as recognition element. Benefiting from its intrinsic porosity, Cu-MOFs built from one-step self-assembly showed a superior catalytic activity over horseradish peroxidase. It was found that, in the presence of PPi, the catalytic activity of Cu-MOFs was greatly inhibited due to the ultrastrong binding ability of Cu2+ with PPi, and no colorimetric signal was recorded. However, after incubation with ALP, such negative behavior of PPi can be suppressed as the hydrolysis of PPi into orthophosphates (Pi) with low affinity to Cu2+, producing a colorimetric signal depending on ALP level. On this basis, a way for quantitative analysis of ALP activity was paved accordingly. Compared with previously reported ALP assays based on nanomaterials, this assay is simple, cost-effective and visualized, which not only allows highly sensitive analysis of ALP activity with a detection limit of 0.19 U/L, but also exhibits a good sensing performance in serum samples. Furthermore, based on the distinct colorimetric signals induced by PPi and ALP, an IMPLICATION logic gate was constructed. We hope that this study could provide a new insight for designing nanozyme-based highly specific colorimetric sensors.
      Graphical abstract image

      PubDate: 2018-02-05T13:50:05Z
       
  • Outside Front Cover - Journal name, Cover image, Volume issue details,
           ISSN, Cover Date, Elsevier Logo and Society Logo if required
    • Abstract: Publication date: 20 March 2018
      Source:Analytica Chimica Acta, Volume 1003


      PubDate: 2018-02-05T13:50:05Z
       
  • Rotational paper-based electrochemiluminescence immunodevices for
           sensitive and multiplexed detection of cancer biomarkers
    • Authors: Xiange Sun; Bowei Li; Chunyuan Tian; Fabiao Yu; Na Zhou; Yinghua Zhan; Lingxin Chen
      Abstract: Publication date: Available online 27 December 2017
      Source:Analytica Chimica Acta
      Author(s): Xiange Sun, Bowei Li, Chunyuan Tian, Fabiao Yu, Na Zhou, Yinghua Zhan, Lingxin Chen
      This paper describes a novel rotational paper-based analytical device (RPAD) to implement multi-step electrochemiluminescence (ECL) immunoassays. The integrated paper-based rotational valves can be easily controlled by rotating paper discs manually and this advantage makes it user-friendly to untrained users to carry out the multi-step assays. In addition, the rotational valves are reusable and the response time can be shorted to several seconds, which promotes the rotational paper-based device to have great advantages in multi-step operations. Under the control of rotational valves, multi-step ECL immunoassays were conducted on the rotational device for the multiplexed detection of carcinoembryonic antigen (CEA) and prostate specific antigen (PSA). The rotational device exhibited excellent analytical performance for CEA and PSA, and they could be detected in the linear ranges of 0.1–100 ng mL−1 and 0.1–50 ng mL−1 with detection limits down to 0.07 ng mL−1 and 0.03 ng mL−1, respectively, which were within the ranges of clinical concentrations. We hope this technique will open a new avenue for the fabrication of paper-based valves and provide potential application in clinical diagnostics.
      Graphical abstract image

      PubDate: 2017-12-27T13:42:04Z
      DOI: 10.1016/j.aca.2017.12.005
       
  • Highly-sensitive microRNA detection based on bio-bar-code assay and
           catalytic hairpin assembly two-stage amplification
    • Authors: Songsong Tang; Yuan Gu; Huiting Lu; Haifeng Dong; Kai Zhang; Wenhao Dai; Xiangdan Meng; Fan Yang; Xueji Zhang
      Abstract: Publication date: Available online 19 December 2017
      Source:Analytica Chimica Acta
      Author(s): Songsong Tang, Yuan Gu, Huiting Lu, Haifeng Dong, Kai Zhang, Wenhao Dai, Xiangdan Meng, Fan Yang, Xueji Zhang
      Herein, a highly-sensitive microRNA (miRNA) detection strategy was developed by combining bio-bar-code assay (BBA) with catalytic hairpin assembly (CHA). In the proposed system, two nanoprobes of magnetic nanoparticles functionalized with DNA probes (MNPs-DNA) and gold nanoparticles with numerous barcode DNA (AuNPs-DNA) were designed. In the presence of target miRNA, the MNP-DNA and AuNP-DNA hybridized with target miRNA to form a “sandwich” structure. After “sandwich” structures were separated from the solution by the magnetic field and dehybridized by high temperature, the barcode DNA sequences were released by dissolving AuNPs. The released barcode DNA sequences triggered the toehold strand displacement assembly of two hairpin probes, leading to recycle of barcode DNA sequences and producing numerous fluorescent CHA products for miRNA detection. Under the optimal experimental conditions, the proposed two-stage amplification system could sensitively detect target miRNA ranging from 10 pM to 10 aM with a limit of detection (LOD) down to 97.9 zM. It displayed good capability to discriminate single base and three bases mismatch due to the unique sandwich structure. Notably, it presented good feasibility for selective multiplexed detection of various combinations of synthetic miRNA sequences and miRNAs extracted from different cell lysates, which were in agreement with the traditional polymerase chain reaction analysis. The two-stage amplification strategy may be significant implication in the biological detection and clinical diagnosis.
      Graphical abstract image

      PubDate: 2017-12-27T13:42:04Z
      DOI: 10.1016/j.aca.2017.12.004
       
 
 
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