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https://www.readbyqxmd.com/read/28780867/electroanalysis-of-neutral-precursors-in-protic-ionic-liquids-and-synthesis-of-high-ionicity-ionic-liquids
#1
Sean E Goodwin, Daniel E Smith, Joshua S Gibson, Robert George Jones, Darren Anthony Walsh
Protic ionic liquids (PILs) are ionic liquids that are formed by transferring protons from Brønsted acids to Brønsted bases. While they nominally consist entirely of ions, PILs can often behave as though they contain a significant amount of neutral species (either molecules or ion clusters), and there is currently a lot of interest in determining the degree of "ionicity" of PILs. In this contribution, we describe a simple electroanalytical method for detecting and quantifying residual excess acids in a series of ammonium-based PILs (diethylmethylammonium triflate, [dema][TfO], dimethylethylammonium triflate, [dmea][TfO], triethylammonium trifluoroacetate, [tea][TfAc], and dimethylbutylammonium triflate [dmba][TfO])...
August 7, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28763958/electroanalysis-and-laccase-based-biosensor-on-the-determination-of-phenolic-content-and-antioxidant-power-of-honey-samples
#2
Jerônimo Raimundo de Oliveira Neto, Stefani Garcia Rezende, Gérman Sanz Lobón, Telma Alves Garcia, Isaac Yves Lopes Macedo, Luane Ferreira Garcia, Virgínia Farias Alves, Ieda Maria Sapateiro Torres, Mariângela Fontes Santiago, Fernando Schmidt, Eric de Souza Gil
Honey is a functional food widely consumed. Thus, the evaluation of honey samples to determine its phenolic content and antioxidant capacity (AOC) is relevant to determine its quality. Usually AOC is performed by spectrophotometric methods, which lacks reproducibility and practicality. In this context, the electroanalytical methods offer higher simplicity and accuracy. Hence, the aim of this work was to use of electroanalytical tools and laccase based biosensor on the evaluation of AOC and total phenol content (TPC) of honey samples from different countries...
December 15, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28742317/disposable-microfluidic-immunoarray-device-for-sensitive-breast-cancer-biomarker-detection
#3
Ricardo A G de Oliveira, Elsa María Materón, Matias Eliseo Melendez, Andre L Carvalho, Ronaldo C Faria
Breast cancer is the most common cancer in women worldwide. The detection of biomarkers has played a significant role in the early diagnosis and prognosis of breast cancer. Herein, we describe the construction of a disposable microfluidic immunoarray device (DµID) for rapid and low-cost detection of CA15-3 a protein biomarker for breast cancer. The DµID was constructed using a simple and rapid prototyping technique and was applied to detect CA15-3 in cancer patients. The DµID construction was based on a use of double-sided adhesive card with the microfluidic channel and a screen-printed array with 8 electrodes...
July 25, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28738575/analytical-methodology-for-the-electro-catalytic-determination-of-estradiol-and-progesterone-based-on-graphene-quantum-dots-and-poly-sulfosalicylic-acid-co-modified-electrode
#4
Majid Arvand, Shiva Hemmati
The goal of this study was to develop an electroanalytical method for the simultaneous determination of steroid hormones for the first time. The key factor in the electrochemical methods is the choice of suitable electrode materials. For this purpose, graphene quantum dots (GQDs) doped poly(sulfosalicylic acid) (PSSA) was immobilized on a glassy carbon electrode (GCE). Apart from exhibition strong and stable electrocatalytic response towards estradiol (E2) and progesterone (P4), the proposed sensor was able to distinguish two hormone's oxidation peaks clearly...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28732345/multichannel-electroanalytical-devices-for-competitive-elisa-of-phenylethanolamine-a
#5
Yang Liu, Meng Cai, Weiping Wu, Yuting Fang, Pei She, Shouming Xu, Jianguo Li, Kang Zhao, Jingjuan Xu, Ning Bao, Anping Deng
Herein, we reported a disposable electroanalytical device for competitive enzyme-linked immunosorbent assay (ELISA) of phenylethanolamine A (PA). Conductive carbon tape coated with gold cluster served as the working electrode, while the counter and reference electrodes were fabricated on the filter paper by the screen-printing technique. Separating fabrication of the working electrode from other electrodes could make it possible for full utilization of the working electrode modification in bulk and no contamination of the immune-reagents on the counter and reference electrodes...
April 11, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28723196/label-free-homogeneous-electroanalytical-platform-for-pesticide-detection-based-on-acetylcholinesterase-mediated-dna-conformational-switch-integrated-with-rolling-circle-amplification
#6
Xiaojuan Liu, Mengmeng Song, Ting Hou, Feng Li
This study addresses the need for sensitive pesticide assay by reporting a new label-free and immobilization-free homogeneous electroanalytical strategy, which combines acetylcholinesterase (AChE)-catalyzed hydrolysis product-mediated DNA conformational switch and rolling circle amplification (RCA) to detect organophosphorous and carbamate pesticides in a "signal-on" mode. When target pesticides were present, AChE activity was inhibited and could not trigger the following DNA conformational change and the RCA reaction, which results in numerous methylene blue (MB) molecules in a free state, generating a strong electrochemical response...
April 28, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28700826/application-of-coal-in-electrochemical-sensing
#7
Jianzhi Huang, Qiang Zeng, Silan Bai, Lishi Wang
In this work, we first report a new application of coal as a novel modified electrode material in electrochemical sensing, achieving excellent electrochemical performance similar to graphene and making the utilization of coal become more multipurpose and more meaningful. Raw coal was first ball-milled, then centrifugated, and finally annealed, thus obtaining annealed coal that possesses lots of edge-plane-like defective sites, resulting in good electron-transfer efficiency and excellent electrocatalytic activity, which makes it promising when used as signal amplifier material and as a modified matrix in electrochemical sensing...
July 26, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28697443/selective-binding-of-pb-2-with-manganese-terephthalic-acid-mof-swcnts-theoretical-modeling-experimental-study-and-electroanalytical-application
#8
Fuxian Cai, Qinghua Wang, Xiaoqian Chen, Weiwei Qiu, Fengping Zhan, Fei Gao, Qingxiang Wang
A nanocomposite of flake-shaped manganese-terephthalic acid MOF/single-walled carbon nanotubes (Mn(TPA)-SWCNTs) was synthesized using manganese chloride, terephthalic acid and SWCNTs as raw materials. Theoretical modeling study shows that the Mn(TPA) component has stronger adsorption ability to lead ion (Pb(2+)) than the other common heavy metal ions, which is in good agreement with the result of electrochemical assay. Then, the Mn(TPA)-SWCNTs were used as a sensing matrix for the voltammetric determination of Pb(2+)...
July 6, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28693726/point-of-need-simultaneous-electrochemical-detection-of-lead-and-cadmium-using-low-cost-stencil-printed-transparency-electrodes
#9
Daniel Martín-Yerga, Isabel Álvarez-Martos, M Carmen Blanco-López, Charles S Henry, M Teresa Fernández-Abedul
In this work, we report a simple and yet efficient stencil-printed electrochemical platform that can be integrated into the caps of sample containers and thus, allows in-field quantification of Cd(II) and Pb(II) in river water samples. The device exploits the low-cost features of carbon (as electrode material) and paper/polyester transparency sheets (as substrate). Electrochemical analysis of the working electrodes prepared on different substrates (polyester transparency sheets, chromatographic, tracing and office papers) with hexaammineruthenium(III) showed that their electroactive area and electron transfer kinetics are highly affected by the porosity of the material...
August 15, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28674450/triplex-dna-based-bioanalytical-platform-for-highly-sensitive-homogeneous-electrochemical-detection-of-melamine
#10
Xiaojuan Liu, Mengmeng Song, Feng Li
Melamine detection has attracted much attention since the discovery of the damage of melamine to human health. Herein, we have developed a sensitive homogeneous electroanalytical platform for melamine detection, which is relied on the formation of triplex molecular beacon integrated with exonuclease III (Exo III)-mediated signal amplification. The formation of triplex molecular beacon was triggered by the recognition and incorporation of melamine to the abasic (AP) site contained in the triplex stem. The stem of the triplex molecular beacon was designed to have a protruding double-strand DNA, which can be recognized and hydrolyzed by Exo III for releasing methylene blue (MB)-labeled mononucleotide...
July 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28672191/tear-glucose-detection-combining-microfluidic-thread-based-device-amperometric-biosensor-and-microflow-injection-analysis
#11
Deonir Agustini, Márcio F Bergamini, Luiz Humberto Marcolino-Junior
The tear glucose analysis is an important alternative for the indirect, simple and less invasive monitoring of blood glucose levels. However, the high cost and complex manufacturing process of tear glucose analyzers combined with the need to exchange the sensor after each analysis in the disposable tests prevent widespread application of the tear in glucose monitoring. Here, we present the integration of a biosensor made by the electropolymerization of poly(toluidine blue O) (PTB) and glucose oxidase (GOx) with an electroanalytical microfluidic device of easy assembly based on cotton threads, low cost materials and measurements by microflow injection analysis (µFIA) through passive pumping for performing tear glucose analyses in a simple, rapid and inexpensive way...
June 22, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28664333/preparation-of-electrochemically-treated-nanoporous-pencil-graphite-electrodes-for-the-simultaneous-determination-of-pb-and-cd-in-water-samples
#12
Koray B Dönmez, Ebru Çetinkaya, Seda Deveci, Sevinç Karadağ, Yücel Şahin, Mustafa Doğu
A simple and rapid analytical method of determining Pb(2+) and Cd(2+) in water samples using an electrochemically pretreated pencil-graphite electrode (EP-PGE) is proposed for the first time in the literature. An electrochemically pretreated pencil-graphite electrode was prepared by performing potential cycling between -0.3 V and 2.0 V in 0.1 mol L(-1) H3PO4 solution to improve its ability to electrochemically sense Pb(2+) and Cd(2+) ions. Square-wave anodic stripping voltammetry (SWASV) was used as the electroanalytical method...
June 29, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28654289/oxidation-of-natural-bioactive-flavonolignan-2-3-dehydrosilybin-an-electrochemical-and-spectral-study
#13
Romana Sokolová, Jana Kocábová, Petr Marhol, Jan Fiedler, David Biedermann, Jan Vacek, Vladimír Křen
The electrochemical oxidation of the natural antioxidant 2,3-dehydrosilybin (DHS) was investigated in acetonitrile. The spectral changes during two electron and two proton oxidation registered by in situ IR spectroelectrochemistry show that the electron transfer is followed by a subsequent chemical reaction with traces of water. A benzofuranone derivative (BF) is formed by ECEC (electron transfer-chemical reaction-electron transfer-chemical reaction) process at the potential of the first oxidation wave. A minor difference in the chemical structures of flavonolignans DHS and silybin, the presence of a double bond between atoms C-2 and C-3 in the DHS molecule, causes the formation of completely different oxidation products...
July 11, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28629040/3-aminopropyltrimethoxysilane-mediated-solvent-induced-synthesis-of-gold-nanoparticles-for-biomedical-applications
#14
Prem C Pandey, Gunjan Pandey, Alain Walcarius
The effect of acetone on 3-aminopropyltrimethoxysilane (3-APTMS) mediated synthesis of gold nanoparticles (AuNPs) in polar protic, polar aprotic and non polar solvents specifically water, acetone and chloroform has been studied. The findings revealed that acetone promotes the formation of siloxane polymer in chloroform and acetone solvents, but not in water, while AuNPs are formed in all cases. The bifunctional nature of 3-APTMS [NH2(CH2)3Si(OMe)3] controls the formation of siloxane polymer through hydrolysis and condensation of trimethoxysilyl group whereas the amine moieties are likely to form imine linkage, which are involved in the synthesis of gold nanoparticles...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28627895/electroanalytical-assessment-of-the-effect-of-ni-fe-stoichiometry-and-architectural-expression-on-the-bifunctional-activity-of-nanoscale-niyfe1-yox
#15
Jesse S Ko, Christopher N Chervin, Mallory N Vila, Paul A DeSario, Joseph F Parker, Jeffrey W Long, Debra R Rolison
Electrocatalysis of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) was assessed for a series of Ni-substituted ferrites (NiyFe1-yOx, where y = 0.1 to 0.9) as expressed in porous, high-surface-area forms (ambigel and aerogel nanoarchitectures). We then correlate electrocatalytic activity with Ni:Fe stoichiometry as a function of surface area, crystallite size, and free volume. In order to ensure in-series comparisons, calcination at 350 °C/air was necessary to crystallize the respective NiyFe1-yOx nanoarchitectures, which index to the inverse spinel structure for Fe-rich materials (y ≤ 0...
June 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28621385/electroanalytical-determination-of-escitalopram-oxalate-using-nickel-nanoparticles-modified-carbon-paste-sensor
#16
Kamal Attia, A Mona Mohamed, M Amany Fekry
A sensitive voltammetric method was described for the determination of escitalopram oxalate based on electrocatalytic oxidation at nickel nanoparticles modified chloranil carbon paste sensor in Britton-Robinson buffer (pH range from 2 to 10). The modified electrode was characterized by scanning electron microscopy, electrochemical impedance and cyclic voltammetry. The investigation of electrochemical behavior of escitalopram oxalate was performed using cyclic voltammetry and differential pulse voltammetry. The anodic peak current showed a linear range from 1...
June 2017: Acta Chimica Slovenica
https://www.readbyqxmd.com/read/28621134/surfactant-and-binder-free-hierarchical-platinum-nanoarrays-directly-grown-onto-a-carbon-felt-electrode-for-efficient-electrocatalysis
#17
Widya Ernayati Kosimaningrum, Thi Xuan Huong Le, Yaovi Holade, Mikhael Bechelany, Sophie Tingry, Buchari Buchari, Indra Noviandri, Christophe Innocent, Marc Cretin
The future of fuel cells that convert chemical energy to electricity relies mostly on the efficiency of oxygen reduction reaction (ORR) due to its sluggish kinetics. By effectively bypassing the use of organic surfactants, the postsynthesis steps for immobilization onto electrodes, catalytic ink preparation using binders, and the common problem of nanoparticles (NPs) detachment from the supports involved in traditional methodologies, we demonstrate a versatile electrodeposition method for growing anisotropic microstructures directly onto a three-dimensional (3D) carbon felt electrode, using platinum NPs as the elementary building blocks...
July 12, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28579929/microfabricated-massive-electrochemical-arrays-of-uniform-ultramicroelectrodes
#18
Christopher Gunderson, Bo Zhang
We report the preparation and electrochemical characterization of massive electrochemical arrays containing as many as 110,000 highly uniform ultramicroelectrodes (UMEs). These arrays were microfabricated using conventional photolithography techniques on a gold-coated silicon chip in a simple three-step method. Photoresist polymer was used as an effective insulating matrix to define 2 μm, 3 μm, and 4 μm diameter circular UMEs across a 1 × 1 mm(2) area. The UME arrays are high uniform and contain tens of thousands of active disk-shape UMEs slightly recessed in thin films of photoresist...
November 15, 2016: Journal of Electroanalytical Chemistry
https://www.readbyqxmd.com/read/28548867/statins-determination-a-review-of-electrochemical-techniques
#19
I Antal, M Koneracka, V Zavisova, M Kubovcikova, Zh Kormosh, P Kopcansky
The use of electroanalytical techniques for the determination of statins (Atorvastatin, Fluvastatin, Lovastatin, Pitavastatin, Pravastatin, Rosuvastatin and Simvastatin) is reviewed covering the period from 1997 to 2016. Among all of the published electrochemical methods, voltammetry and polarography are the most popular techniques for determination of statins and both are used for the analysis of pharmaceutical dosage forms and biological samples. Determination of statins by potentiometric method using ion-selective electrodes is reported in only few papers...
May 26, 2017: Critical Reviews in Analytical Chemistry
https://www.readbyqxmd.com/read/28507703/advanced-electroanalytical-chemistry-at-nanoelectrodes
#20
Yi-Lun Ying, Zhifeng Ding, Dongping Zhan, Yi-Tao Long
Nanoelectrodes, with dimensions below 100 nm, have the advantages of high sensitivity and high spatial resolution. These electrodes have attracted increasing attention in various fields such as single cell analysis, single-molecule detection, single particle characterization and high-resolution imaging. The rapid growth of novel nanoelectrodes and nanoelectrochemical methods brings enormous new opportunities in the field. In this perspective, we discuss the challenges, advances, and opportunities for nanoelectrode fabrication, real-time characterizations and high-performance electrochemical instrumentation...
May 1, 2017: Chemical Science
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