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https://www.readbyqxmd.com/read/28448855/glassy-carbon-electrode-modified-with-7-7-8-8-tetracyanoquinodimethane-and-graphene-oxide-triggered-a-synergistic-effect-low-potential-amperometric-detection-of-reduced-glutathione
#1
Baiqing Yuan, Chunying Xu, Renchun Zhang, Donghui Lv, Sujuan Li, Daojun Zhang, Lin Liu, Carlos Fernandez
A sensitive electrochemical sensor based on the synergistic effect of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and graphene oxide (GO) for low-potential amperometric detection of reduced glutathione (GSH) in pH 7.2 phosphate buffer solution (PBS) has been reported. This is the first time that the combination of GO and TCNQ have been successfully employed to construct an electrochemical sensor for the detection of glutathione. The surface of the glassy carbon electrode (GCE) was modified by a drop casting using TCNQ and GO...
April 21, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28426249/non-enzymatic-electrochemistry-in-characterization-and-analysis-of-steroid-compounds
#2
Jan Klouda, Jiří Barek, Karel Nesměrák, Karolina Schwarzová-Pecková
This review summarizes achievements in electrochemistry-related research of steroid-based compounds in clinical, pharmaceutical, and environmental analysis. Special attention is paid to compounds possessing none or only isolated double bonds at the steroid core. Their direct redox activity is limited to far positive/negative potentials under variety of conditions and electrode materials and relies on the functional groups attached to the steroid skeleton, or as the case may be its double bond, or moieties present at the side chain...
April 20, 2017: Critical Reviews in Analytical Chemistry
https://www.readbyqxmd.com/read/28418648/a-modular-flow-through-platform-for-spectroelectrochemical-analysis
#3
Tomer Noyhouzer, Michael Edward Snowden, Ushula M Tefashe, Janine Mauzeroll
A new type of flow platform for electrochemical and spectroelectrochemical measurements is presented. Finite element method simulations confirm that the hydrodynamic profile within the device is not turbulent, and provides an analytical platform for the investigation of homogenous kinetics, radical lifetimes and reaction mechanisms. The modular "plug and play" configuration of the platform allows one to carry out electrochemistry and spectroscopy individually or simultaneously. Specific demonstrations of electroanalytical measurements using the flow system platform includes voltammetric analysis of organometallic compounds and quantitative analysis of ascorbic acid in commercial orange juice samples...
April 18, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28418064/surfactant-exfoliated-2d-hexagonal-boron-nitride-2d-hbn-explored-as-a-potential-electrochemical-sensor-for-dopamine-surfactants-significantly-influence-sensor-capabilities
#4
Aamar F Khan, Dale A C Brownson, Christopher W Foster, Graham C Smith, Craig E Banks
Surfactant exfoliated 2D hexagonal Boron Nitride (2D-hBN) nanosheets are explored as a potential electrochemical sensing platform and evaluated towards the electroanalytical sensing of dopamine (DA) in the presence of the common interferents, ascorbic acid (AA) and uric acid (UA). Surfactant exfoliated 2D-hBN nanosheets (2-4 layers) fabricated using sodium cholate in aqueous media are electrically wired via a drop-casting modification process onto disposable screen-printed graphite electrodes (SPEs). We critically evaluate the performance of these 2D-hBN modified SPEs and demonstrate the effect of 'mass coverage' towards the detection of DA, AA and UA...
April 18, 2017: Analyst
https://www.readbyqxmd.com/read/28394410/nanotechnology-for-electroanalytical-biosensors-of-reactive-oxygen-and-nitrogen-species
#5
REVIEW
Rajesh Seenivasan, Charles Kolodziej, Chandran Karunakaran, Clemens Burda
Over the past several decades, nanotechnology has contributed to the progress of biomedicine, biomarker discovery, and the development of highly sensitive electroanalytical / electrochemical biosensors for in vitro and in vivo monitoring, and quantification of oxidative and nitrosative stress markers like reactive oxygen species (ROS) and reactive nitrogen species (RNS). A major source of ROS and RNS is oxidative stress in cells, which can cause many human diseases, including cancer. Therefore, the detection of local concentrations of ROS (e...
April 10, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
https://www.readbyqxmd.com/read/28391695/simulation-based-approach-to-determining-electron-transfer-rates-using-square-wave-voltammetry
#6
Philippe Dauphin-Ducharme, Netzahualcóyotl Arroyo-Currás, Martin Kurnik, Gabriel Ortega, Hui Li, Kevin W Plaxco
The efficiency with which square-wave voltammetry differentiates faradic and charging currents makes it a particularly sensitive electroanalytical approach, as evidenced by its ability to measure nanomolar or even picomolar concentrations of electroactive analytes. Because of the relative complexity of the potential sweep it uses, however, the extraction of detailed kinetic and mechanistic information from square-wave data remains challenging. In response, we demonstrate here a numerical approach by which square-wave data can be used to determine electron transfer rates...
April 26, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28390317/a-highly-sensitive-and-selective-sensor-based-on-a-graphene-coated-carbon-paste-electrode-modified-with-a-computationally-designed-boron-embedded-duplex-molecularly-imprinted-hybrid-membrane-for-the-sensing-of-lamotrigine
#7
Hongjuan Wang, Duo Qian, Xilin Xiao, Shuqin Gao, Jianlin Cheng, Bo He, Lifu Liao, Jian Deng
An innovative electrochemical sensor, based on a carbon paste electrode (CPE) modified with graphene (GR) and a boron-embedded duplex molecularly imprinted hybrid membrane (B-DMIHM), was fabricated for the highly sensitive and selective determination of lamotrigine (LMT). Density functional theory (DFT) was employed to study the interactions between the template and monomers to screen appropriate functional monomers for rational design of the B-DMIHM. The distinct synergic effect of GR and B-DMIHM was evidenced by the positive shift of the reduction peak potential of LMT at B-DMIHM/GR modified CPE (B-DMIHM/GR/CPE) by about 300mV, and the 13-fold amplification of the peak current, compared to a bare carbon paste electrode (CPE)...
March 30, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28372223/determination-of-vitamin-e-in-margarines-and-edible-oils-using-square-wave-anodic-stripping-voltammetry-with-a-glassy-carbon-paste-electrode
#8
Milan Sýs, Blanka Švecová, Ivan Švancara, Radovan Metelka
A new electroanalytical method for determination of vitamin E in the form of the total content of tocopherols present in margarines and edible oils has been developed. The method is based on extraction of these biologically active compounds into silicone oil, acting as lipophilic binder of glassy carbon paste electrode, with subsequent electrochemical detection by square wave anodic stripping voltammetry (SWASV) in 0.1M HNO3. The values of vitamin E contents were expressed as mass equivalent of α-tocopherol known as the most active form of this lipophilic vitamin...
August 15, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28344364/improved-electroanalytical-characteristics-for-flumetralin-determination-in-the-presence-of-surface-active-compound
#9
Dariusz Guziejewski, Sylwia Smarzewska, Radovan Metelka, Agnieszka Nosal-Wiercińska, Witold Ciesielski
ABSTRACT: The use of square wave voltammetry (SWV) and square wave adsorptive stripping voltammetry (SWAdSV) in conjunction with a cyclic renewable silver amalgam film electrode for the determination of flumetralin is presented. Poor separation of two overlapped reduction peaks is significantly improved when hexadecyltrimethylammonium bromide is used as a component of the supporting electrolyte solution (together with BR buffer pH 9.5). The SW technique parameters were investigated and found optimal as follows: frequency 50 Hz, amplitude 40 mV, and step potential 5 mV...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28342847/na-k-atpase-interaction-with-methylglyoxal-as-reactive-metabolic-side-product
#10
Marika Svrckova, Martina Zatloukalova, Petra Dvorakova, Dominika Coufalova, David Novak, Lenka Hernychova, Jan Vacek
Proteins are subject to oxidative modification and the formation of adducts with a broad spectrum of reactive species via enzymatic and non-enzymatic mechanisms. Here we report that in vitro non-enzymatic methylglyoxal (MGO) binding causes the inhibition and formation of MGO advanced glycation end-products (MAGEs) in Na(+)/K(+)-ATPase (NKA). Concretely, MGO adducts with NKA amino acid residues (mainly Arg) and N(ε)-(carboxymethyl)lysine (CML) formation were found. MGO is not only an inhibitor for solubilized NKA (IC50=91±16μM), but also for reconstituted NKA in the lipid bilayer environment, which was clearly demonstrated using a DPPC/DPPE liposome model in the presence or absence of the NKA-selective inhibitor ouabain...
March 22, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28342426/optical-and-electrochemical-dual-channel-sensing-of-cu-2-using-functionalized-furo-2-3-d-pyrimidines-2-4-1h-3h-diones
#11
Manoj Kumar, Lokesh Kumar Kumawat, Priyanka Bhatt, Anjali Jha, Shilpi Agarwal, Anuj Sharma, Vinod Kumar Gupta
Owing to their easy accessibility and high degree of structural and functional diversity, many multicomponent reactions (MCRs) have been a rich source of conjugate π-systems, functionalised chromophores (or fluorophore) and redox active molecules. Despite their high explorative potential and practical benefits, only a few MCR products have been so far investigated for their metal sensing abilities. In the present report, two furopyrimidinones (FPys) based molecular systems have been synthesized by [4+1] cycloaddition based MCR sequence...
March 18, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28319900/bipolar-electrochemiluminescence-on-thread-a-new-class-of-electroanalytical-sensors
#12
Rui Liu, Cuiling Liu, Huijie Li, Min Liu, Dan Wang, Chunsun Zhang
This paper introduces a new and simple concept for fabricating low-cost, easy-to-use capillary microchannel (CMC) assisted thread-based microfluidic analytical devices (CMCA-μTADs) for bipolar electrochemiluminescence (BP-ECL) application. The thread with patterns of carbon screen-printed electrodes and bare thread zones (BTZs) is embedded into a CMC. Such CMCA-μTADs can produce a strong and stable BP-ECL signal, and have an extremely low cost ($0.01 per device). Interestingly, the CMCA-μTADs are ultraflexible, and can be bent with a 135° bending angle at the BTZ or with a 150° bending angle at the middle of bipolar electrode (BPE), with no loss of analytical performance...
March 7, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28241117/supported-microwires-for-electroanalysis-sensitive-amperometric-detection-of-reduced-glutathione
#13
Kamonwad Ngamchuea, Chuhong Lin, Christopher Batchelor-McAuley, Richard G Compton
A carbon microfiber (7 μm diameter) is employed herein as an electroanalytical sensor. The fabricated sensor is cheap, is disposable, and requires only 150 μL of samples. The carbon fiber is surface-mounted onto an inert surface to overcome the problems of the fragility of the microwire and the possible interference of convective force due to the nonrigid nature of the wires, as well as to improve the reproducibility in length and the amperometric responses. As the cylindrical electrode is supported on a surface, the diffusion of redox-active species to the electrode is partially blocked by the substrate...
March 9, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28213250/novel-electroanalytical-method-based-on-the-electrostriction-phenomenon-and-its-application-to-determination-of-cr-vi-by-the-flow-injection-technique
#14
Marcin Wieczorek, Jolanta Kochana, Paweł Knihnicki, Karolina Wapiennik, Paweł Kościelniak
The electrostriction phenomenon is observed in membranes of thickness in the nanometer range, e.g. bilayer lipid membranes or self-assembled monolayers. Strong electrical field of 105-106V/cm in intensity appears when applying the potential lower than 1V to these membranes. Electrostatic forces change the dimensions of a dielectric, hence the membrane compression and decrease in thickness are observed. As a result, increase in the membrane capacitance is recorded. The presented work covers development and application of a new analytical method based on the innovative capacitance-to-frequency conversion method and flow technique...
May 1, 2017: Talanta
https://www.readbyqxmd.com/read/28208250/simultaneous-voltammetric-determination-of-acetaminophen-and-isoniazid-hepatotoxicity-related-drugs-utilizing-bismuth-oxide-nanorod-modified-screen-printed-electrochemical-sensing-platforms
#15
Bahaa G Mahmoud, Mohamed Khairy, Farouk A Rashwan, Craig E Banks
To overcome the recent outbreaks of hepatotoxicity-related drugs, a new analytical tool for the continuously determination of these drugs in human fluids is required. Electrochemical-based analytical methods offer an effective, rapid, and simple tool for on-site determination of various organic and inorganic species. However, the design of a sensitive, selective, stable, and reproducible sensor is still a major challenge. In the present manuscript, a facile, one-pot hydrothermal synthesis of bismuth oxide (Bi2O2...
February 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28206749/graphene-intermetallic-ptpb-nanoplates-composites-for-boosting-electrochemical-detection-of-h2o2-released-from-cells
#16
Yingjun Sun, Mingchuan Luo, Xiangxi Meng, Jing Xiang, Lei Wang, Qiushi Ren, Shaojun Guo
Rational design and construction of electrocatalytic nanomaterials is vital for improving the sensitivity and selectivity of nonenzymatic electrochemical sensors. Here, we report a novel graphene supported intermetallic PtPb nanoplates (PtPb/G) nanocomposite as an enhanced electrochemical sensing platform for high-sensitivity detection of H2O2 in neutral solution and also released from the cells. The intermetallic PtPb nanoplates are first synthesized via a simple wet-chemistry process and subsequently assembled on graphene via a solution-phase self-assembly approach...
March 21, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28192902/concentration-normalized-electroanalytical-assaying-of-exosomal-markers
#17
Qian Li, George K Tofaris, Jason J Davis
Exosomes are both active in mediating intracellular communication and potentially present a potent cargo of disease biomarkers to an assay. The robust evaluation of exosomal markers could lead to a paradigm shift in clinical analysis and associated care. To date, much of this has been hindered by issues of sample preparation and assay signal-to-noise. We introduce here the use of ultrasensitive electrochemical impedance spectroscopy to quantify both external (tetraspanin) and internal (syntenin) exosome-specific markers...
February 10, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28165236/identification-of-an-electrode-adsorbed-intermediate-in-the-catalytic-hydrogen-evolution-mechanism-of-a-cobalt-dithiolene-complex
#18
Katherine J Lee, Brian D McCarthy, Eric S Rountree, Jillian L Dempsey
Analysis of a cobalt bis(dithiolate) complex reported to mediate hydrogen evolution under electrocatalytic conditions in acetonitrile revealed that the cobalt complex transforms into an electrode-adsorbed film upon addition of acid prior to application of a potential. Subsequent application of a reducing potential to the film results in desorption of the film and regeneration of the molecular cobalt complex in solution, suggesting that the adsorbed species is an intermediate in catalytic H2 evolution. The electroanalytical techniques used to examine the pathway by which H2 is generated, as well as the methods used to probe the electrode-adsorbed species, are discussed...
February 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28157656/integration-of-gold-sputtered-electrofluidic-paper-on-wire-included-analytical-platforms-for-glucose-biosensing
#19
Estefanía Núnez-Bajo, M Carmen Blanco-López, Agustín Costa-García, M Teresa Fernández-Abedul
This work describes the fabrication and evaluation of an electroanalytical paper-based platform based on the combination of both, reusable and disposable materials in order to generate simple, versatile and low-cost microfluidic devices. With this aim, a holder containing metal wires that act as reusable reference and counter electrodes has been developed. The gold-sputtered paper electrode is disposable and easily interchangeable, meanwhile the platform that includes reference and counter electrodes can be reused...
May 15, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28107918/bismuth-nanoparticles-carbon-nanotubes-modified-sensor-for-sulfasalazine-analysis
#20
Biljana Nigović, Sandra Jurić, Iva Mitrović
Nanocomposite of bismuth nanoparticles and carbon nanotubes in Nafion matrix was used as modifier for glassy carbon electrode in analysis of anti-inflamatory drug sulfasalazine. The nanocomposite surface exhibited exceptional synergy and remarkable enhancement effect to the voltammetric response of drug. The surface morphology and structure characterization of the modified electrodes was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and cyclic voltammetry. The sensor exhibited excellent electroanalytical performance for drug determination in comparison with bismuth film electrode...
March 1, 2017: Talanta
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