The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Joseph Wang - One of the best experts on this subject based on the ideXlab platform.
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thermally stable improved first generation glucose biosensors based on nafion glucose oxidase modified heated electrodes
Electrochemistry Communications, 2009Co-Authors: Tafeng Tseng, Yangli Yang, Minchieh Chuang, Gerd-uwe Flechsig, Michal Galik, Joseph WangAbstract:We illustrate how the use of heated electrodes enhances the performance of glucose biosensors based on Amperometric detection of the glucose-oxidase generated hydrogen peroxide. Nafion is shown to be an excellent matrix to protect glucose-oxidase from thermal inactivation during the heating pulses. The influence of the electrode temperature upon the Amperometric response is examined. Temperature pulse amperometry (TPA) has been used to obtain convenient peak-shaped analytical signals. Surprisingly, up to 67.5 °C, the activity of Nafion-entrapped glucose-oxidase is greatly enhanced (24-fold) by accelerated kinetics rather than decreased by thermal inactivation. Amperometric signals even at elevated temperatures are stable upon prolonged operation involving repetitive measurements. The linear calibration range is significantly extended.
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electrochemistry of nicotinamide adenine dinucleotide reduced at heated platinum electrodes
Analytica Chimica Acta, 2005Co-Authors: Carolin Lau, Gerd-uwe Flechsig, Peter Grundler, Joseph WangAbstract:This paper reports on the electrochemical behavior and determination of nicotinamide adenine dinucleotide reduced (NADH) at indirectly electrically heated platinum electrodes. At room temperature, a surface fouling can be observed during voltammetric and Amperometric measurements, whereas a slight electrode heating during the measurements greatly minimizes such electrode passivation. This is illustrated by repetitive cyclic and square-wave voltammetric scans as well as using amperometry. The effect of electrode temperature and NADH concentration is evaluated. Amperometric calibration data exhibit a 10-fold higher sensitivity upon elevating the electrode temperature from 22 to 75 °C. Furthermore, the Amperometric response at the hot Pt-electrode is very stable, with 86% of the initial activity remaining after 20 min stirring of 5 mM NADH (compared to 32% under cold conditions). This represents the first example of using heated electrodes for minimizing surface fouling effects. The ability of heated Pt-electrodes to promote the NADH electron-transfer reaction suggests great promise for dehydrogenase-based Amperometric biosensors.
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Amperometric BIOSENSORS IN REVERSED MICELLES
Journal of Electroanalytical Chemistry, 1994Co-Authors: A.j. Reviejo, F. Liu, José M. Pingarrón, Joseph WangAbstract:The possibilities and advantages of using reversed micelles as appropriate working media for the development of Amperometric enzyme biosensors with analytical purposes is discussed. The influence of the composition of reversed micelles on the Amperometric responses obtained at the enzyme electrodes is illustrated. Some analytical applications such as the determination of phenolic pollutants, of the antioxidant BHA and of dimethyl- and diethyldithiocarbamates are shown.
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Selectivity coefficients for Amperometric sensors.
Talanta, 1994Co-Authors: Joseph WangAbstract:Abstract Selectivity coefficients (k amp ij ) are introduced as well-defined measures of the selectivity of Amperometric sensors. For any Amperometric device the total current response in the presence of interfering species (j) can be described by the general equation; i t = K (C i + Σk amp ij C j ), where i is the target analyte. Equations are derived for k amp ij under different conditions common in Amperometric sensing. Factors influencing the selectivity coefficients of Amperometric probes, including the recognition and transduction mechanisms, the controlled-potential operating technique, and the transducer geometry are discussed. The selectivity coefficient strategy is illustrated experimentally with two widely used applications of Amperometric devices, the anodic monitoring of dopamine at Nafion-coated electrodes and the biosensing of glucose at glucose-oxidase enzyme probes. It is anticipated that the selectivity coefficient strategy will become widespread in Amperometric devices, and for chemical sensors in general, and will not be limited only to potentiometric probes.
Elena E Karyakina - One of the best experts on this subject based on the ideXlab platform.
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prussian blue based first generation biosensor a sensitive Amperometric electrode for glucose
Analytical Chemistry, 1995Co-Authors: Arkady A Karyakin, Olga V Gitelmacher, Elena E KaryakinaAbstract:A first-generation Amperometric glucose biosensor based on a Prussian Blue-modified electrode was developed. Prussian Blue was found to be a better electrocatalyst for hydrogen peroxide reduction than platinum. H 2 O 2 was detected at the Prussian Blue-modified electrode in the presence of oxygen by both electrooxidation and electroreduction. The glucose Amperometric biosensor was made by glucose oxidase immobilization onto a Prussian Blue-modified electrode with a Nafion layer. The biosensor response exhibited a linear dependence on analyte concentration in the range 1 x 10 -6 -5 x 10 -3 M. The cathodic current density after addition of 10 -6 M glucose was 0.18 μA/ cm 2 . When hydrogen peroxide produced via the enzyme reaction was detected by electroreduction, the biosensor response was independent of reductants. This Amperometric biosensor is expected to obey the requirements for noninvasive diagnostics.
Arkady A Karyakin - One of the best experts on this subject based on the ideXlab platform.
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prussian blue based first generation biosensor a sensitive Amperometric electrode for glucose
Analytical Chemistry, 1995Co-Authors: Arkady A Karyakin, Olga V Gitelmacher, Elena E KaryakinaAbstract:A first-generation Amperometric glucose biosensor based on a Prussian Blue-modified electrode was developed. Prussian Blue was found to be a better electrocatalyst for hydrogen peroxide reduction than platinum. H 2 O 2 was detected at the Prussian Blue-modified electrode in the presence of oxygen by both electrooxidation and electroreduction. The glucose Amperometric biosensor was made by glucose oxidase immobilization onto a Prussian Blue-modified electrode with a Nafion layer. The biosensor response exhibited a linear dependence on analyte concentration in the range 1 x 10 -6 -5 x 10 -3 M. The cathodic current density after addition of 10 -6 M glucose was 0.18 μA/ cm 2 . When hydrogen peroxide produced via the enzyme reaction was detected by electroreduction, the biosensor response was independent of reductants. This Amperometric biosensor is expected to obey the requirements for noninvasive diagnostics.
Jui-hsiang Hsieh - One of the best experts on this subject based on the ideXlab platform.
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Effects of Tin Oxide Sputtered on a Carbon Electrode for Fabricating Glucose Biosensor
Journal of The Electrochemical Society, 2008Co-Authors: Cheng-wei Liao, Jung-chuan Chou, Shen-kan Hsiung, Jui-hsiang HsiehAbstract:Tin oxide (SnO 2 ) thin films are sputtered onto a commercial carbon electrode to develop a SnO 2 electrode. A mediator (ferrocene-carboxylic acid) and an enzyme (glucose oxidase) are coimmobilized by polyvinylalcohol bearing styrylpyridinium groups on the surface of the carbon and SnO 2 electrodes, to fabricate carbon and SnO 2 Amperometric glucose biosensors. Following electrode modification, the applied potential is reduced from 452 to 236 mV and the current response increases from 320 to 508 μA cm -2 as the carbon and SnO 2 Amperometric glucose biosensors are immersed in 360 mg/dL glucose solution. The detection limit of the carbon Amperometric glucose biosensor is 360 mg/dL under an applied potential of 452 mV. Furthermore, when the applied potential is set to 236 mV, the detection limit of the SnO 2 Amperometric glucose biosensor reaches 600 mg/dL. No significant interference is observed when the applied potential is set at 236 mV. Furthermore, the glucose concentration determined by the glucose presence in the serum sample agrees closely with that in the buffer solution. The merits of reducing the applied potential and increasing current response enable a highly accurate SnO 2 Amperometric glucose biosensor based on a low-cost substrate to be developed in this study.
Mohammad Ghadermarzi - One of the best experts on this subject based on the ideXlab platform.
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Amperometric detection of nitrite iodate and periodate at glassy carbon electrode modified with catalase and multi wall carbon nanotubes
Sensors and Actuators B-chemical, 2007Co-Authors: Abdollah Salimi, Abdollah Noorbakhsh, Mohammad GhadermarziAbstract:Abstract The electrocatalytic reduction of nitrite, iodate and periodate has been studied at catalase-incorporated multi-wall carbon nanotubes (MWCNTs) supported on a glassy carbon electrode. Cyclic voltammograms of the catalase-incorporated MWCNTs indicate a pair of well defined and nearly reversible redox couple. The embedded catalase in the MWCNTs films show excellent electrocatalytic activity toward iodate, nitrite and periodate reduction in acidic solutions at unusually positive potentials. Furthermore, catalase-modified MWCNTs supported on a glassy carbon rotating disk electrode shows good analytical performance for Amperometric determination of selected anions. Under optimized condition of the amperometry method the concentration calibration range, detection limit and sensitivity are 1 μM to 6 mM, 0.15 μM and 55.6 nA/μM for periodate, 1 μM to 5 mM, 0.2 μM and 44.4 nA/μM for iodate and 5 μM to 10 mM, 1.35 μM and 7 nA/μM for nitrite, respectively. Meanwhile, the catalase activity in the carbon nanotubes films is significantly enhanced with apparent Michaelis–Menten constants of 0.9, 1.41 and 1.14 mM for iodate, periodate and nitrite, respectively. Excellent electrochemical reversibility of the redox couple, good reproducibility, high stability, low detection limit, long term life, fast amerometric response (within 5 s), wide linear range, technical simplicity and possibility of preparation at a short period of time are great advantages of this sensor. The obtained results show potential and promising practical application for the catalase-MWCNTs-modified electrode in Amperometric sensor for oxoanions determination. This sensor can be used as an Amperometric detector for analysis of nitrite, iodate and periodate in chromatographic or flow systems.