Analysis of several real matrices using new mono-, bi-enzymatic, or inhibition organic phase enzyme electrodes (original) (raw)
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Organic phase enzyme electrodes: applications and theoretical studies
Analytica Chimica Acta, 2001
This short review reports the main organic phase enzyme electrodes (OPEEs) described in literature and illustrates some of the results obtained by the present authors during recent research on developing mono and bienzymatic OPEEs. Several of these are already mature biosensors (e.g. tyrosinase and catalase OPEEs and those for phosphatidylcholine and butyrylcholine determination) and applications have already been implemented, while, applications by other OPEEs are still at the experimental stage. New correlations are also illustrated between classical indicators, e.g. the log P value of several organic solvents and new empirical indicators, recently proposed by the authors, the values of which may be monitored with biosensors considered dipping directly into the organic solvent or solvent mixture.
The Enzyme Source Effect on the Performance of a Catalase Organic Phase Enzyme Electrode
Monatshefte f�r Chemie - Chemical Monthly, 2005
The role of the enzyme source was studied in the reaction of hydrogen peroxide decomposition by immobilised catalase in acetonitrile. Enzymes isolated from bacterial and mammalian sources were conveniently immobilised on a spectroscopic graphite to obtain an organic-phase enzyme electrode (OPEE). Amperometry at constant potential was employed as basic analytical approach in this study.
Organic phase enzyme electrodes
Biomolecular Engineering, 2006
In the development of biosensors, organic phase enzyme electrodes (OPEEs) have received considerable attention for the detection of substrates in organic media. This article reviews different enzymes, transductors and immobilization methods used for the preparation of OPEEs in the last decade. #
Amperometric Enzyme Electrodes
Journal of the Brazilian Chemical Society, 1997
Neste trabalho de revisão são analisados os avanços mais recentes em eletrodos enzimáticos amperométricos dando ênfase particular aos biosensores baseados na Glucose Oxidase e na Horseradish Peroxidase. A intermediação redox através de mediadores artificiais solúveis ou ligados a polímeros é discutida em termos dos desenvolvimentos teóricos recentes e verificações experimentais. É analisada a dependência da resposta amperométrica com a concentração do substrato, do mediador e da enzima assim como com o potencial do eletrodo e a espessura do filme. São também avaliadas as possíveis aplicações destes sistemas em esquemas multi-enzimáticos. Recent advances on amperometric enzyme electrodes are reviewed with particular emphasis on biosensors based on Glucose Oxidase and Horseradish Peroxidase. Redox mediation by artificial soluble and polymer attached redox mediators is discussed in terms of recent theoretical developments and experimental verification. The dependence of the amperometric response on substrate and mediator concentration, enzyme concentration, electrode potential and film thickness are analyzed. Possible applications in multienzyme schemes are also analyzed.
Inhibited enzyme electrodes. Part 1: Theoretical model
Biosensors and Bioelectronics, 1990
ABSTMCT A theoretical model is developed for an electrochemical sensor for toxic substances which works by measuring the inhibition of the enzyme activiry. The enzyme is assumed to followMichaelis44enten kinetics and the dtjusion kinetic equation describing the concentration prorle of the enzyme's substrate in the electrolyte layer between the electrode and the membrane covering the electrode is solved. A complete set of analytical solutions is found which correspond to a number of dtrerent rate limitingprocesses. Theset of solutions is described in a case diagram. The use of cytochrvme oxidase in particular is discussed.
Biosensors & Bioelectronics, 2004
A simple method of enzyme immobilization was investigated, which is useful for development of enzyme electrodes based on polyvinylferrocenium perchlorate coated Pt electrode surface. Enzymes were incorporated into the polymer matrix via ion exchange process by immersing polyvinylferrocenium perchlorate coated Pt electrode in enzyme solution for several times. Choline and acetylcholine enzyme electrodes were developed by co-immobilizing choline oxidase and acetylcholinesterase in polyvinylferrocenium perchlorate matrix coated on a Pt electrode surface. The amperometric responses of the enzyme electrodes were measured at +0.70 V versus SCE, which was due to the electrooxidation of enzymatically produced H2O2. The effects of the thickness of the polymeric film, pH, temperature, substrate and enzyme concentrations on the response of the enzyme electrode were investigated. The optimum pH was found to be pH 7.4 at 25 °C. The steady-state current of these enzyme electrodes were reproducible within ±5.0% of the relative error. Response time was found to be 30–50 s and upper limit of the linear working portions was found to be 1.2 mM choline and acetylcholine concentrations in which produced detectable currents were 1.0×10−6 M substrate concentrations. The apparent Michaelis–Menten constant and the activation energy of this immobilized enzyme system were found to be 1.74 mM acetylcholine and 14.92 kJ mol−1, respectively. The effects of interferents and stability of the enzyme electrodes were also investigated.
Analytical Characteristics of Electrochemical Biosensors
Portugaliae Electrochimica Acta, 2009
The goal of this work is the evaluation of the analytical characteristics of the determinations performed using glucose oxidase and acetylcholinesterase based electrochemical sensors, developed applying original or optimized conventional methods of enzyme immobilization. It was found that the sensitivity of glucose determination, for example, varies from 0.048 to 3.36 mA L mol -1 cm -2 and the response time of the glucose oxidase based sensors -from 5 to 30 s, according to the method of the bioreceptor immobilization. The sensitivity of the analysis is affected from the activity of the immobilized biocomponent, from the composition of the solution (concentration of the substrate, of the mediator and of the inhibitor), and from the experimental conditions (pH, temperature, agitation), as well as from the kinetic parameters of the studied process. It was found that the immobilized glucose oxidase conserves its substrate specificity in the presence of a number of glucides (galactose, maltose, fructose, and saccharose) in 100 fold higher concentrations. The selectivity of glucose analysis is ensured applying a suitable potential. Interferences free glucose amperometric determination was performed at 0.00 V/SCE, in the presence of ascorbates and urates. The electrochemical quantification of enzyme inhibitors allows reaching particularly low limits of detection (
Horseradish peroxidase-based organic-phase enzyme electrode
Analytical and Bioanalytical Chemistry, 2005
An organic-phase enzyme electrode (OPEE) based on horseradish peroxidase (HRP) immobilized within Nafion on spectroscopic graphite was investigated in acetonitrile. The amperometric electrode response to hydrogen peroxide and cumene hydroperoxide present was found to be the result of the reduction of oxygen, produced upon enzymatic decomposition of both hydroperoxides (i.e., by the catalase-like activity of HRP). The electrode response was found to depend linearly on the hydroperoxide concentration up to 700 lM within the range of potentials from À200 to À400 mV (versus Ag|AgCl). Detection limits of approximately 45 lM for H 2 O 2 and 100 lM for cumene hydroperoxide were determined under the selected experimental conditions. Nernstian dependence (the open circuit voltage of HRPbased electrode versus logarithm of H 2 O 2 concentration) was obtained between 0.2 and 2.0 mM, with a slope of approximately 23 mV per logarithmic unit, suggesting a catalase-like, two-electron disproportionation of the substrate in acetonitrile.