PORTUGALIAE ELECTROCHIMICA ACTA Analytical Characteristics of Electrochemical Biosensors (original) (raw)
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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 (
Electrochemical Evaluation of the Properties of the Immobilized Enzyme Glucose Oxidase
ECS Transactions, 2008
The enzyme glucose oxidase was evaluated as a recognition element in electrochemical biosensors. Immobilization techniques as physical adsorption, entrapment in electrogenerated polymer film, affinity and covalent binding are discussed based in the involved physicochemical and kinetic phenomena. This includes the determination of the main kinetic parameters: apparent Michaelis-Menten constant K m app and maximal rate I max of the heterogeneous enzyme reactions of glucose oxidation in the absence and in the presence of inhibitors. Parameters as pH, optimal temperature and stability of the biocatalyst were established analyzing the transfer function of the developed amperometric glucose oxidase sensors of first and second generation I=I max [S] / (K m app + [S]).
Sensors and Actuators B: Chemical, 1996
The feasibility of an amperometric glucose biosensor based on immobilization of glucose oxidase (GOD) in inorganic gels (laponite) is investigated. The gels modified with enzyme were deposited onto platinum electrodes and then were exposed to glutaraldehyde vapor. The effects of different parameters (glutaraldehyde crosslinking and time of drying) on the performances of the biosensor have been studied. For optimum conditions, remarkably good characteristics were obtained: larger dynamic range (0.1--4 mM of glucose), higher/max, higher sensitivity (threefold better than this obtained through immobilization of enzymes in laponite films). The main advantage of the biosensor reported here is its long stability. The biosensor was kept for several weeks in a buffer solution at 4°C. About 450 measurements were done without any loss of the linearity in the range (0.1-4 mM). The possibility of an increase in the amount of enzyme in the biofilm which has been demonstrated, allows us to obtain more sensitive devices. geywords: Biosensor; Glucose oxidase; Inorganic gels; Laponite; High sensitivity; Long term stability 0925-4005/96/$15.00
TALANTA, 2005
Electrochemical glucose enzyme biosensors have been prepared on carbon film electrodes made from carbon film electrical resistors. Evaluation and characterisation of these electrodes in phosphate buffer saline solution has been carried out with and without pretreatment by cycling in perchloric acid or at fixed applied potential. Both pretreatments led to a reduction in the carbon surface oxidation peak and enabled better detection of hydrogen peroxide in the pH range of 5-7. Glucose oxidase enzyme was immobilised on the carbon surface by mixing with glutaraldehyde, bovine serum albumin and with and without Nafion. The performance of these two types of electrode was similar, that containing Nafion being more physically robust. Linear ranges were up to around 1.5 mM, with detection limits 60 M, and pretreatment of the carbon film electrode at a fixed potential of +0.9 V versus SCE for 5 min was found to be the most beneficial. Michaelis-Menten constants between 5 mM and 10 mM were found under the different experimental conditions. Coating the immobilised enzyme layer with a thin layer of Nafion was found to give similar results in the determination of glucose to mixing it but with benefits against interferences for the analysis of complex matrices, such as wine. Potentialities, for a short-term-use or disposable sensors, are indicated.
Journal of the Chilean Chemical Society
In this study, an electrochemical biosensor was developed by using a sol-gel coating solution. The modified platinum electrode used in the study was constructed by immobilization of glucose oxidase under a layer of sol-gel film. The sol-gel coating solution was prepared by using GLYMO, TEOS, and MTEOS. Electrochemical measurements were carried out amperometrically by determining hydrogen peroxide produced by the enzymatic reaction between glucose and glucose oxidase. The amperometric responses of the resulting enzymatic electrode to glucose were rapid. It was observed that the amperometric response of the enzymatic electrode was linear for glucose concentrations in the range from 2 to18 mM with 50 s response time. LOD and LOQ for the enzymatic electrode were calculated to be 0.055 mM and 0.184 mM, respectively. It was determined that the developed biosensor had an acceptable reproducibility. The selectivity of the biosensor was determined in the presence of some interfering substanc...
formerly Philippine Agriculturist, 2007
(English) Amperometric biosensors for bonded glucose were fabricated using screen printed carbon elecrode bulk modified with manganese dioxide onto which glucosidase and glucose oxidase were immobilized by Nafion film entrapment. Three methods of enzyme immobilization were performed (layering, mixing and sequencing of enzyme solutions). The analytical performance of the biosensor prepared by different enzyme immobilization methods was assessed in a flow injection mode using three sugar ...
Biosensors for determination of glucose with glucose oxidase immobilized on an eggshell membrane
Talanta, 2004
A glucose biosensor using an enzyme-immobilized eggshell membrane and oxygen electrode for glucose determination has been fabricated. Glucose oxidase was covalently immobilized on an eggshell membrane with glutaraldehyde as a cross-linking agent. The glucose biosensor was fabricated by positioning the enzyme-immobilized eggshell membrane on the surface of a dissolved oxygen sensor. The detection scheme was based on the depletion of dissolved oxygen content upon exposure to glucose solution and the decrease in the oxygen level was monitored and related to the glucose concentration. The effect of glutaraldehyde concentration, pH, phosphate buffer concentration and temperature on the response of the glucose biosensor has been studied in detail. Common matrix interferents such as ethanol, d-fructose, citric acid, sodium benzoate, sucrose and l-ascorbic acid did not give significant interference. The resulting sensor exhibited a fast response (100 s), high sensitivity (8.3409 mg L −1 oxygen depletion/mmol L −1 glucose) and good storage stability (85.2% of its initial sensitivity after 4 months). The linear response is 1.0 × 10 −5 to 1.3 × 10 −3 mol L −1 glucose. The glucose content in real samples such as commercial glucose injection preparations and wines was determined, and the results were comparable to the values obtained from a commercial glucose assay kit based on a spectrophotometric method.
Development of a novel enzyme based glucose sensor
Progress in Biotechnology, 1995
Glucose oxidase from Aspergillus niger is an extremely stable, FAD-dependent enzyme that has found wide application in electrochemical sensing of glucose in blood. Conventional sensor technology immobilises this enzyme in membranes deposited on top of the transducer. Here we report a new containment technology where the glucose oxidase is immobilised in gelatine or polyvinylalcohole and is deposited in the chip in pyramidal containments produced on silicon by anisotropic etching. This configuration of the sensor enhances the adhesion and stability of the membrane and has been applied to monitoring glucose in serum discontinuously as well as continuously in a flow-through system. Moreover we demonstrate the applicability of the containment technology to monitor glucose ex vivo with the help of a rnicrodialysis system.