Sandwich-Type Amperometric Enzyme Electrodes for Determination of Glucose (original) (raw)
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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.
Enzyme electrode for glucose determination in whole blood
Talanta, 1997
The development of a glucose sensor suitable for use with whole blood is described. It is based on anodic oxidation at +700 mV of hydrogen peroxide with a platinum electrode covered with a gas permeable membrane. Glucose reacts with glucose oxidase immobilised on the external side of the membrane, and forms hydrogen peroxide which is able to cross the gas permeable membrane due to its high vapour tension, while other electroactive substances that are important interferents are completely blocked. This principle was discovered several years ago but no practical application was presented up to now. Therefore in this work a number of different commercial membranes were tested, in order to obtain a resistant, rapidly responding and interference free sensor to be used in conjunction with a blood gas measurement apparatus. Coimmobilisation of glucose oxidase and catalase was found to be useful for fast response and recovery of the electrode. Using some of the tested membranes, the lineari...
Mathematical modelling of amperometric enzyme electrodes with perforated membranes
Biosensors and Bioelectronics, 1993
A mathematical model of a modified amperometric enzyme electrode based on a multilayer enzyme membrane has been investigated. The model describes different facilities to extend the linear ~on~entmtion range of multilayer membrane electrodes as compared to an enzyme sensor with a normal sandwich membrane. This is exemplified by various experimental results.
Analytical Chemistry, 1986
A new liquid membrane electrode based on an Ion assoclatlon extraction system responding to ephedrlne Is described. It incorporates an ephedrlne-flavianate ion palr complex as a novel electroactive component in 1-octanol. The electrode exhibits near-Nernstian response over the concentration range of lo-* to M ephedrlne In soiutlons of pH 4-7. The electrode also responds to some neurotransmitters contalnlng the 6-ethanolamine moiety. Response tlme varies from 20 to 90 s, and interferences from many organic bases and some
Biosensors and Bioelectronics, 2004
Glucose oxidase (GOD) was immobilized on screen-printed platinum electrodes by entrapment in a screen printable paste polymerized by irradiation with UV-light. The influences of different additives, in particular polymers and graphite, on the sensitivity and stability of the sensor and the permeability of the enzyme layer for a possible electrochemical interferent were investigated. The chosen additives were Gafquat 755N, poly-l-lysine, bovine serum albumin (BSA), sodium dodecylsulfate (SDS), polyethylene glycol (PEG), Nafion and graphite. All additives led to increases of glucose signals, i.e. improved the sensitivity of glucose detection with Gafquat 755N, poly-l-lysine, SDS and graphite showing the strongest influences with increases by a factor 4, 6.5, 5 and 10, respectively. Ascorbic acid was used as a model interferent showing the influence of the enzyme layer composition on the selectivity of the sensor. The addition of Gafquat 755N or poly-l-lysine led to higher signals not only for glucose, but also for ascorbic acid. SDS addition already reduced the influence of ascorbic acid, which was almost completely eliminated when Nafion (5%) and PEG (10%) were added. A comparable beneficial effect on the selectivity of the sensors was also observed for the addition of 0.5% graphite. Thus, the enzyme electrodes with PEG, Nafion or graphite as additives in the enzyme layer were applied to glucose determinations in food samples and samples obtained from E. coli cultivations. the co-factor flavin-adenine dinucleotide (FAD) is reduced to FADH 2 , followed by the re-oxidation of the co-factor by molecular oxygen producing hydrogen peroxide while glucono-␦-lactone is hydrolysed in aqueous media to gluconic acid according to the following three reaction steps:
Covalently immobilized enzymes on biocompatible polymers for amperometric sensor applications
Biosensors and Bioelectronics, 1996
Glucose oxidase or choline oxidase were covalently immobilized on the surface of 2-hydroxyethyi and glycidyl methacrylate copolymer membranes. The polymerization was induced by gamma irradiation at low temperature. The enzyme modified polymers were applied on Clark-type or platinum electrodes to form amperometric sensors based on the electrochemical measurements of oxygen or hydrogen peroxide. Glucose and choline content in standard solutions were measured and linear calibration curves were determined. The sensors studied showed a response time of less than 2 min and the observed linear ranges were increased with respect to usual biosensors owing to the diffusion-limiting effects of the membranes used. The influence of the copolymer composition on the electrochemical response and on the retained enzyme activity were explored for verifying the optimum analytical performance. The immobilized enzyme membranes stored in suitable buffers were very stable and showed a decrease up to 20% in the electrode response after 3 months of constant use.
Enzyme electrode formed by evaporative concentration and its performance characterization
Biosensors and Bioelectronics, 2007
A highly concentrated immobilized enzyme layer was formed on a small working electrode, and the behavior of the electrode as an amperometric sensor was examined. To this end, a super-hydrophobic layer was formed in an area other than the sensitive area by using polytetrafluoroethylene (PTFE) beads. A small droplet of an enzyme solution containing glucose oxidase (GOD) and bovine serum albumin (BSA) was placed on the sensitive area, concentrated by evaporation, and crosslinked with glutaraldehyde. With the same enzyme activity per unit area, the current density increased with smaller working electrodes. Also, the current density increased with higher enzyme loadings up to a limiting value. In addition, the linear range of the calibration plot was expanded to higher glucose concentrations. The enzyme electrode fabricated by the novel method was incorporated in a micro-flow channel. Compared with large enzyme electrodes with the same enzyme activity per unit area, smaller electrodes showed a significant increase in the current density and a decrease in the flow dependence. The conversion efficiency could be improved by narrowing the flow channel and increasing the number of electrodes, which was comparable with a large electrode placed in a shallow flow channel.
Electrosynthesis of a new enzyme-modified electrode for the amperometric detection of glucose
Journal of Electroanalytical Chemistry, 2000
The electrooxidation of a new aminonaphthalene compound modified with a carboxylic acid function, 1-(5-aminonaphthyl)ethanoic acid (ANEA) was studied, with a view to binding glucose oxidase (GOD) covalently. Its electrooxidation leads to thin films (PANEA) on bare glassy carbon (GC) platinum (Pt) electrodes and also on prepolymerized aminonaphthoquinone (PANQ) films. Polymer-modified bilayer electrodes Pt/PANQ/PANEA were then constructed. GOD was covalently bound onto these electrodes, leading to a Pt/PANQ/PANEA/GOD glucose sensor. The amperometric response to glucose was monitored in aerated and deaerated conditions. The results show very efficient covalent binding of GOD and good enzyme activity on the electrode surface.