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Title: Development of disposable amperometric glucose biosensors
Author: Lau, King Tong.
ISNI:       0000 0001 3605 5220
Awarding Body: Birkbeck (University of London)
Current Institution: Birkbeck (University of London)
Date of Award: 2002
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This thesis describes the development of three integrated solid-state electrochemical (amperometric) sensors for glucose measurement in a disposable format. This work envisages a sensor that measures glucose in biological samples e.g. whole blood. All three sensors were constructed based on using the enzyme glucose oxidase as the analyte-selective agent, which was immobilized on carbon electrode by physically entrapped in a PVA-Nafion™ polymer composite membrane. The first sensor system (described in Chapter 3) uses insoluble ammonium salts of hexacyanoferrate as a mediator for measuring hydrogen peroxide (in cathodic mode, working at ea -400mV vs. Ag-AgCI» produced from the reaction between glucose and glucose oxidase. Hydrogen peroxide sensing with these waterinsoluble ferricyanide modified electrodes were first studied. Tetrahexyl ammonium ferricyanide (THAF) was used as the model compound to investigate glucose sensing. The glucose sensors functioned well in static solution. For flow analysis, the sensors were found to perform better when operating in anodic mode at ca 200mV vs. Ag-AgCI, where the ferricyanide worked as a mediator for GOx. Chapter 4 describes the investigation of a second mediator system, the waterinsoluble benzoquinone derivatives. These mediators have lower reduction potential than benzoquinone and minimise the effects of common interferents in biological samples. 2,6-dimethylbenzoquinone based glucose sensors operate at potentials around 200mV vs. Ag-AgCI. Common interferents at biological concentrations did not cause any problems for the optimised sensor that used a Nafion™ membrane to exclude anionic species. However, an approach that used a comparator sensor to compensate for interference has been developed. Chapter 5 reports the synthesis and investigation of a novel mediator Nmethylphenazinium iron tetrachloride (NMPITC). It was found that the compound was able to oxidise reduced GOX and reduced hydrogen peroxide at different potentials. The performance as electron mediator for GOX in solution and in solidstate sensor was investigated. The sensor constructed with this mediator operated at low potentials (ca lOOmV vs. Ag-AgCl) that minimized the effects of common interferents.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available