Studies in applied bioelectrochemistry

Thesis

This thesis descibes the development of bioelectrochemical systems for application as biomedical analytical devices and fuel cells based on biological catalysts.

A range of ferrocene derivatives in the oxidised, ferricinium ion, form act as electron acceptors for the enzyme glucose oxidase. Kinetic information for these reactions was obtained by using the electrochemical technique of D. C. cyclic voltammetry. An amperometric enzyme electrode for the detection of glucose was devised based upon 1,1'-dimethylferrocene. The enzyme electrode was constructed using graphite foil as the base sensor on to which the ferrocene was doped and glucose oxidase covalently immobilised. In gravimetrically prepared buffered solutions of glucose the electrode gave a current proportional to the bulk glucose concentration in the range l-30mM, which encompasses the range over which a diabetic's body glucose may vary. The electrode response is independent of pH, has a temperature coefficient of ca. 4%/°C and is insensitive to many potentially interfering substances found in biological samples. The electrode was used to assay both plasma and whole-blood samples from diabetics.

The enzyme electrode was also used to monitor changes in glucose concentration. An electrochemical assay was devised involving a coupled sequence of enzymes which consume glucose at a rate determined by the activity of the enzyme creatine kinase. This assay for creatine kinase may be useful in the diagnosis of acute myocardial infarction.

The ferricinium ion was studied as a general electron acceptor for oxido-reductases and a range of electrochemically coupled enzymatic oxidation reaction devised. These systems form the basis for the development of amperometric enzyme electrodes for detecting pyruvate, lactate, alcohols, sarcosine, xanthine, aldehydes, isocitrate, NADH, NADPH and carbon monoxide.

An alternative use for an amperometric enzyme electrode is as an anodic half-cell of a fuel cell. A biofuel cell based upon the oxidation of methanol by the quinoprotein alcohol dehydrogenase was developed.

Authors: Davis, G

• Publication date: 1984
• DOI: 10.5287/ora-rvzqmmd7b
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Subjects: Enzymes; Bioelectrochemistry; Ferrocene