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Title: Developing applications of bioelectrochemistry : interfaces and electrocatalytic synthesis
Author: Weeks, Justin R.
ISNI:       0000 0004 8507 9730
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2020
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The use of biomolecules in chemical applications, such as biosensors, fuel cells and chemical synthesis, is becoming widespread, as improvements are made in biomolecule production, engineering and stability, and cofactor provision. This allows chemists to exploit the selectivity and high activities often observed with biological molecules such as antibodies and enzymes. This thesis concerns the characterisation of (i) an alkanethiol monolayer interface for the immobilisation of antibodies for biosensing, and (ii) the development of an electrochemical cofactor regeneration system for an application in bioelectrosynthesis. Firstly, experiments are performed to confirm the capacitance characteristics of alkanethiol films on gold surfaces. These films have been used as antibody supports for promixal biosensing of antigens, though most examples have required the use of a redox transducer to measure an electrochemical signal. A more specific model for the capacitance of a molecular film has been developed and the empirical observation of these parameters is confirmed in this thesis. Secondly, an electrochemically-driven NADH regeneration system is presented with NAD⁺-reductase modified carbon electrodes, offering perfect selectivity for the active NADH cofactor. It is shown that the NAD⁺-reductase enzyme can be immobilised onto carbon interfaces and that it is electrochemically active at much more modest potentials than using unmodified electrodes. NADH-dependent oxidoreductase enzymes offer exquisite selectivity under mild reaction conditions, but have proved difficult to exploit in electrosynthesis. These enzymes require stoichiometric hydride transfer from the expensive biological NAD(P)H cofactor, which means that their use is only viable when they are coupled with an efficient cofactor recycling method. This bioelectroenzymatic system is demonstrated as a modular approach to biocatalytic reductions, coupling NADH-dependent reductases for efficient C=X reductions. Application of this bioelectrocatalytic interface to an electrochemical flow cell increases catalytic activity, with turnover frequencies up to 8.19s⁻¹, improves stability and allows for in line optimisation analysis.
Supervisor: Vincent, Kylie Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Chemistry ; Inorganic Chemistry ; Bioinorganic chemistry