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Electrochemical immoblisation of enzymes on microelectrodes

Electrochemical immoblisation of enzymes on microelectrodes
Electrochemical immoblisation of enzymes on microelectrodes

The immobilisation of enzymes on microelectrodes is important for the fabrication of in vivo biosensors. In this thesis electropolymerised films of poly(phenol) have been used to immobilise glucose oxidase and flavocytochrome b2 to make a 25 μm diameter platinum disc microelectrodes responsive to glucose and lactate respectively. The fabrication of enzyme electrodes in this manner is simple, reproducible and exhibit fast response times. The stability of the enzyme microelectrodes generally reflected the stability of the enzyme in solution. The poly(phenol) was found to be very suitable to reduce the interference currents from ascorbic acid, uric acid and acetamidophenol. A theoretical model for this enzyme microelectrode is also presented.

The electrochemical studies on poly(phenol) showed that the growth solution pH affects the oxidation potential of growth. In situ studies by neutron reflection have provided density profiles perpendicular to the electrode surface. The thickness of poly(phenol) films grown in the absence of enzyme by potential step from 0 to + 0.9 V vs SCE, was found to be 100 AA. Ellipsometric studies agreed well with the neutron reflection data, and showed that there was no difference between poly(phenol) grown on glassy carbon or platinum electrodes. Furthermore when the poly(phenol) films were grown by cyclic voltammetry there appeared to be two phases of growth: only one was observed when growth was carried out by potential step. A protein binding experiment using fluorescent labelled concanavalin A (which binds specifically to mannose) showed that it does bind to poly(phenol) films containing glucose oxidase but not to poly(phenol) alone, which suggests that the enzyme is not totally buried within the poly(phenol) film.

Three methods have been used to attach mediator molecules to the enzyme protein structure.

University of Southampton
Caruana, Daren Joseph
Caruana, Daren Joseph

Caruana, Daren Joseph (1994) Electrochemical immoblisation of enzymes on microelectrodes. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The immobilisation of enzymes on microelectrodes is important for the fabrication of in vivo biosensors. In this thesis electropolymerised films of poly(phenol) have been used to immobilise glucose oxidase and flavocytochrome b2 to make a 25 μm diameter platinum disc microelectrodes responsive to glucose and lactate respectively. The fabrication of enzyme electrodes in this manner is simple, reproducible and exhibit fast response times. The stability of the enzyme microelectrodes generally reflected the stability of the enzyme in solution. The poly(phenol) was found to be very suitable to reduce the interference currents from ascorbic acid, uric acid and acetamidophenol. A theoretical model for this enzyme microelectrode is also presented.

The electrochemical studies on poly(phenol) showed that the growth solution pH affects the oxidation potential of growth. In situ studies by neutron reflection have provided density profiles perpendicular to the electrode surface. The thickness of poly(phenol) films grown in the absence of enzyme by potential step from 0 to + 0.9 V vs SCE, was found to be 100 AA. Ellipsometric studies agreed well with the neutron reflection data, and showed that there was no difference between poly(phenol) grown on glassy carbon or platinum electrodes. Furthermore when the poly(phenol) films were grown by cyclic voltammetry there appeared to be two phases of growth: only one was observed when growth was carried out by potential step. A protein binding experiment using fluorescent labelled concanavalin A (which binds specifically to mannose) showed that it does bind to poly(phenol) films containing glucose oxidase but not to poly(phenol) alone, which suggests that the enzyme is not totally buried within the poly(phenol) film.

Three methods have been used to attach mediator molecules to the enzyme protein structure.

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More information

Published date: 1994

Identifiers

Local EPrints ID: 462806
URI: http://eprints.soton.ac.uk/id/eprint/462806
PURE UUID: f78b1726-1479-4761-ac9f-284dfae2b3f4

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Date deposited: 04 Jul 2022 20:05
Last modified: 04 Jul 2022 20:05

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Author: Daren Joseph Caruana

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