Electrochemistry and application of a novel monosubstituted squarate electron-transfer mediator in a glucose oxidase-doped poly(phenol) sensor
E. I. Iwuoha, A. R. Williams-Dottin, L. A. Hall, A. Morrin, G. N. Mathebe, M. R. Smyth, and A. Killard
Department of Chemistry, University of the Western
Cape, Belleville 7535, South Africa; Department of Chemistry, The University
of the West Indies, St.Augustine, Trinidad; School of Chemical Sciences,
Dublin City University, Dublin 9, Ireland
Abstract: Electrosynthetic poly(phenol) nanofilms were deposited
in situ on platinum electrodes in the presence and absence of glucose
oxidase. The synthesis charges and currents of the nonconducting polymer
films were recorded at various applied potentials for films grown from
25 100 mM phenol concentrations. Film parameters such as the standard
rate constant for film deposition, film thickness, and surface concentration
of the poly(phenol) films were evaluated from the cyclic and step voltammograms
of the polymerization process. A novel electron-transfer mediator consisting
of monosubstituted 4-hydroxycyclobut-3-ene-1,2-dione (squarate) was
used as a mediator for Pt/poly(phenol) nanofilm/GOx amperometric glucose
biosensors. Amperometric responses for 3-diphenylamino-4-hydroxycyclobut-3-ene-1,2-dione
(diphenylaminosquarate: E°'=of +328 mV/Ag-AgCl at pH 7.0)-mediated
systems were measured by both steady-state amperometric and cyclic voltammetry.
The sensor sensitivity was calculated to be 558 nA cm2 (µM)1.
*Plenary lectures presented at the Inaugural Conference for the Southern and Eastern Africa Network of Analytical Chemists (SEANAC), Gaborone, Botswana, 7-10 July 2003. Other presentations are published in this issue, pp. 697-888.
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