INVESTIGATION OF VIOLOGEN DERIVATIVES AS ELECTRON-TRANSFER MEDIATORS IN AMPEROMETRIC GLUCOSE SENSORS

Using experiments involving cyclic voltammetry and stationary potential measurements, it was shown that several water-soluble viologens, N,N'-di(4-nitrobenzyl)viologen dichloride, poly(o-xylylviologen dibromide) and poly(p-xylylviologen dibromide), can efficiently mediate electron transfer from reduced glucose oxidase to a conventional carbon paste electrode. Whereas most viologens cannot serve as electron-transfer mediators for flavoenzymes owing to their highly negative redox potentials, these molecules have sufficiently anodic redox potentials (more positive than that of flavin adenine dinucleotide) that they can reoxidize reduced glucose oxidase. These redox potentials are, however, sufficiently cathodic that glucose sensors based on glucose oxidase and these mediators can be operated in a potential range where the oxidation of common interfering species, such as ascorbic acid and uric acid, does not occur.