Linear dependence of the potential of "wired" glucose oxidase electrodes on the concentration of glucose

Potentiometric assays, unlike amperometric or coulometric ones, do not requ ire accurate definition and knowledge of the area of the measuring electrod e or microcell volume. Their potential scales, however, with the logarithm of the concentration of the analyte, while in amperometric, chronoamperomet ric, or chronocoulometric assays the charge or current scales linearly with the concentration. Here we show that in a potentiometric glucose assay the potential can scale linearly with concentration. Such scaling is realized when the electrode is coated with a resistive, but nevertheless electron-co nducting, film where glucose is electrooxidized. The film consists of a red ox polymer film that "wires" reaction centers of covalently coimmobilized g lucose oxidase to the electrode. After a potential pulse is applied to the "wired" enzyme electrode so that the electrode-bound redox centers are elec trooxidized, the floating electrode potential decays to a value that varies linearly with the concentration of glucose.