WIRED ENZYME ELECTRODES FOR AMPEROMETRIC DETERMINATION OF GLUCOSE OR LACTATE IN THE PRESENCE OF INTERFERING SUBSTANCES

Glucose oxidase (GOX) or lactate oxidase (LOX) were immobilized in an osmium-based three-dimensional redox hydrogel that electrically connec ted the enzyme's redox centers to electrodes. The enzyme ''wiring'' hy drogel was formed by cross-linking poly(1-vinylimidazole) (PVI) comple xed with Os-(4,4'-dimethylbpy)(2)Cl (termed PVI15-dmeOs) with poly(eth ylene glycol) diglycidyl ether (peg). Glucose and lactate sensors exhi bited typical limiting current densities of 250 and 500 mu A/cm(2), re spectively. When the electrodes were poised at 200 mV (SCE), the curre nts resulting from electrooxidation of ascorbate, urate, acetaminophen , and L-cysteine were negligible. When a Nafion film was employed, the linear range was extended from 6 to 30 mM glucose and from 4 to 7 mM lactate. The redox potential of the gel-forming polymer was 95 mV (SCE ). Glucose and lactate measurements performed in bovine calf serum cor related well with a substrate calibration in phosphate buffer.