AN ENZYMATIC GLUCOSE BIOSENSOR BASED ON THE CODEPOSITION OF RHODIUM, IRIDIUM, AND GLUCOSE OXIDASE ONTO A GLASSY CARBON TRANSDUCER

The performance of a first-generation glucose biosensor based on the entrapment of glucose oxidase (GOx) within a net of iridium and rhodium codeposited onto activated glassy carbon electrode, is described. The presence of rhodium in the plating solution allows the deposition of iridium and GOx under conditions at which this is not possible without rhodium. The electrocatalytic activity of the bioelectrode containing both metals towards the oxidation and reduction of hydrogen peroxide improves drastically compared to those of the bioelectrodes containing GOx and iridium or rhodium. The sensitivity for glucose obtained with Ir-RhGOx/GCE is almost seven times higher than that obtained for Rh-GOx/GCE and by far higher than that for Ir-GOx/GCE which under the working conditions is almost zero. The influence of the electrodeposition conditions on the response of the bioelectrode was evaluated from the amperometric signals of hydrogen peroxide and glucose. At 0.0 V the response to glucose is linear up to 1.0 × 10-2 M. At -0.050 V, no interference occurs neither for ascorbic acid nor for uric acid even at concentrations higher than the maximum physiological levels.