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 entrap ment of glucose oxidase (GOx) within a net of iridium and rhodium codeposit ed onto activated glassy carbon electrode, is described. The presence of rh odium in the plating solution allows the deposition of iridium and GOx unde r conditions at which this is not possible without rhodium. The electrocata lytic activity of the bioelectrode containing both metals towards the oxida tion and reduction of hydrogen peroxide improves drastically compared to th ose of the bioelectrodes containing GOx and iridium or rhodium. The sensiti vity for glucose obtained with Ir-Rh-GOx/GCE is almost seven times higher t han 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 el ectrodeposition conditions on the response of the bioelectrode was evaluate d from the amperometric signals of hydrogen peroxide and glucose. At 0.0 V the response to glucose is linear up to 1.0 x 10(-2) M. At -0.050 V. no int erference occurs neither for ascorbic acid nor for uric acid even at concen trations higher than the maximum physiological levels.