Osmium-based redox polymer mediated glucose oxidase electrodes were characterized in the absence and presence of O2 for use as anodes in glucose/O2 based biofuel cells. In N2 saturated conditions, glucose oxidation current density of up to 2 mA/cm2 was observed whereas significant loss in current was noticed in the presence of O2 saturated conditions.Mediating performance of the synthesized redox polymers with respect to GOx and effect of oxygen in the system was quantitatively studied in terms of mediator redox potential, osmium loading and diffusivities. A one-dimensional model of a redox polymer-mediated, enzyme electrode was developed in order to account for the presence of oxygen. Kinetic parameters were determined by fitting to the experimental current density measurements for varying potential, glucose and O2 concentrations. Kinetic parameters specific to the mediator reaction were an order of magnitude higher than other homogeneous mediated systems ascribed to better mediation efficiency of the synthesized redox polymers. Bimolecular rate constants for GOx-O2 reaction were found to be an order of magnitude lower than that of the free solution, which can be attributed to the reduced activity of immobilized GOx. Performance of the system was analyzed via simulation under various conditions.
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