NADH oxidation using modified electrodes based on lactate and glucose dehydrogenase entrapped between an electrocatalyst film and redox catalyst-modified polymers

Electrocatalytic NADH oxidation was investigated at an electrode architecture involving an electropolymerized layer of poly(methylene blue) (pMB) or poly(methylene green) (pMG) in combination with specifically designed toluidine blue or nile blue modified methacrylate-based electrodeposition polymers. Either NAD(+)-dependent lactate dehydrogenase or NAD(+)-dependent glucose dehydrogenase were entrapped between the primary electropolymerized layer of pMB or pMG and the methacrylate-based redox polymer. The composition of the polymer backbone and the polymer-bound redox dye was evaluated and it could be demonstrated that the combination of the electropolymerized pMB or pMG layer together with the dye modified methacrylate-based redox polymer shows superior properties as compared with either of the components alone. NADH was oxidized at an applied potential of 0 mV vs Ag/AgCl/KCl 3 M and current densities of 17 mu A center dot cm(-2) and 28 mu A center dot cm(-2) were obtained for modified electrodes based on lactate dehydrogenase and glucose dehydrogenase, respectively, at substrate saturation.