Two-Stage Oxidation of Glucose by an Enzymatic Bioanode

The present study reports the design of a novel bioanode to deeply oxidize glucose in an enzymatic biofuel cell (EFC). This enzymatic glucose cell utilizes three co-immobilized enzymes: NAD-dependent glucose dehydrogenase (GDH), NAD(P)(+)-dependent gluconate-5-dehydrogenase (Ga5DH), and diaphorase (DI). Glucose is oxidized to gluconate by NAD-dependent GDH, gaining two electrons per glucose; the gluconate obtained as a by-product is oxidized at the C5 carbon to 5-keto-gluconate by Ga5DH. Operation of our bioanode enabled the oxidation of glucose in two stages, resulting in the gain of four electrons. The three-enzyme EFC provides a maximum power density of 10.51 +/- 1.72Wcm(-2), which is about 1.6 times higher than the maximum power density of an EFC using a bioanode based on the co-immobilization of two enzymes (GDH and DI). Our results hold promise for increasing the current density of EFCs, and for application in glucose biosensor.