Enzyme Cascade for Catalyzing Sucrose Oxidation in a Biofuel Cell

Biofuel cells provide a safe and renewable means of powering small electronic devices. We have recently demonstrated a bioanode that is capable of extracting four electrons from a single molecule of sucrose by way of a three-enzyme cascade.  Invertase, fructose dehydrogenase and glucose oxidase are immobilized in a ferrocene-modified linear poly(ethylenimine) (LPEI) hydrogel onto the surface of a carbon electrode.  Fuel sources are generated in the polymer film by (1) hydrolyzing sucrose into fructose and glucose, and then (2) electroenzymatically oxidizing fructose and glucose to produce a current response.  A previously unreported synergistic effect is observed between glucose oxidase and fructose dehydrogenase that results in a current response that is considerably higher than expected.  The newly described enzyme cascade generated 302 ± 57 μA/cm² at 25 ^oC and 602 ± 62 μA/cm² at 37 ^oC and when poised against an air breathing platinum cathode in a biofuel cell, the multienzyme-containing film generated 42 ± 15 μW/cm² at 172 mV with a maximum current density of 344 ± 25 μA/cm² in 100 mmol/L sucrose at 25 ^oC.