Transparent and Capacitive Bioanode Based on Specifically Engineered Glucose Oxidase

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Here we detail an optimized transparent capacitive glucose oxidizing bioanode, capable of supplying current densities of 10 µA cm−2 at applied potentials of 0.1 V–0.2 V versus saturated calomel electrode, when continuously performing in a simple phosphate buffer, pH 7.4 and artificial human tears, both with a glucose concentration of 0.05 mM only. When operating in pulse mode, the bioanode was able to deliver current densities as high as 21 µA cm−2 at the beginning of the pulse with 571 µC cm−2 total charges stored. The biogenic part of the enzymatic device was a recombinant glucose oxidase mutant from Penicillium amagasakiense with high catalytic efficiency towards glucose, up to 14.5⋅104 M−1 s−1. The non‐biogenic part of the anodic system was based on a poly(3,4‐ethylenedioxythiophene)‐graphene nanocomposite, as a highly capacitive component with a capacitance density in the 1 mF cm−2 range, multi‐walled carbon nanotubes, as an additional nanostructuring element, and a conductive organic complex, as an electron shuttle between the redox enzyme and the electrode surface. The bioanode could potentially serve as a prototype of a double‐function enzymatic anode for hybrid electric power biodevices, energizing smart contact lenses.