Enzymatic biofuel cell on flexible nanoporous gold electrodes

A glucose/O₂-based biofuel cell employing nanoporous gold electrodes (NPG) supported by Kapton® was prepared. The anode was prepared by drop-casting a solution of Crassicarpon hotsonii cellobiose dehydrogenase (ChCDH) and an Os complex-based polymer and the cathodes by covalent immobilization of Magnaporthe oryzae bilirubin oxidase (MoBOD) on 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM). Both electrodes were coated with poly(2-methacryloyloxyethyl phosphorylcholine-co-glycidyl methacrylate) (MPC) to reduce biofouling. The anode had a J_max of 172 ± 10 μA cm⁻² and a K_Mapp of 19 ± 3 mM in phosphate buffer saline, with a linear detection range from 1 to 5 mM and a sensitivity of 9.4 ± 0.3 μA cm⁻² mM⁻¹. In artificial plasma, the response was saturated at 3 mM, with J_max of 6.8 ± 10 μA cm⁻², K_Mapp of 1 mM and a linear detection range from 1 to 5 mM. The cathode had a J_max of 103 μA cm² and retained 80 % of its response after 18 h of continuous measurement in phosphate buffered saline, while in artificial plasma, the stability was significantly reduced with a half-life of 1 h under continuous operation. The power outputs in PBS and artificial serum were 4.4 and 1.0 μWcm⁻², respectively.