Self-wiring from tyrosinase to an electrode with redox polymers

Wiring from tyrosinase to an electrode with redox polymers was conducted by tyrosinase itself. Tyrosinase was immobilized on an indium tin oxide (ITO) electrode, and was further modified with melanin synthesized by tyrosinase from l-tyrosine (self-wiring). The thus-prepared tyrosinase–melanine electrode responded amperometrically to oxygen at −0.5 V vs. SCE. A tyrosinase-modified electrode was also modified with another quinone-based redox polymer synthesized from phenol and a diamine by self-wiring and/or electrochemical polymerization (electrochemical wiring) at the ITO surface. When the tyrosinase was wired successively by electrochemical polymerization and self-wiring, the electrode (EW–SW electrode) exhibited the highest response. Although both the self-wired and electrochemically wired tyrosinase electrodes respond to oxygen, the activity for phenol oxidation of the self-wired electrode was much smaller than that of the electrochemically wired electrode. This suggests a successful connection of the polymer to the tyrosinase active center in the self-wired electrode. The EW–SW electrode was further modified with glucose oxidase, and responded to 0.1–10 mM glucose.