A very thin overoxidized polypyrrole membrane as coating for fast time response and selective H2O2 amperometric sensor

Pyrrole electrooxidation in the presence of weak-acidic anions allows one to locally, rapidly and in single step form on the electrode a pinhole-free very thin layer of overoxidized polypyrrole (OPPy). This membrane could be really useful for the design of amperometric biosensor based on oxidation of H2O2 generated by an oxidase. Indeed, using rotation disk electrode, the apparent diffusion coefficient of H2O2 within this OPPy film was found to be 10−8 cm2 s−1, which corresponds to a fast response time of 0.1 ms. Moreover, it is shown that with this system, platinum electrode coated with the very thin OPPy membrane, the H2O2 sensitivity is excellent (700 nA μM−1 cm−2) and the H2O2 selectivity relative to potentially interfering species present in biological fluids, such as ascorbate and dopamine, is very good. Thus, this OPPy membrane which can be locally electrodeposited is ideal for the construction of oxidase-based microbiosensors.