One-step synthesis of poly(thionine)-Au nano-network and nanowires and its application for non-enzyme biosensing of hydrogen peroxide

We describe the preparation of novel poly(thionine)-Au materials, where the poly(thionine)-Au nano-network and nanowires have been synthesized in aqueous solution via the polymerization of thionine using HAuCl₄ as the oxidant in a single reaction setup. The synthesis process does not require templates, nor does it require large amounts of organic solvents or electrochemical methods. The morphology of the nanocomposites can be controlled by varying the thionine/HAuCl₄ ratio. The resulting poly(thionine)-Au network was used to fabricate a novel non-enzyme hydrogen peroxide (H₂O₂) biosensor. In pH 7.0 phosphate buffer, almost interference-free determination of H₂O₂ was realized at ? 0.1 V versus Ag/AgCl with a linear of 1 × 10^? 4 to 5 × 10^? 2 M, a correlation coefficient of 0.998 and a response time of < 2 s. The developed biosensor showed a detection limit of 0.2 μM (S/N = 3) with very good stability, reproducibility and high selectivity.