Analytical Sciences

Novel Hydrogen Peroxide Sensors Based on Peroxidase-Carrying Poly{pyrrole-co-[4-(3-pyrrolyl)butanesulfonate]} Copolymer Films

Saipin THANACHASAI, Shunsaku ROKUTANZONO, Shoichiro YOSHIDA, and Tadashi WATANABE

Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan

Amperometric hydrogen peroxide biosensors were fabricated by incorporating horseradish peroxidase (HRP) into poly{pyrrole-co-[4-(3-pyrrolyl)butanesulfonate]} (Py-PS) copolymer films deposited on an SnO₂ electrode surface by electropolymerization. The HRP/Py-PS electrodes exhibited an extended dynamic range and a markedly improved operational and storage stability, compared with HRP-incorporated polypyrrole (PPy) electrodes prepared under similar conditions. The linear range was expanded from 10^-7 - 10^-4 M to 10^-7 - 10^-3 M H₂O₂. In about 80 measurements over three weeks, the HRP/Py-PS electrode retained 60% of its initial response, while the HRP/PPy electrode almost completely lost activity. The influence of the electrodeposition solution pH on the sensor response was also investigated. Our results suggest that an expansion of the linear range and an enhancement of lifetime are due to electrostatic interactions of HRP with a negatively-charged Py-PS copolymer.

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