A New Catechol Biosensor Immobilized Polyphenol Oxidase by Combining Electropolymerization and Cross-Linking Process

Abstract

A highly stable and effective catechol biosensor was prepared by immobilizing polyphenol oxidase (PPO) into polyaniline (PANI) film by using the direct electropolymerization (one-step) process in conjunction with cross-linking with glutaraldehyde. The results of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirmed that the immobilization of PPO was successful. The biosensor has a fast response to catechol (10 s) with a linear range of 1.0–100 µM and a detection limit of 0.01 µM. The maximum response current (I max) and the Michaelis-Menten constant (k' m) were found to be 7.94 µA and 81.32 µM, respectively. The activation energy (E a) of the PPO catalytic reaction was 16.5 kJ/mol. The biosensor exhibited good stability by retaining 80% of its original activity when stored in a dry state at 4°C for up to 5 months.