Development of Amperometric Hydrogen Peroxide Sensor Based on Horseradish Peroxidase-Immobilized Poly(Thiophene-co-EpoxyThiophene)

A modified electrode for hydrogen peroxide (H₂O₂) sensing was prepared via thiophene (Th) with epoxy group. Thiophene (EpoxyTh) with epoxy group was synthesized by reaction of 3-bromothiophene and glycidyl methacrylate (GMA) in acetonitrile according to Heck Reaction. The electrocopolymerization of Th and EpoxyTh was performed on the surface of indium tin oxide (ITO) electrode by cycling the potential between -1.0 and +2.5 V in mixture of thiophene (Th) and EpoxyTh. Poly(Th-co- EpoxyTh) grown onto the ITO electrode was successfully confirmed by SEM, AFM, and water contact angle analysis, respectively. Finally, the HRP was immobilized on the surface of poly(Th-co-EpoxyTh) electrode by covalent binding. The amperometric response of the HRP-immobilized poly(Th-co-EpoxyTh) electrode for H₂O₂ was examined by cyclic voltammetry (CV). The HRP-immobilized poly(Th-co-EpoxyTh) electrode showed linearity from 0.1 to 30 mM H₂O₂, good reproducibility, and long life time.