Fabrication of AucoreCo3O4shell/PAA/HRP Composite Film for Direct Electrochemistry and Hydrogen Peroxide Sensor Applications

Abstract

A completely new biosensor composed of cube-shaped Au core Co 3 O 4shell nanoparticles (Au core Co 3 O 4shell ), polyacrylic acid (PAA), and horseradish peroxidase (HRP) modifi ed fi lm electrode was fabricated for the fi rst time. The biocompatibility and electrochemical properties of the resulting Au core Co 3 O 4shell -PAA-HRP composite film were studied by electrochemical impedance spectroscopy, UV-visible spectroscopy, and cyclic voltammetry. The UV-vis spectrum obtained suggests that HRP retains its native conformation in the modifi ed fi lm. The immobilized HRP shows a pair of quasireversible redox peaks at −0.31 V in 20 mM PBS (pH 7.0), and the biosensor shows a fast amperometric response to hydrogen peroxide with a linear range of 2.0×10 −6 to 3.7×10 −4 M. The kinetic parameters such as k s (electron transfer rate constant) and K M (Michaelis-Menten constant) are evaluated to be about 7.4 s −1 and 0.91 mM, respectively. These indicate that the cube-shaped Au core Co 3 O 4shell nanoparticles are an ideal candidate material for direct electrochemistry of redox proteins and for the construction of related enzyme biosensors, and that they may fi nd potential applications to biomedical, food, and environmental analyses and detection.