Electrocatalysis of Horseradish Peroxidase Immobilized on Cobalt Nanoparticles Modified ITO Electrode

Abstract

It is the first time that Horseradish peroxidase (HRP) was successively immobilized on the magnetic cobalt nanoparticles modified ITO (indium tin oxide) electrode. Morphologies of electrode surface were featured by the field emission‐scanning electron microscope (FSEM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the modified process of electrode. Direct electrochemistry and electrocatalysis of HRP immobilized on nano‐Co/ITO were investigated. The biosensor exhibited high sensitivity, good stability, and excellent electrocatalytic activity to the reduction of H₂O₂. Under the optimized experimental conditions, a calibration curve over 2.0×10⁻⁹∼2.0×10⁻⁸ mol l⁻¹ and 2.0×10⁻⁷∼2.0×10⁻⁶ mol l⁻¹, with a limit of detection of 1.9×10⁻⁹ mol l⁻¹ was obtained. The apparent Michaelis‐Menten constant (K _M ^app ) for HRP/nano‐Co/ITO electrode was calculated to be 0.79 mmol l⁻¹, indicating a higher affinity of HRP attached on the modified electrode.

Keywords:

• Indium tin oxide (ITO)
• Horseradish peroxidase (HRP)
• cobalt nanoparticles
• electrocatalysis

The National Natural Science Foundation of China (Nos. 20275007) is gratefully acknowledged.