An H₂O₂ Biosensor Based on Immobilization of Horseradish Peroxidase Labeled Nano‐Au in Silica Sol‐Gel/Alginate Composite Film

Abstract

A novel approach to assemble an H₂O₂ amperometric biosensor was introduced. The biosensor was constructed by entrapping horseradish peroxidase (HRP) labeled nano‐scaled particulate gold (nano‐Au) (HRP‐nano‐Au electrostatic composite) in a new silica sol‐gel/alginate hybrid film using glassy carbon electrode as based electrode. This suggested strategy fully merged the merits of sol‐gel derived inorganic‐organic composite film and the nano‐Au intermediator. The silica sol‐gel/alginate hybrid material can improve the properties of conventional sol‐gel material and effectively prevent cracking of film. The entrapment of HRP in the form of HRP‐nano‐Au can not only factually prevent the leaking of enzyme out of the film but also provide a favorable microenvironment for HRP. With hydroquinone as an electron mediator, the proposed HRP electrode exhibited good catalytic activity for the reduction of H₂O₂. The parameters affecting both the qualities of sol‐gel/alginate hybrid film and the biosensor response were optimized. The biosensor exhibited high sensitivity of 0.40 Al mol⁻¹ cm⁻² for H₂O₂ over a wide linear range of concentration from 1.22×10⁻⁵ to 1.46×10⁻³ mol L⁻¹, rapid response of <5 s and a detection limit of 0.61×10⁻⁶ mol L⁻¹. The enzyme electrode has remarkable stability and retained 86% of its initial activity after 45 days of storage in 0.1 mol L⁻¹ Tris‐HCl buffer solutions at pH 7.

Keywords:

• Amperometric biosensor
• silica sol‐gel/alginate composite material
• HRP‐nano‐Au, hydrogen peroxide

Acknowledgments

The authors thank the Scientific Research Fund of Hunan Provincial Education Department (04C160) and Hunan Provincial Natural Science Foundation of China (04JJ40017) for financial support.