Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized on L-glutathione self-assembled monolayers

A novel hydrogen peroxide biosensor has been fabricated based on covalently linked horseradish peroxidase (HRP) onto L-glutathione self-assembled monolayers (SAMs). The SAMs-based electrode was characterized by electrochemical methods, and direct electrochemistry of HRP can be achieved with formal potential of -0.242 V ( vs. saturated Ag/AgCl) in pH 7 phosphate buffer solution (PBS), the redox peak current is linear to scan rate and rate constant can be calculated to be 0.042 s(-1). The HRP-SAMs-based biosensors show its better electrocatalysis to hydrogen peroxide in the concentration range of 1 x 10(-6) mol/L to 1.2 x 10(-3) mol/L with a detection limit of 4 x 10(-7) mol/L. The apparent Michealis-Menten constant is 3.12 mmol/L. The biosensor can effectively eliminate the interferences of dopamine, ascorbic acid, uric acid, catechol and p-acetaminophen. (C) 2008 Ji Ming Hu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.