Amperometric Biosensor for Polyphenol Based on Horseradish Peroxidase Immobilized on Gold Electrodes

Abstract

Horseradish peroxidase (HRP) is covalently immobilized on a self-assembled monolayer of mercaptopropionic acid on vapor-deposited gold electrode. The electrode allows the polyphenol detection down to 2 µM with a linear relationship up to 25 µM. The reduction current of oxidized polyphenols, formed during the enzymatic oxidation of polyphenolic compounds in the presence of H2O2, is proportional to their concentration. The sensitivity of the detection of various polyphenols by the present method depends on both the electron-donating properties of polyphenols and the electron-accepting properties of oxidized polyphenols. The total amounts of polyphenols in several wine and tea samples detected by the present method are well correlated with those determined by the Folin-Ciocalteu method. In addition, this method has several advantages over the Folin-Ciocalteu method: shorter detection time, smaller sample volume, and more torelant to interference substances.