Amperometric Biosensor Based on Galactose Oxidase Immobilized in Clay Matrix

An amperometric galactose biosensor was developed by immobilizing galactose oxidase (GAOx) within a laponite clay film coated on a Pt electrode surface. The electrochemical assays were performed by potentiostating the GAOx/laponite bioelectrodes at +0.6 V vs. Ag/AgCl in order to oxidize the enzymatically generated hydrogen peroxide. The bioelectrochemical responses of the biosensors were optimized with regard to the buffer nature, the pH, and the GAOx/laponite ratios. Laponite provides a favorable environment to GAOx activity, since the optimized biosensor GAOx/laponite (50:25; µg:µg) shows a great sensitivity and maximum current (85 mA M−1 cm−2 and 232 µA cm−2, respectively) over a linear galactose concentration range of 1.0×10−6–1.6×10−3 M. It is also stable at least for four weeks at 4 °C.