Chemical modification of a nanocrystalline TiO 2 film for efficient electric connection of glucose oxidase

Abstract

A novel biosensor for glucose was prepared by adsorption of 1,1′-bis(4-carboxybenzyl)-4,4′-bipyridinium di-bromide compound (H 2BpybcBr 2) onto the surface of a nanocrystalline TiO 2 film deposited onto FTO glasses, which was used as a platform to assemble the enzyme glucose oxidase to the electrode surface. The H 2BpybcBr 2/TiO 2/FTO modified electrode was characterized by scanning electron microscopy, X-ray fluorescence image, cyclic voltammograms and spectroelectrochemical measurements. The immobilization of GOD on functionalized TiO 2 film led to stable amperometric biosensing for glucose with a linear range from 153 μmol L −1 to 1.30 mmol L −1 and a detection limit of 51 μmol L −1. The apparent Michaelis–Menten constant ( K m ) was estimated to be 3.76 mmol L −1, which suggested a high enzyme-substrate affinity. The maximum electrode sensitivity was 1.25 μA mmol L −1. The study proved that the combination of viologen mediators with TiO 2 film retains the electrocatalytic activity of the enzyme, and also enhances the electron transfer process, and hence regenerating the enzyme in the reaction with glucose.