Chemical modification of a nanocrystalline TiO2 film for efficient electric connection of glucose oxidase

A novel biosensor for glucose was prepared by adsorption of 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridinium di-bromide compound (H(2)BpybcBr(2)) onto the surface of a nanocrystalline TiO2 film deposited onto FTO glasses, which was used as a platform to assemble the enzyme glucose oxidase to the electrode surface. The H(2)BpybcBr(2)/TiO2/FTO modified electrode was characterized by scanning electron microscopy, X-ray fluorescence image, cyclic voltammograms and spectroelectrochemical measurements. The immobilization of GOD on functionalized TiO2 film led to stable amperometric biosensing for glucose with a linear range from 153 mu mol L-1 to 1.30 mmol L-1 and a detection limit of 51 mu mol 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 mu A mmol L-1. The study proved that the combination of viologen mediators with TiO2 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. (C) 2010 Elsevier Inc. All rights reserved.