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 (H2BpybcBr2) 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 H2BpybcBr2/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 μmol L−1 to 1.30 mmol L−1 and a detection limit of 51 μmol L−1. The apparent Michaelis–Menten constant (Km) 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 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.

Graphical abstractThis study demonstrated the physico-chemical adsorption of the viologen mediator to the surface of nanocrystalline TiO2 film. In this approach, the organic compound acts as a molecular wire to link the enzyme and the oxide surface.Figure optionsDownload full-size imageDownload high-quality image (55 K)Download as PowerPoint slide