A Glucose Biosensor Based on Immobilization of Glucose Oxidase into 3D Macroporous TiO2

3D macroporous TiO2 inverse opals have been derived from a sol-gel procedure using polystyrene colloidal crystals as templates. EDS and SEM showed a face-centered cubic (FCC) structure TiO2 inverse opal was obtained. Glucose oxidase (GOx) was successfully immobilized on the surface of indium-tin oxide (ITO) electrode modified by TiO2 inverse opal (TiO2(IO)). Electrochemical properties of GOx/TiO2(IO)/ITO electrode were characterized by using the three electrodes system. The result of cyclic voltammetry showed that a couple of stable and well-defined redox peaks for the direct electron transfer of GOx in absence of glucose, and the redox peak height enhanced in presence of 0.1 mu M glucose. Compare with the ordinary structured GOx/TiO2/ITO electrode, inverse opal structured GOx/TiO2(IO)/ITO electrode has a better respond to the glucose concentration change. Under optimized experimental conditions of solution pH 6.8 and detection potential at 0.30 V versus saturated calomel electrode (SCE), amperometric measurements were performed. The sensitivity and the detection limit of glucose detection was 151 mu A cm(-2) mM(-1) and 0.02 mu M at a signal-to-noise ratio of 3, respectively. The good response was due to the good biocompatibility of TiO2 and the large effective surface of the three-dimensionally ordered macroporous structure.