Copper(ii) doped nanoporous TiO2 composite based glucose biosensor

Abstract

In this report we simply prepared a copper(II) doped nanoporous TiO2 composite, which combines the capabilities of an immobilizing enzyme with electrocatalyzing glucose. Transmission electron microscopy and energy dispersive X-ray analysis were used for the characterization of the composite. Comparison experiments of the cyclic voltammetry and electrochemical impedance spectroscopy of Cu(II) doped TiO2 composites with different doping ratio modified electrodes demonstrate that when the ratio of Cu(II) and TiO2 is kept at 1 : 1, the electrochemical response to glucose is the best. We suggest that in the doping materials too little TiO2 would decrease the immobilization of GOx, which leads to a poorer response to glucose. However, too little Cu(II), would decrease the electron transfer ability. Cu(II) doped TiO2 with the ratio of 1 : 1 displays a good linear relation between the oxidation peak current and the concentration of glucose with the range from 0.5 μM–3 mM, correlation coefficients of 0.9989 and a fast response time of within 5 s. The experimental limit of detection, based on a signal-to-noise ratio of 3, was 0.1 μM and the sensitivity of the sensor was 0.9040 μA μM−1. The experimental results also showed that the sensor has good reproducibility, long-term stability and is interference free.