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.