An outstandingly sensitive enzyme-free glucose sensor prepared by co-deposition of nano-sized cupric oxide and multi-walled carbon nanotubes on glassy carbon electrode

An amperometric glucose sensor with excellent sensitivity, very low detection limit and low glucose oxidation potential was prepared by casting of suspension of copper oxide (CuO) nanoparticles/multi-walled carbon nanotubes (MWCNTs) on the surface of a glassy carbon electrode (GCE). Dimethyl formamide (DMF)/H2O (9:1) was used as a new suspending media. Electrochemical activity of the electrode toward the oxidation of glucose was studied using differential pulse voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy. A synergistic effect was substantiated between the MWCNTs and nano-CuO for glucose electroxidation. The effects of nanocomposite layer thickness and MWCNTs/CuO mass ratio on the sensor performance were investigated and optimized. The detection limit, and linear range of the sensor were identified as 0.07 (+/- 0.03) mu mol L-1 (S/N =3) and 0.5-2000.0 mu mol L-1, respectively, under applied oxidation potential of 0.35 V (vs. Ag/AgCl). The sensor exhibited excellent sensitivity of 3968.42 (+/- 0.84) mu A L mmol(-1) cm(-2) to glucose, being higher than those of the previously reported similar sensors. The determination of glucose (5.0 mu mol L-1, n = 5) with the sensor resulted in RSD% of 3.4. Furthermore, the reproducibility of the sensor was equal to 5.7%. The developed sensor was compared with other enzyme-less glucose sensors and its superiority over them was demonstrated reasonably. The optimized sensor was applied to glucose determination in blood samples. The efficiency of the sensor for glucose determination was comparable with that of a commercial enzymatic sensor. (C) 2015 Elsevier B.V. All rights reserved.