A Nafion-free non-enzymatic amperometric glucose sensor based on copper oxide nanoparticles–graphene nanocomposite

• A stable Nafion-free nanoCuO/graphene coated GC electrode was introduced.
• The importance of solvent used for the casting of graphene/CuO was demonstrated.
• A synergistic electrocatalytic effect was found between graphene and nanoCuO.
• High sensitivity of 2939.24 μA mM−1 cm−2 was obtained for enzyme-free glucose sensor.
• Determination range of 0.5–2000 μM and detection limit of 0.09 μM were obtained.

A new and simple method was introduced for the preparation of a non-enzymatic amperometric glucose sensor based on CuO nanoparticles–graphene nanocomposite. Differential pulse voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy were used for the evaluation of the prepared sensors. The synthesized graphene and CuO nanoparticles were dispersed in DMF/H2O (90:10) solvent mixture and then a little amount of the suspension was drop-coated on the surface of a glassy carbon electrode. It was found that the kind of solvent, utilized for the dispersion of graphene and CuO nanoparticles, had very crucial effect on both sensitivity and reproducibility of the prepared sensor. The nanocomposite coating thickness and CuO/graphene mass ratio were optimized to achieve the best sensitivity. A synergistic effect was substantiated between graphene and CuO nanoparticles for electro-catalytic oxidation of glucose. Dependence of the sensor response to glucose concentration was dynamically linear between 0.5 and 2000 μmol L−1 and at this concentration range the optimized sensor represented very high sensitivity (2939.24 μA mM−1 cm−2). Moreover, the detection limit of 0.09 μmol L−1 was calculated for this sensor. The sensor was properly utilized for glucose assay in blood samples.

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