A non-enzymatic amperometric sensor for glucose based on cobalt oxide nanoparticles

Abstract

A cobalt oxide nanoparticle-modified glassy carbon (CONM/GC) electrode was prepared by potential cycling in a pH-controlled solution containing tartrate. The electrocatalytic oxidation of glucose on CONM/GC electrode in alkaline solution was investigated and the kinetics was developed. In cyclic voltammograms, the peak current of the oxidation of low valence cobalt oxide in the presence of glucose is increased and it was followed by a decrease in the corresponding cathodic current. This suggested that glucose oxidation was being catalysed on the redox mediator with an electrocatalytic mechanism. Using cyclic voltammetry, chronoamperometry, steady-state polarisation measurements and impedance spectroscopy, the kinetic parameters of the glucose electrooxidation such as charge-transfer coefficient, the catalytic reaction rate constant and the diffusion coefficient were determined. Based on the results, an efficient enzyme-less sensing procedure for determination of glucose was developed. The resulting sensor exhibited excellent performance for the glucose determination and a sensitive and time-saving amperometric procedure was successfully applied for the quantification of glucose in both batch and flow systems. Glucose was determined with a linear range of 0.7–60 µM, a limit of detection of 0.15 µM and a sensitivity of 2515.35 µA mM−1 cm−2 in batch system and with a linear range of 1.3–50 µM, a limit of detection of 0.14 µM and a sensitivity of 3240.25 µA mM−1 cm−2 in the flow system.