Highly Selective First Generation Glucose Biosensor Based on Carbon Paste Containing Copper and Glucose Oxidase

Abstract

A highly selective electrochemical glucose biosensor based on the dispersion of copper microparticles and glucose oxidase into a carbon paste matrix is described. Copper offers a very efficient and preferential electrocatalytic activity towards the reduction of enzymatically generated hydrogen peroxide. Careful evaluation of the influence of copper content in the paste on the sensitivity and selectivity of the biosensor was performed, and 1.2 % w/w copper was selected as the optimum. Hence, the strong electrocatalytic effect of copper towards hydrogen peroxide allows for a fast and remarkably selective glucose quantification at −0.100 V. No interference was observed even in the presence of large excess of ascorbic acid (up to 3.5×10−3 M), uric acid (up to 5.0×10−4 M, 8.3 mg %) or acetaminophen (up to 7.4×10−4 M). The detection limit was 150 μM, and the response was linear up to 6.0×10−3 M. When stored dried at 4 °C, the sensor showed almost no change in the analytical performance after operating for 30 days. Calibration plots performed with glucose solutions prepared in human blood serum samples containing undetectable glucose level, showed no appreciable differences with those obtained using pure glucose standard solutions. The usefulness of the bioelectrode for direct glucose quantification in human blood serum matrices is also discussed.