Direct electrochemistry of glucose oxidase and sensing of glucose at a glassy carbon electrode modified with a reduced graphene oxide/fullerene-C60 composite

In the present work, a glucose biosensor was fabricated based on the direct electrochemistry of glucose oxidase at glassy carbon modified with a reduced graphene oxide (RGO) and fullerene-C60 (C60) composite. The reduced graphene oxide/fullerene (RGO-C60) composite was prepared by electrochemical reduction of a graphene oxide (GO) and C60 composite at -1.4 V for 200 s in pH 5 solution; while the GO-C60 composite was prepared by a simple sonication of C60 in GO solution for 6 hours at 45 degrees C. A well-defined and enhanced reversible redox peak of GOx was observed at RGO-C60 composite compared with other modified electrodes. The heterogeneous electron transfer rate constant (K-s) and the surface coverage concentration of GOx at RGO-C60/GOx modified electrode were calculated to be 2.92 s(-1) and 1.19 x 10(-10) mol cm(-2), respectively. Under optimum conditions, the amperometry response of the biosensor was linear against the concentration of glucose from 0.1 to 12.5 mM with a response time of 3 s. The limit of detection was estimated to be 35 mM based on S/N = 3 with a high sensitivity of 55.97 mA mM(-1) cm(-2). In addition, the fabricated biosensor showed a good practical ability for the detection of glucose in human blood serum samples.