Investigation of the optimal weight contents of reduced graphene oxide-gold nanoparticles composites and theirs application in electrochemical biosensors

Graphene, as a single-atom-thick carbon material, is considered an ideal platform for designing composite nanomaterials for high-performance electrochemical or electrocatalytic devices. Reduced graphene oxide-gold nanoparticles composites were prepared by depositing gold nanoparticles (AuNPs) on the surface of reduced graphene oxide (RGO) with different RGO-to-AuNPs weight ratios. The resulting composite materials were characterized morphologically and optically by scanning electron microscopy (SEM) and UV-visible absorption spectroscopy. Cyclic voltammetry and amperometric measurements were employed to investigate the electrocatalytic effect of different composites toward the reduction of hydrogen peroxide. Experimental results demonstrated that RGO-AuNPs composites displayed high stability and catalytic effect for the analysis of hydrogen peroxide, demonstrating the possible synergistic effects of the RGO-AuNPs composite materials. Additionally, direct electron transfer of glucose oxidase (GOD) was achieved after codeposition of GOD and chitosan (CHIT). The glassy carbon electrode modified with RGO-AuNPs/CHIT-GOD material exhibited an excellent catalytic effect for glucose detection with a sensitivity of 34 mA M^-1 cm^-2 at a detection potential of -0.3 V vs. Ag|AgCl reference.