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.