Fabrication of gold nanoparticles on bilayer graphene for glucose electrochemical biosensing

The hydrophilic and carboxyl group functionalized graphene-gold nanoparticles (AuNPs) hybrid has been synthesized in situ. AuNPs can be scattered well on the graphene bilayer, and the loading amount of AuNPs can be controlled. Glucose oxidase (GOD) was successfully bound to the surface of the hybrid through a condensation reaction between terminal amino groups on the lysine residues of GOD and carboxyl groups on the AuNPs. The hybrid provided a suitable microenvironment for GOD to retain its biological activity. The direct and reversible electron transfer process between GOD and the hybrid electrode was realized without any supporting film or electron mediator. A novel model of the glucose biosensor based on the hybrid electrode was fabricated. Blood sugar concentrations measured in human serum samples by the glucose biosensor were in good agreement with the values provided by the Nanjing University hospital, and the average relative standard deviation was 3.2% for six successive measurements. Three constructed biosensors showed good stability, and all of them retained 80% of their initial signals after they were stored at 4 degrees C for four months. It is promising that the model of the glucose biosensor can be used as an effective candidate for the detection of blood sugar concentration in clinical diagnoses.