Graphene Oxide Directed One-Step Synthesis of Flowerlike Graphene@HKUST-1 for Enzyme-Free Detection of Hydrogen Peroxide in Biological Samples

A novel metal-organic framework (MOF)-based electroactive nanocomposite containing graphene fragments and HKUST-1 was synthesized via a facile one-step solvothermal method using graphene oxide (GO), benzene-1,3,5-tricarboxylic acid (BTC), and copper nitrate (Cu(NO3)2) as the raw materials. The morphology and structure characterization revealed that the GO could induce the transformation of HKUST-1 from octahedral structure to the hierarchical flower shape as an effective structure-directing agent. Also, it is interesting to find out that the GO was torn into small fragments to participate in the formation of HKUST-1 and then transformed into the reduction form during the solvothermal reaction process, which dramatically increased the surface area, electronic conductivity, and redox-activity of the material. Electrochemical assays showed that the synergy of graphene and HKUST-1 in the nanocomposite leaded to high electrocatalysis, fast response, and excellent selectivity toward the reduction of hydrogen peroxide (H2O2). Based on these remarkable advantages, satisfactory results were obtained when the nanocomposite was used as a sensing material for electrochemical determination of H2O2 in the complex biological samples such as human serum and living Raw 264.7 cell fluids.