Nitrogen doped reduced graphene oxide (N-RGO) was successfully prepared by carbon thermal reduction method, which annealed graphene oxide (GO) and cyanamide at 900℃. The 0.2% acetic acid solution with chitosan (CS) was used as the dispersant of N-RGO to improve the dispersivity, electronic mass transfer rate, and biocompatibility of N-RGO. The morphology, structure and electrochemical properties of N-RGO and CS/N-RGO were investigated by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), and cyclic voltammetry (CV). FT-IR spectrum indicated graphene oxide (GO) was reduced and N-RGO was successfully prepared. The electrochemical experiments demonstrated that CS/N-RGO possesses large electrochemical effective area, strong adsorptive ability and fast electronic mass transfer rate. Then a novel electrochemical sensor for detection of xanthine was fabricated based on CS/N-RGO modified glassy carbon electrode (CS/N-RGO/GCE). It exhibited good electrochemical response toward the oxidation of xanthine with a linear range covering 2.99×10^-8~1.07×10^-4 mol/L, and the corresponding detection limit (LOD) of 9.96×10^-9 mol/L (S/N=3). In addition, the electrochemical behaviors of xanthine on CS/N-RGO/GCE were explored using cyclic voltammetry (CV), which included the pH effect on the oxidation of xanthine and the effect of scan rate on the peak current and peak potential of xanthine. Usually, uric acid in the body is generated by xanthine under the catalysis of xanthine oxidase (XOR), and high concentration of uric acid can cause gout. The inhibition for the formation of uric acid is the most direct method for the treatment of gout. Hence, the inhibition for the formation of uric acid by febuxostat and allopurinol was researched by electrochemical method, manifesting febuxostat and allopurinol can inhibit the activity of xanthine oxidase, which did not make xanthine generating uric acid. Thus, this work is very meaningful in the field of the diagnosis and treatment of gout.

Key words: nitrogen doped reduced graphene oxide, chitosan, xanthine, cyclic voltammetry, uric acid, gout