▎ 摘　　要

Glutamic acid and histidine functionalized graphene quantum dots (Glu-GQD-His) were synthesized by pyrolysis of the mixture of citric acid, glutamic acid and histidine. The resulting Glu-GQD-His was composed of 2-3 layers of graphene sheets with an average size of (3.85 +/- 0.15) nm and rich functional groups. Glu-GQD-His could offer a strong blue fluorescence emission under visible light excitation, which was higher than that of graphene quantum dot (GQD) made via pyrolysis of citric acid. The results demonstrated that the introduction of glutamic acid and histidine could improve the optical properties. As an optical probe, Glu-GQD-His was of a low toxicity and could be used for cell fluorescence imaging. As an artificial peroxidase, Glu-GQD-His could catalyze the oxidation of 3 , 3' ,5 , 5'-tetramethylbenzidine with H2O2 to produce corresponding blue oxidation product. The Michaelis constant (K-m) reached 1.110 mmol/L, which was significantly lower than that of horseradish peroxidase (3.702 mmol/L) and GQD (1.443 mmol/L). This verified that Glu-GQD-His had a better catalytic activity. Based on the above catalytic reaction, the colorimetric method for determination of H2O2 was established. In the concentration range of 0.0011.0 mmol/L, the absorbance of blue oxidation products would increase linearly with increasing H2O2 concentration. The detection limit of the method was 0.4 mu mol/L. The as-proposed method provided better sensitivity and selectivity compared with the present analytical methods, and was successfully applied to detection of H2O2 inside and outside tumor cells.