▎ 摘　　要

Polyethylene glycol (PEG) functionalized graphene quantum dots (GQDs-PEG) with average particle size of 2.1 nm were successfully prepared by hydrothermal method with PEG as surface passivation agent. The quantum yield (QY) of GQDs-PEG was 3.7%and its physiological stability was significantly better than that of GQDs. The cell viability assay results showed that GQDs-PEG display no obvious toxicity to cells. The results of cell fluorescence imaging showed that GQDs-PEG could enter the whole cell with high fluorescence recognition.