▎ 摘　　要

In this study, we successfully synthesized polyethylene glycol (PEG) and folic acid (FA) co-functionalized graphene quantum dots (GQDs) to improve the biocompatibility and tumor-targeting ability of GQDs simultaneously, and labeled GQDs-PEG-FA with I-131 for biological behavior evaluation. The in vitro properties, biodistribution and SPECT imaging of I-131-GQDs-PEG-FA were investigated. The uptake of I-131-GQDs-PEG-FA at tumor sites can be clearly examined via SPECT imaging, which can ascribe to enhanced permeability and retention effect and active targeting effect of FA to folate receptors. The results indicate that I-131-GQDs-PEG-FA can be used as a radioactive probe for detection of tumor cells overexpressing folate receptor.