▎ 摘　　要

Green and low-cost photoluminescent graphene quantum dots (GQDs) were prepared by a one-step hydrothermal method with konjac glucomannan (KGM), a natural polysaccharide, as the precursors. Then, the folic acid (FA)-functionalized GQDs (FA-GQDs) was formed by the amidation of GQDs with FA, and the drug carrier named as FA-GQDs-DOX was obtained by loading doxorubicin (DOX) on FA-GQDs. Due to the inherent fluorescence properties of GQDs and DOX in FA-GQDs-DOX, the resultant samples could be used to selectively label cancer cells without external dyes, and the cellular uptake and the drug-releasing behavior could be visualized. The coupling of FA with GQDs and the loading of DOX on FA-GQDs were confirmed by various means. In addition, the cell imaging showed that the FA-GQDs could be used as a fluorescent probe to recognize folate receptor (FR)-positive cancer cells and that the FA-GQDs-DOX could selectively deliver DOX to FR-positive cancer cells. As a result, the FA-GQDs-DOX could be applied in early diagnosis and targeted therapy of cancer.