▎ 摘　　要

Graphene quantum dots (GQDs) are new efficient nanomaterials used in therapeutic applications. In this study, blue fluorescent nitrogen-doped GQDs (N-GQDs) were synthesized by a hydrothermal method via pyrolisis of citric acid as the carbon source and urea as the nitrogen source. The existence of doped nitrogen in GQDs was confirmed by FTIR characterization. Here, for the first time, the N-GQDs were loaded with the anticancer drug, methotrexate (MTX), to prepare MTX-(N-GQDs) as an efficient drug delivery system. The establishment of the strong pi-pi stacking interaction between MTX and N-GQDs was confirmed by FTIR and UV-vis spectroscopies indicating successful loading of MTX to N-GQDs. The in-vitro cytotoxicity of MD(-(N-GQDs) on human breast cancer cells investigated through MIT assay suggested that the drug-free N-GQDs nanocarriers are highly biocompatible, whereas the MIX-loaded ones are more cytotoxic than the free MTX. (C) 2017 Elsevier B.V. All rights reserved.