Synthesis of cell-penetrated nitrogen-doped carbon dots by hydrothermal treatment of eggplant sepals

Novel nitrogen doped carbon quantum dots were successfully fabricated by a hydrothermal method with eggplant sepals as carbon source. The carbon materials were characterized by transmission electron microscopy (TEM), UV-Vis adsorption, Fourier-transformed infrared spectroscopy (FTIR), fluorescence and the X-ray photoelectron spectroscopy (XPS) measurements, respectively. The carbon quantum dots showed excellent photoluminescence property with high stability in phosphate buffer solution with different pH values from 5 to 9, even in the cell culture medium supplied with the fetal bovine serum. Meanwhile, we also studied the interaction of carbon quantum dots with living HeLa cells with confocal microscopy. Our results indicated that the carbon quantum dots can enter the living HeLa cells by cellular penetration.