Graphene quantum dots(GQD)with photoluminescence using graphite which the size is no more than 15 nm were synthetized by oxidation reaction and then hydrothermal process,separately.The microstructure and morphology of the samples were characterized by FT-IR,X-ray diffraction patterns(XRD),X-ray photoelectron spectroscopy(XPS),field emission scanning electron microscopy(SEM),transmission electron microscopy(TEM)and atom force microscopy(AFM).The graphene oxide quantum dots(GOQD)shows deep red under ultraviolet(UV)light which has not been reported.The hydrothermal treatment based on GOQD was carried on at different temperatures.Comparing with the large synthesinano graphene oxide(GO)with the red photoluminescence directly and prepared graphene quantum dots(GQD)with the blue photoluminescence under various conditions.The GQD samples prepared at different temperatures indicates the blue photoluminescence intensity of the solution improved radically as the heating temperatures increased.Concerning PL peak and intensity of the quantum dots,the results demonstrate dependence on time under heating,temperature of heating,and pH adjusted by the addition of sodium hydroxide.The FT-IR measurements and absorption spectrum indicate that the functional groups of graphene oxide were altered due to the hydrothermal synthesis routes.The SEM images illustrate the stacking configuration and self-assembled structure of the graphene sheets.The TEM investigation shows that graphene quantum dots tend to be planar with obvious wrinkles revealed at the edge structures.In addition,absorption,PL,and PLE spectra of the graphene quantum dots increase with larger quantities of sodium hydroxide added.Finally,graphene quantum dots to target PNTIA cells were carried out successfully.High uptake efficiency and no cytotoxic effects both indicate that graphene quantum dots can be suitability for bio-targeting.