Synthesis of folic acid conjugated photoluminescent carbon quantum dots with ultrahigh quantum yield for targeted cancer cell fluorescence imaging.

Folic acid functionalized carbon quantum dots (FA-CQDs) with ultrahigh quantum yield (50 %) were synthesized by one-pot hydrothermal route using citric acid. The synthesized CQDs were characterized by fluorescence spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS) and X-ray diffraction. The cell viability of about 95 % and 97 % were obtained for MTT assay of the CQDs and FA-CQDs toward MCF-7 cells after 24 h of incubation respectively. The FA-CQDs were successfully applied for targeted imaging of ovarian cancer (type HeLa) and human breast adenocarcinoma (type MCF7) cells using fluorescence microscope.