Fabrication of FA/HA-functionalized carbon dots for human breast cancer cell targeted imaging.

Green fluorescent carbon dots (CDs) were prepared by one-step hydrothermal method and then modified into folic acid functionalized carbon dots (FA-CDs) and hyaluronic acid functionalized carbon dots (HA-CDs) with targeted function to study their application in breast cancer cells imaging. The microstructure of the CDs observed through TEM showed the CDs with a scale of 2.69 nm. FT-IR and XPS showed the changes of bonds and functional groups that confirmed the transformation of COOH and NH2 to amide bonds. FA-CDs and HA-CDs had good water solubility and cytocompatibility, which laid a foundation for their application in human breast cancer cells imaging. At the same time, FA-CDs and HA-CDs had strong fluorescence excitation, and the optimal emission wavelength was about 450 nm. In fluorescence imaging of cells, carbon dots had bright green fluorescence in both breast cancer cells (MCF-7 cells) and normal cells (EC cells). After targeted endocytosis, FA-CDs and HA-CDs could emit bright green fluorescence in cancer cells but could not in normal cells, which proved that the synthesized FA-CDs and HA-CDs had targeting properties. FA-CDs and HA-CDs could be used to accurately identify breast cancer cells and normal cells as cancer diagnosis material, which had the potential application in early cancer diagnosis.

Hyaluronic acid conjugated nitrogen-doped graphene quantum dots for identification of human breast cancer cells.

Accurate distinguish of cancer cells through fluorescence plays an important role in cancer diagnosis. Here we synthesized a blue fluorescent nitrogen-doped graphene quantum dots (N-GQDs) from citric acid and diethylamine via one-step hydrothermal synthesis method which was simple and quick to avoid by-products, and highlighted the binding sites to achieve precise combination. Due to the nitrogen element doping, amide II bond was amply obtained and abundant binding sites were provided for hyaluronic acid (HA) conjugation. N-GQDs solution with different pH value was then conjugated to HA via an amide bond for the recognition of human breast cancer cells (MCF-7 cells), and the formation of amide bond was more favorable under alkaline conditions. HA conjugated N-GQDs (HA-N-GQDs) were combined with CD44 which was over expressed on the surface of MCF-7 cells, resulting in MCF-7 cells performing stronger fluorescence. HA-N-GQDs showed high fluorescence, low toxicity, and good cytocompatibility, which held it play a role in fluorescence imaging for accurate identification of cancer cells.