Synthesis of Fluorinated and Nonfluorinated Graphene Quantum Dots through a New Top-Down Strategy for Long-Time Cellular Imaging

Graphical Caught on camera : By combining a microwave-assisted technique with hydrothermal treatment and using fluorinated graphene oxide (FGO) as a raw material, fluorinated graphene quantum dots (GQDs) and nonfluorinated GQDs are synthesized (see figure). Fluorinated GQDs show improved pH and photostability compared with nonfluorinated GQDs due to fluorine. Fluorinated GQDs are suitable for long-term cellular imaging. Herein, a new strategy has been developed through combining a microwave-assisted technique with hydrothermal treatment to reduce graphene waste and improve production yield of graphene quantum dots (GQDs) prepared by top-down methods. By using fluorinated graphene oxide (FGO) as a raw material, fluorinated GQDs and nonfluorinated GQDs can be synthesized. Additionally, in the fluorinated GQDs, the protective shell supplied by fluorine improves the pH stability of photoluminescence and the strong electron-withdrawing group,  F, reduces the π- electron density of the aromatic structure; thus inhibiting reactivity toward singlet oxygen produced during irradiation and improving the photostability. Therefore, the as-prepared fluorinated GQDs with excellent photo- and pH stability are suitable for long-term cellular imaging.