Large Emission Red-Shift of Carbon Dots by Fluorine Doping and Their Applications for Red Cell Imaging and Sensitive Intracellular Ag+ Detection

Heteroatom doping is one of the most effective routes to adjust the physicochemical and optical properties of carbon dots (CDs). However, fluorine (F) doped CDs have been barely achieved. In this work, a F-doping strategy was proposed and adopted to modulate optical properties of CDs. A kind of F-doped CDs was synthesized by a solvothermal process using aromatic F bearing moiety as the F source and shows much longer maximum emissions (up to 600 nm, red fluorescence) than that of undoped CDs, indicating a large emission red-shift effect by F-doping. In addition, the F-doped CDs have remarkable water-solubility, high biocompatibility, as well as excellent stability even under broad pH range, ionic strengths, and light illumination and thus can be used as a novel probe for the highly efficient cell imaging of various normal cells and cancer cells. The F-doped CDs can selectively bind to Ag+. It therefore makes the F-doped CDs be a highly sensitive probe for the detection of Ag+ under both aqueous solution and various biological systems. The huge potential of this F-doping strategy is indicated in the rational design of high-performance CDs, as well as in applications of clinical diagnosis and ion detection.