Preparation and application of carbon dots with tunable luminescence by controlling surface functionalization

Carbon dots (CDs) were prepared by a simple hydrothermal method using citric acid, potassium persulfate, and trishydroxymethylaminomethane as precursors. By adjusting reaction temperature, surface defects of the prepared CDs are modulated. The CDs emit green, yellow, and red fluorescence under the irradiation of a 365 nm ultraviolet lamp. In addition, the CDs are nearly spherical particles and have high stability in aqueous solution, and good biocompatibility, and thus have been applied successfully as a sensor to selectively detect Hg2+ and as a fluorescent bioimaging reagent.