Nitrogen-doped carbon dots as a fluorescent probe for the highly sensitive detection of Ag and cell imaging.

An easy hydrothermal synthesis strategy was applied to synthesize green-yellow emitting nitrogen-doped carbon dots (N-CDs) using 1,2-diaminobenzene as the carbon source, and dicyandiamide as the dopant. The nitrogen-doped CDs resulted in improvement in the electronic characteristics and surface chemical activities. N-CDs exhibited bright fluorescence emission and could response to Ag selectively and sensitively. Other ions produced nearly no interference. A N-CDs based fluorescent probe was then applied to sensitively determine Ag with a detection limit of 5 × 10  mol/L. The method was applied to the determination of Ag dissolved in water. Finally, negligibly cytotoxic, excellently biocompatibile, and highly fluorescent carbon dots were applied for HepG2 cell imaging and the quenched fluorescence by adding Ag , which indicated its potential applications.