Facile synthesis of oxygen and sulfur co-doped graphitic carbon nitride fluorescent quantum dots and their application for mercury(II) detection and bioimaging

In this work, uniform oxygen and sulfur co-doped graphitic carbon nitride quantum dots (OS-GCNQDs) have been prepared by thermal treatment of citric acid and thiourea. The asobtained OS-GCNQDs show strong blue photoluminescence (PL) with a relatively high quantum yield of 14.5%. Furthermore, OS-GCNQDs exhibit stable and specific concentration-dependent PL intensities in the presence of mercury(II) ions in the range of 0.001-20.0 mu M, with a detection limit of 0.37 nM (3S/N). More importantly, OS-GCNQDs were explored for cell imaging with satisfactory biocompatibility, and so are a potential fluorescent probe in biosensing and bioimaging applications.