Facile synthesis of sulfur and oxygen co-doped graphitic carbon nitride quantum dots for on-off detection of Cuin real samples and living cells.

A fluorescent sulfur and oxygen co-doped graphitic carbon nitride quantum dots (S,O-CNQDs) were prepared from ethylenediaminetetraacetic acid disodium salt dihydrate and thiourea as the carbon and sulfur sources. The morphology and surface functional groups of S,O-CNQDs were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The fluorescence of S,O-CNQDs could be quenched efficiently by Cuunder the optimum conditions. The S,O-CNQDs could function as an excellent fluorescent probe for Cudetection with a wide linear range of 0.50-15M and a low detection limit of 0.58 nM. In addition, this fluorescent probe was employed for monitoring Cuin samples of tap water, lake water, human serum and urine with good recoveries from 99.0% to 110.0%. Moreover, the S,O-CNQDs with high cell penetration and low cytotoxicity were utilized for Cudetection in living cells. Owing to the excellent properties of S,O-CNQDs, the as-prepared S,O-CNQDs can be a potential candidate for biological applications.