Novel fluorescent probes based on nitrogen-sulfur co-doped carbon dots for chromium ion detection

In this work, novel carbon dots codoped with nitrogen and sulfur (NSCDs) were used as fluorescent probes to detect Cr3+. These NSCDs exhibited strong fluorescence, which could be rapidly quenched by Cr3+. The fluorescence intensity of the NSCD solutions would decrease linearly with increasing Cr3+ concentration (0-40 mu M). The detection limit was calculated to be 7.8 nM, indicating that the NSCD probes have excellent sensitivity. Then, it was determined that the NSCD probes were quenched only by Cr3+, even in the presence of other ions, thereby showing that the NSCD probes possess excellent anti-interference ability and selectivity. The mechanism of quenching of the fluorescence of NSCDs by Cr3+ ions may be related to the enhanced non-radiation emission attributed to the destroyed NSCD surface. Due to their nontoxicity and biocompatibility, these NSCDs could be applied in the detection of Cr3+ in living cells.