Highly fluorescent N,S-co-doped carbon dots: synthesis and multiple applications

Abstract

In this study, N and S co-doped carbon dots (N,S-CDs) were synthesized from biomass, using sulfamic acid as a passivator. The N,S-CDs have satisfying fluorescence properties with a quantum yield of 24.1%. It has been shown that the N,S-CDs have low cytotoxicity and can be used as multicolor probes for cell imaging. In addition, the N,S-CDs have excellent antioxidant abilities for scavenging DPPH free radicals, hydroxyl free radicals and superoxide anion free radicals. Moreover, the fluorescence of the N,S-CDs can be quenched by Cr(VI) because of the inner filter effect (IFE). Accordingly, the fluorescence response for this Cr(VI) assay leads to a broad linear range of 1 to 200 μM, associated with a limit of detection of 0.76 μM. Furthermore, this N,S-CD-based fluorescence platform for Cr(VI) detection was successfully applied in real lake water, human serum and living cells.