One-step synthesis of nitrogen, sulfur co-doped carbon nanodots and application for Fe detection.

Carbon nanodots (CDs) are novel forms of zero-dimensional carbonaceous nanomaterials, which have attracted the attention of researchers. Long wavelength emission decreases the interference of auto-fluorescence of tissue and can also penetrate more deeply. However, it is still a challenge to develop red emissive CDs. In this work, nitrogen, sulfur co-doped CDs are synthesized with red light emission through one-step solvothermal treatment. The as-synthesized CDs exhibit excellent properties such as high chemical stability, good biocompatibility, excellent photoluminescence properties, good water solubility, and low toxicity, and also show high sensitivity and selectivity towards Fe sensing. The detection limit is as low as 17.3 nM. In addition, the CDs are successfully utilized for monitoring Fe in living cells, which demonstrates their promising applicability in bioimaging. Furthermore, a test paper based on the CQDs has been prepared. This developed nanosensor can detect Fe visually and sensitively without any further steps which will make a great contribution to the development of ion sensors.