Red-Emissive Carbon Dots for “Switch-On”Dual Function Sensing Platform Rapid Detection of Ferric Ions and l‑Cysteine in Living Cells

Ferric ions (Fe3+ ions) and l-cysteine (( l-Cys) in the human body have always played an irreplaceable role in biological processes, and overload or deficiency of Fe3+ ions and l-Cys in the biological system leads to various diseases. In this work, N,S-co-doped red-emitting carbon dots (R-CDs) were synthesized by a facile hydrothermal method. Because the doping of N and S gives a unique functional group distribution on the surface of R-CDs, it can be complexed with Fe3+ ions to construct an energy transfer quenching system. However, the presence of l-Cys competitively binds to Fe3+ ions, thus resulting in the photoluminescence recovery of R-CDs. Therefore, a “switch-on” dual function sensing platform has successfully been developed based on R-CDs for rapid identification and quantification of Fe3+ ions and l-Cys. The linear detection range of Fe3+ ions is 0–30 μM (limit of detection (LOD): 0.27 μM) and that of l-Cys is 0–24 μM (LOD: 0.14 μM). The sensor platform was used to detect Fe3+ ions and l-Cys in h...