Multiple heteroatom dopant carbon dots as a novel photoluminescent probe for the sensitive detection of Cu2+and Fe3+ions in living cells and environmental sample analysis

Heavy metal ion pollution harms human health and the environment and continues to worsen. Here, we report the synthesis of boron (B), phosphorous (P), nitrogen (N), and sulfur (S) co-doped carbon dots (BP/NS-CDs) by a one-step facile hydrothermal process. The optimum synthetic parameters are of 180 degrees C temperature, 12 h reaction time and 15% of PBA mass. The as-synthesized BP/NS-CDs exhibits excellent water solubility, strong green photoluminescence (PL) at 510 nm, and a high quantum yield of 22.4%. Moreover, BP/NS-CDs presented high monodispersity (7.2 +/- 0.45 nm), excitation-dependent emission, PL stability over large pH, and high ionic strength. FTIR, XRD, and XPS are used to confirm the successful B and P doping of BP/NS-CDs. BP/NS-CD photoluminescent probes are selectively quenched by Cu2+ and Fe3+ ions but showed no response to the presence of other metal cations. The PL emission of BP/NS-CDs exhibited a good linear correlation with Cu2+ and Fe3+ concentrations with detection limits of 0.18 mu M and 0.27 mu M for Cu2+ and Fe3+, respectively. Furthermore, the HCT116 survival cells kept at 99.4 +/- 1.3% and cell imaging capability, when the BP/NS-CDs concentration is up to 300 mu g/mL by MTT assay. The proposed sensor is potential applications for the detection of Cu2+ and Fe3+ ions in environmental water samples.

Automated summary

Boron, phosphorous, nitrogen, and sulfur co-doped carbon dots (BP/NS-CDs) were synthesized via a one-step hydrothermal process. BP/NS-CDs exhibited excellent water solubility, strong green photoluminescence, and high quantum yield. The sensor showed high selectivity and sensitivity towards Cu2+ and Fe3+ ions, making it suitable for the detection of these ions in environmental water samples.