Biogenic synthesis of dual-emission chlorophyll-rich carbon quantum dots for detection of toxic heavy metal ions – Hg(ii) and As(iii) in water and mouse fibroblast cell line NIH-3T3Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d3en00789h

Due to the excessive residues and serious adverse effects, it is urgent to develop an efficient method to detect Hg2+and As3+in drinking water to protect human health. In this study, a novel fluorometric sensor based on chlorophyll-rich carbon quantum dots (CQDs) for the detection of Hg2+and As3+ions was developed. The dual emitting (blue-green and red) CQDs were synthesized by a one-step solvothermal method using plumeria plant leaves as precursors. When Hg2+ions were added in the presence of CQDs, the red emission (676 nm) of the CQDs was quenched (OFF), while in the presence of As3+ions, the blue-green emission (485 nm) was enhanced (ON). The detection limits of 0.99 nM for Hg2+and 12.15 nM for As3+were validated for the proposed sensor. The biocompatibility, cytotoxicity, and bioimaging of the CQDs were investigated in the mouse fibroblast cell line NIH-3T3. The cellular uptake was also studied under the influence of Hg2+and As3+ions. Moreover, the novel chlorophyll-rich CQD-based fluorometric “ON–OFF” dual probe sensor was successfully applied to detect Hg2+and As3+in real water systems as well as in the mouse fibroblast cell line.