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-3T3

The presence of mercury (Hg(II)) and arsenic (As(III)) in drinking water poses a substantial threat to public health. Mercury exposure can lead to neurological and developmental impairments, while arsenic is a known carcinogen, linked to skin, lung, and bladder cancers among other health issues. Given these significant risks, it is imperative to develop highly efficient, sensitive, and reliable methods for the detection and quantification of these heavy metals in drinking water. In this study, a novel fluorometric sensor based on chlorophyll-rich carbon quantum dots (CQDs) for the detection of Hg(II) and As(III) ions were developed. The dual emitting (blue-green and red) CQDs were synthesized by a one-step solvothermal method using plumeria plant leaves as precursors. When Hg(II) ions were added to CQD solution, the red emission (676 nm) of the CQDs was quenched (OFF), while in the case of of As(III) ions, the blue-green emission (485 nm) was enhanced (ON). The detection limits of 0.99 nM for Hg(II) and 12.15 nM for As(III) 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 Hg(II) and As(III) ions. Moreover, the novel chlorophyll-rich CQD-based fluorometric “ON–OFF” dual probe sensor was successfully applied to detect Hg(II) and As(III) in real water system as well as in the mouse fibroblast cell line.