One-pot synthesized multifunctional carbon nitride dots for fluorescent sensing, bioimaging, and selective cytotoxic effect on cancer cells

Heavy metals are one of the significant contributors to environmental pollution; they can occur naturally or through anthropogenic activities. On the other hand, antibiotics are emerging contaminants that can pollute water bodies. In the present work, versatile metal-free oxygen-doped carbon nitrides dots (O-GCNQD) having multiple applications like rapid fluorescent sensing of heavy metal mercury (Hg2+), antibiotic tetracycline (TC), in-vitro cellular imaging, and selective cytotoxicity for cancerous cells have been developed. In the first part of the work, the intrinsic property exhibited by O-GCNQDs is used in the selective and sensitive sensing of Hg2+ and tetracycline. Additionally, iodide ion (I-) sensitivity is employed to reverse fluorescence quenched by Hg2+ inducing 'on-off' fluorescence. The metal and drug detection limit was 250 nM and 410 nM, respectively. The sensor could sense more than 98.7 % of respec-tive metal ions and drug molecules in spiked actual water samples. There is a lot of study on carbon dots (CD) in nanomedicine, particularly in imaging and drug administration. Still, there is less focus on its intracellular activity and possible anticancer processes. So in the second part, the biological applications of O-GCNQDs are explored. Their bright green fluorescence in long UV and biocompatibility were inves-tigated for imaging of cancer cells. The cytotoxic studies showed the carbon dots have exceptional selec-tive toxicity towards cancer B16 murine melanoma cells compared to fibroblast cells. The anticancer studies also reveal that our carbon dots could induce cell apoptosis at lower concentrations without external stimuli like light or heat.(c) 2022 Elsevier B.V. All rights reserved.