Microwave-assisted sustainable synthesis of yellow emissive carbon dots for selective sensing of Hg (II) ions and cancer cell imaging

Microwave-assisted synthesis of water-soluble yellow emissive carbon dots (YECDs) of similar to 2.8 nm size has been synthesized using m-phenylenediamine and malonic acid. YECDs show excitation-independent emission properties and display the maximum fluorescence intensity at 550 nm when excited at 420 nm excitation with a high quantum yield of similar to 21 %. The water-soluble YECDs are used for selective sensing of Hg2+ metal ions in aqueous media even in the presence of other interfering metal ions with a good limit of detection of similar to 191 nM. For field application purposes, the YECDs-coated paper strips are used for selective sensing Hg2+ ions. In addition, YECDs were successfully used to measure the content of Hg2+ metal ions in potable water and industrial wastewater samples. Finally, we have proposed the quenching mechanism of YECDs in the presence of Hg2+, which occurred via both static and dynamic quenching mechanisms through the interaction of Hg2+ ions with the functional group present in YECDs. Moreover, highly emissive, low-toxic YECDs are used for cancer cell imaging under blue light and can be further developed for the subcellular targeting probe.