Fluorescent Carbon Dots as Biosensor, Green Reductant, and Biomarker.

Carbon dots, the celebrated green material among the nanocarbon family, are blessed with several interesting features like biocompatibility, solubility, tunable luminescence, and so forth. Herein, carbon dots derived from Mint leaf extract (M-CDs) via a green method are exploited for versatile applications as a biosensor, reductant, and biomarker. M-CDs are applied for fluorimetric sensing of biologically relevant folic acid through quenching response originating from the inner filter effect, with a limit of detection of 280 nM. The carbon dots were highly selective toward folic acid in a collection of 16 biomolecules. The specificity of carbon dots toward folic acid is explained based on the interaction between the two. Along with sensing, herein, we project M-CDs as a green reducing agent by demonstrating the reduction of Fe(III) and noble metal nanoparticle synthesis from their salt solutions. The particles are found to be significantly non-cytotoxic, as evident from the MTT assay performed on primary H8 cells. The application of M-CDs in multicolor imaging is also illustrated using HeLa cells.