Sustainable carbon quantum dots enhanced photoluminescence for bioimaging applications: An in vitro and in silico analysis

Abstract

This study explores the synthesis and characterization of glucose-based carbon quantum dots (CQDs) for potential applications in the field of photoluminescence. The unique properties of CQDs are investigated, highlighting their distinct features compared to traditional carbon dots. Here, commercially available L-glucose is a precursor that has been chosen as the starting material to produce fluorescent carbon quantum dots (CQDs). The low to high quantum yield CQDs were reduced by chemical reduction method using sodium borohydride and then thiol (L-cysteine) induced for the stabilizer to stabilize rigidified reduced CQDs-L-cysteine (r-CQDs-Cys). The effect of pH and the ligand effect have been investigated for the photoluminescence (PL) studies of r-CQDs-Cys, yielding emission responses that were tuned according to the pH and ligand. The optimized CQDs to r-CQDs-Cys shows the quantum yield (QY) increased from 8.56 % to 42.72 %. The fluorescent QY of the synthesized CQDs investigated for the cytotoxicity test explicates that 90 % of the cells (MCF7) maintain their normal morphology even at higher concentrations of r-CQDs-Cys at 100 µg/mL. This Cytotoxicity test suggests that r-CQDs-Cys are non-toxic biocompatible and the binding energy value −6.8 kcal/mol of the carbon quantum dots was confirmed by in-silico studies. A total of 13 hydrogen bonds, 2 carbon bonds, and one Pi bond were formed during the interaction of the MCF7 cancer cell line with carbon quantum dots. The overall results confirmed that r-CQDs-Cys enhanced QY, fluorescence emission, and superior water solubility of the while compared to others which made them suitable for bio-imaging applications.