Preparation and characterization of B, S, and N-doped glucose carbon dots: Antibacterial, antifungal, and antioxidant activity

Carbon dots are prepared using glucose as a carbon source (GCD) and doped with heteroatoms such as boron, sulfur, and nitrogen to enhance their functionality. FTIR and XPS results confirm doping of GCDs with heteroatoms, and their particle size is ~10 nm, as shown by TEM images. GCDs are very hydrophilic and stable in an aqueous solution, and nitrogen-doped GCD (NGCD) exhibits the highest polydispersity index of 0.274. The GCDs show excellent tunability of the PL emission with the variation in excitation wavelength. All the GCDs display excellent antioxidant function with the highest activity in the NGCD. The boron-doped GCD (BGCD) and sulfur-doped GCD (SGCD) exhibit more potent antibacterial activity against E. coli and Listeria monocytogenes. The NGCD is effective against both bacterial strains, showing the highest antibacterial activity. The NGCD exhibits potent antifungal activity against Ammophilus fumigatus, P. citrinum, C. albicans, and R. rubra, while the SGCD has a higher inhibitory effect on the growth of F. solani. Besides, more than 80% of the mouse fibroblast L929 cells are viable even when exposed to a high concentration of 500 μg/mL for 72 h, indicating low toxicity.