Evaluation of Biological Activities of Carbon Nanodots

Abstract

Carbon nanodots, due to their unique physicochemical properties have various applications in the field of biomedical sciences. Ranging from 1 to 20nm in size, the unique spherical quantum dots obtained from chemical and biological sources of carbon are significant for their striking fluorescence, a zero-dimensional morphology, homogeneity in size, the flexibility of surface passivation and for the promise of biocompatibility. These nanodots can be synthesized through a number of prescribed methods including the chemical methods of carbonization and the physical methods of breaking apart a carbon source using laser, heat or ultrasonic waves. This study has adopted the hydrothermal method with a Teflon-lined autoclave to synthesize CNDs by sealing ascorbic acid solution (carbon source) inside the autoclave and leaving it at 250°C for four hours. These nanodots were characterized with UV-Vis spectral analysis which gave a peak at 320nm and then another smaller one at 400nm. XRD displayed crystalline properties while SEM confirmed a spherical morphology and exceptionally small size of the nanodots. FTIR analysis showed the functional groups present at the surface of these nanodots which primarily included hydroxyl, aldehydic, ketonic and carboxylic groups. Antimicrobial activity against Escherichia coli, Staphylococcus aureus and Klebsiella pneumonia and antioxidant activity using DPPH assay were also determined to ascertain the possible applications for the synthesized CNDs. An almost non-existent cytotoxicity was determined through MTT assay to confirm that the synthesized CNDs were biocompatible. CNDs synthesized, characterized and evaluated here can be used for further applications in the field of biomedicine.