Fluorescent Carbon Dots from Cumin Seeds: Preparation, Characterization and In Vitro Biocompatibility Test for Cell Imaging Application

Abstract

Carbon dots (CDs) are a new type of nanomaterial with great potential in bioimaging, biosensing, and drug delivery. In this study, novel CDs were prepared from cumin seeds (Cuminum cyminum L) by pyrolysis. The pyrolysis method and several extraction steps were optimized to fabricate CDs from cumin seed. The size, structure, chemical composition, and photoluminescence properties of the CDs were characterized using size analyzer, zeta sizer, TEM, SEM, EDX, UV-Vis, fluorescence spectroscopy, and FTIR. The influence of the CDs on cell viability was investigated in A549, 3T3, and MCF-7 cell lines using MTT assay. The cancer cell imaging potential of the CDs was assessed using fluorescence microscopy. The results showed that the CDs with a mean diameter of 13.4 ± 3.7 nm and zeta potential of -23.3 ± 7.5 mv can be obtained by the pyrolysis of cumin seed powder. The obtained CDs exhibited strong and unique fluorescence properties when they were excited at different wavelengths, particularly 350 nm. The CDs were highly stable over time, and their fluorescence properties remained unchanged after three months. Apart from the physicochemical properties of the CDs, cell viability assays showed that these CDs were non-toxic to A549, MCF-7, and 3T3 cells, over 90% of the cells were viable after 24 h, even at the highest concentration (1000 µg/ml). The CDs successfully penetrated the MCF-7 cells as revealed by fluorescent images. Taken together, the fluorescent CDs derived from cumin seeds through the presented facile technique indicated excellent and stable fluorescence properties. In addition, these CDs were highly biocompatible in vitro and could be a potential option for theragnostic applications.