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 seeds. The size, structure, chemical composition, and photoluminescence properties of the CDs were characterized using a size analyzer, TEM, SEM, EDX, UV-Vis, fluorescence spectroscopy, and FTIR. The influences of the CDs on cell viability were investigated in A549, 3T3, and MCF-7 cell lines via 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 13.42 nm could be obtained through the pyrolysis of cumin seeds. The obtained CDs exhibited strong and unique fluorescence properties once they were excited at different wavelengths, particularly at 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 CD, 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 indicated excellent and stable fluorescence properties. In addition, these CDs were highly biocompatible and could be a potential option for theragnostic applications.