Bio-Conjugated Carbon Quantum Dots for Intracellular Uptake and Bioimaging Applications

Carbon quantum dots (CQDs) demonstrate outstanding biocompatibility and optical properties, making them ideal for monitoring cellular uptake. Due to their ultra-small size (typically < 10 nm) and fluorescent nature, CQDs hold significant potential as nanoparticles for bioimaging and tracking intracellular processes. The study examined the optimization parameters for conjugating calf thymus DNA (Ct-DNA) to CQDs to facilitate Ct-DNA internalization in mouse fibroblast cells (L929) and human breast cancer cells (MCF-7). The formation of the CQD-Ct-DNA complex was confirmed by various characterization techniques such as, UV-Vis spectroscopy, fluorescence spectroscopy, transmission electron microscopy, and zeta potential analysis. The CQD-Ct-DNA complex, at a 600 µg/mL concentration, demonstrated up to 83.7% cell viability for the L929 cell line and 75.6% for the MCF7 cell lines. The research also compared the transfection ability of CQD with commonly used transfection agents lipofectamine and Polyethyleneimine (PEI) for Ct-DNA internalization. The results demonstrated that CQD could efficiently internalize Ct-DNA compared to the other agents. Thus, the CQD-Ct-DNA complex shows promising potential in bioimaging applications as an effective non-viral vector.