Curcumin Conjugated Carbon Quantum Dots: A Theranostic Probe to Study BSA Interaction, Cellular Imaging, and RICS-Based Intracellular Transport

Plant-based products such as jamun leaves and herbaceous perennials like turmeric are replete with carbon-rich elements, and our recent focus has been directed to synthesizing Carbon Quantum Dots (CQDs) in a low-cost, straightforward, and sustainable method, with their biological and therapeutic applications. A valuable insight we have gained from our results is the environmentally friendly production of CQDs with their distinct physicochemical characteristics, in addition to excellent water solubility and remarkable stability. The as-synthesized CQDs manifest good quantum yields with many potential applications. Moreover, for the stability and enhancement of the solubilization of the hydrophobic drug curcumin, to improve its uptake and bio accessibility, CQDs are a unique choice. After the conjugation of CQDs with curcumin (C-CQDs), the findings we have obtained with partially unfolded BSA demonstrate a modest interaction involving dynamic quenching, as exemplified by steady-state and time-resolved fluorescence quenching driven by Forster Resonance Energy Transfer (FRET). In addition to that, our research also delved into the application of in vivo bioimaging, and by using that fluorescence imaging technique, we introduced Raster Image Correlation Spectroscopy (RICS) techniques to find the diffusion of both CQDs and C-CQDs in the live cell. The study also reaffirms the inherent biocompatibility and antibacterial ability confirmed by the MTT-based cytotoxicity assay and MIC study.