FRET‐Responsive Carbon Dots from <i>Ricinus communis</i> for Curcumin Detection and Bioimaging

Abstract This study presents the green synthesis of multifunctional and fluorescent Ricinus communis leaf‐derived carbon dots (RCL‐CDs) and explores their applications in Förster resonance energy transfer (FRET)‐based sensing of curcumin and bioimaging in cancer cells. RCL‐CDs were synthesized via a one‐step pyrolysis method and characterized using HRTEM, FTIR, XRD, UV–vis, and fluorescence spectroscopy. Their quantum yield, zeta potential, and photoluminescence lifetime were evaluated. The carbon dots were utilized for curcumin detection via a FRET‐based mechanism and applied to biological matrices, including turmeric powder and plasma samples. Cytotoxicity and bioimaging were assessed on MCF‐7 and HDF cells using the MTT assay and confocal microscopy. The synthesized RCL‐CDs exhibited excitation‐dependent fluorescence, with maximum emission intensity at 436 nm upon excitation at 342 nm and a quantum yield of 7.04%. Curcumin was selectively detected with a limit of detection (LOD) of 0.033 µM, outperforming conventional techniques. Bioimaging results revealed non‐toxic behavior toward HDF cells and selective cytotoxicity toward MCF‐7 breast cancer cells (IC50: 1.85 mg/mL), with clear intracellular uptake and fluorescence. RCL‐CDs derived from R. communis leaves present a sustainable and eco‐friendly platform for dual‐purpose curcumin sensing and cancer bioimaging. Their biocompatibility, optical performance, and selectivity suggest strong potential for future biomedical applications.