Green synthesis of multifunctional fluorescent carbon dots from mulberry leaves (Morus alba L.) residues for simultaneous intracellular imaging and drug delivery

Fluorescent carbon dots (CDs) were directly synthesized by hydrothermal treatment of medicinal mulberry leaves (Morus alba L.) residues without the need for any chemical reagent. The CDs were collected successively through filtration, centrifugation, and dialysis from the resultant solution. The as-purified CDs were almost non-cytotoxic and successfully used for the intracellular fluorescence imaging of human hepatocellular carcinoma cells (HepG2). Due to the presence of plentiful surface groups, the CDs were further used as drug carriers for the loading of Lycorine, an anti-cancer alkaloidal extracted from bulbs of Lycoris radiata L. Importantly, the Lycorine-loaded CDs were successfully applied for simultaneous intracellular imaging and drug delivery for the better anti-cancer cell activity. The present work both provides a strategy for the reuse of medicinal herb residues for the preparation of CDs and promotes a potential application of CDs in biomedicine and bioimaging.