Synthesis of highly fluorescent, amine-functionalized carbon dots from biotin-modified chitosan and silk-fibroin blend for target-specific delivery of antitumor agents

Carbon dots (CDs) have been a promising theranostic tool with high biocompatibility and a tailorable fluorescence profile. Herein, we report the synthesis of highly fluorescent amine-functionalized CDs from low molecular weight chitosan (LMWC) and silk-fibroin (SF) blends. The synthesized CDs were quasi-spherical in shape with a size of 3 +/- 1.5 nm. A significant increase in fluorescent intensity and quantum yield was achieved upon increasing the SF content due to nitrogen doping. For inducing target specificity to cancer cells, biotin was covalently conjugated to the CDs, and the conjugation was determined by FTIR spectroscopy. The conjugate was further loaded with 5-fluorouracil (5-FU) as a model anti-cancer drug. The MTT assay showed increased cytotoxicity of the conjugated CDs in cancer cells compared to normal cells. The live-cell imaging in MCF-7 cell lines showed bright blue-colored fluorescence and increased internalization of the conjugated CDs than the nonconjugate ones due to receptor-mediated endocytosis.

Automated summary

Carbon dots (CDs) with high biocompatibility and fluorescence were synthesized from low molecular weight chitosan and silk fibroin blends. Biotin was covalently conjugated to the CDs to increase target specificity to cancer cells, and the conjugated CDs showed increased cytotoxicity and internalization in cancer cells compared to normal cells. The study demonstrates the potential of functionalized CDs as a theranostic tool for cancer treatment.