Fabrication and characterization of a folic acid-bound 5-fluorouracil loaded quantum dot system for hepatocellular carcinoma targeted therapy

In the present study, we covalently coupled folic acid (FA) and 5-fluorouracil acetic acid (FUA) on the surface of quantum dots (QDs) to produce a tumor targeting drug delivery system, FA-QDs-FUA. The QDs not only act as hepatocellular carcinoma (HCC)-targeted delivery vehicles, but also play a key role in imaging. The structural and optical properties of as-prepared FA-QDs-FUA were characterized using UV-visible spectra, fluorescence spectra, infrared spectra, particle size and zeta potential. In vitro hemolysis activity, cytotoxicity and targeting specificity of the FA-QDs-FUA system were also evaluated. The in vivo anti-tumor efficacy of FA-QDs-FUA in tumor-bearing mice was investigated. The average particle size and zeta potential of FA-QDs-FUA was 220.28 nm and −13.3 mV, respectively. The drug-loading content of FA-QDs-FUA was 36.85% ± 1.61% (n = 3). The in vitro release profile of 5-FU from FA-QDs-FUA demonstrated a slow and sustained release behaviour as compared to free 5-FU drug. The results of the in vitro cellular experiment demonstrated that FA-QDs-FUA reduced cytotoxicity as compared to free 5-FU and targeted more easily hepatocellular carcinoma cells (SMMC-7721 and HepG2) than normal cells. Mice treated with FA-QDs-FUA showed superior tumor suppression compared to those treated with free 5-FU at 4.72 mg kg(−1) of 5-FU. Therefore, the FA-QDs-FUA system can be used as a promising candidate for improving 5-FU efficacy and tumor targeting specificity with limited toxicity.