OBJECTIVETo assess the cytotoxicity of carbon-coated iron nanoparticles (CCIN) and epirubicin-loaded CCIN on Hep-G2 cells in vitro and compare the acute toxicities of epirubicin and epirubicin-loaded CCIN in mice.

METHODSThe cytotoxicities of CCIN and epirubicin-loaded CCIN on HepG2 cells were assessed using MTT assay, and the uptake of CCIN by the tumor cells was observed by optical and electron microscopy. Different doses of epirubicin and equivalent doses of epirubicin-loaded CCIN were injected intravenously in mice to compare their acute toxicities.

RESULTSOptical and electron microscopy revealed cytoplasmic uptake of CCIN in the tumor cells without obvious destruction of the cell structural integrity. Incubation of the HepG-2 cells with different concentrations of CCIN suspension did not result in significant variation in the mean absorbance. MTT assay showed reduced cytotoxicity of epirubicin-loaded CCIN in HepG2 cells as compared with that of epirubicin alone. The cell growth inhibition rate was significantly higher with epirubicin-CCIN mixture that contained a lower proportion of CCIN. In acute toxicity experiment with mice, the median lethal dose (LD(50)) of epirubicin was 16.9 mg/kg, while that of epirubicin-CCIN mixture was 20.7 mg/kg.

CONCLUSIONCCIN uptake by HepG-2 cells does not cause obvious cytotoxicity in vitro within a certain concentration range, epirubicin-loaded CCIN has reduced cytotoxicity against HepG2 cells as compared with epirubicin, and the cytotoxicity of the mixture decreases with the increase in the CCIN content in the mixture. Epirubicin delivery in mixture with CCIN can reduce its acute toxicity in mice.