摘要Objective This study aims to investigate and compare the toxic effects of four types of metal oxide (ZnO,TiO2,SiO2,and Al2O3) nanoparticles with similar primary size (～20 nm) on human fetal lung fibroblasts (HFL1) in vitro.Methods The HFL1 cells were exposed to the nanoparticles,and toxic effects were analyzed by using MTT assay,cellular morphology observation and Hoechst 33 258 staining.Results The results show that the four types of metal oxide nanoparticles lead to cellular mitochondrial dysfunction,morphological modifications and apoptosis at the concentration range of 0.25-1.50 mg/mL and the toxic effects are obviously displayed in dose-dependent manner.ZnO is the most toxic nanomaterials followed by TiO2,SiO2,and Al2O3 nanoparticles in a descending order.Conclusion The results highlight the differential cytotoxicity associated with exposure to ZnO,TiO2,SiO2,and Al2O3 nanoparticles,and suggest an extreme attention to safety utilization of these nanomaterials.