Abstract:

Objective To study the cytotoxicity of SiO₂ nanoparticles (NPs) on the liver HL-7702 cells,and to clarify its mechanism. Methods The in vitro cultured human normal liver HL-7702 cells were randomly divided into control group and 12.5,25.0,50.0,100.0 mg·L^-1 SiO₂ groups,respectively.Transmission electron microscope (TEM) was used to characterize the SiO₂ NPs,and dynamic light scattering(DLS) method was used to analyze the particle size of SiO₂ NPs.After 24 h exposure,the morphology of HL-7702 cells were observed by HE staining;MTT assay was used to determine the viability of HL-7702 cells;lactate dehydrogenase (LDH) release assay was used to detect the LDH activity in culture medium of HL-7702 cells;flow cytometry (FCM) was applied to examine the level of intracellular reactive oxygen species (ROS). Results The TEM results showed that the SiO₂ NPs were spherical,universally sized and more or less dispersed well,and the average particle size of SiO₂ NPs were (65.87±9.02) nm.The DLS method results manifested that the SiO₂ particle sizes of the SiO₂ NPs were (124.57±8.02) nm in high purity water and (139.32±9.93) nm in RPMI-1640 solution.The HE staining results revealed that the SiO₂ NPs could cause the morphological changes of HL-7702 cells,and the number of HL-7702 cells was reduced and the arrangement was disorder in 25.0 and 50.0 mg·L^-1 SiO₂ groups;in 100.0 mg·L^-1 SiO₂ group,the cells were shrunken and sparse,and part of the cells appeared the morphological features of apoptosis.Compared with control group,the cell viabilities in different concentrations of SiO₂ groups were decreased,especialy in 50.0 and 100.0 mg·L^-1 SiO₂ groups (P<0.05),while the LDH activities in culture medium and the intracellular ROS levels in 50.0 and 100.0 mg·L^-1 SiO₂ groups were increased (P<0.05). Conclusion SiO₂ NPs could cause the cytotoxicity on the HL-7702 cells in a concentration-dependent manner,and the cytotoxicity may be associated with the generation of intracellular ROS.

Key words: SiO₂ nanoparticles, HL-7702 cells, cytotoxicity, reactive oxygen species