Cell membrane injury induced by silica nanoparticles in mouse macrophage.

Studies on the cytotoxic mechanism of SiO2 nanoparticles is of vital importance for estimating the potential risk of overexposure and cytotoxicity amelioration and safety precautions of SiO2 nanoparticles. The cell membrane injury induced by 20-nm silica nanoparticles was investigated by measuring reactive oxygen species (ROS), membrane fluidity and free Ca2+ content ([Ca2+]i) in cells with laser scanning confocal microscope (LSCM). The 20-nm SiO2 nanoparticles at different concentrations of 31.25, 125, and 500 microg/ml were respectively incubated with RAW264.7 cells for 24 h to determine oxidative stress responses, membrane fluidity, intracellular [Ca2+]i concentration. Exposure to SiO2 nanoparticles at 125 and 500 microg/ml increased ROS levels and intracellular [Ca2+]i, reduced membrane fluidity levels. The decrease of the membrane fluidity indicated membrane damage. Increases of ROS generation and intracellular [Ca2+]i played a role in cytotoxicity. Results showed that mechanisms of cytotoxicity induced by SiO2 nanoparticles was closely correlated to increase oxidative stress, decrease membrane fluidity and perturbation of intracellular calcium homeostasis.