In vitro study of silica nanoparticle-induced cytotoxicity based on real-time cell electronic sensing system

The biological fate and potential toxicity of nanoparticles have become hot topics since the use of nanoparticles was extended to the biomedical and biotechnological field. In this paper, an in vitro study of silica (SiO2) nanoparticle-induced cytotoxicity was presented mainly by real-time cell electronic sensing (RT-CES) system, which could be used for label-free, dynamic measurement of cell responses to cytotoxicants. The cytotoxicity of both 20-nm silica nanoparticles and microscale SiO2 powder in cultured RAW264.7 cells at dosage levels from 31.25 to 8000 microg/ml was evaluated comparatively. The experimental results showed that the cell index (CI) decrease induced by SiO2 nanoparticles appeared earlier than that by the microscale SiO2 powder at the same dose. The nanoparticles in the dose of 500 micdrog/ml had the toxic effect by the Cell Index Curves of RT-CES, while the microscale SiO2 powders in the same dose did not show obvious effect. The above experimental results were compared with the experiments of a tetrazolium compound-based colorimetric method (MTT assay) and LDH activity in medium. The results showed that the RT-CES assay displayed equal sensitivity and correlation to MTT assay. LDH activity caused by SiO2 nanoparticles at dose of 250 and 500 microg/ml was higher than that by microscale SiO2 particles, which indicated that the exposure to SiO2 nanoparticles could result in a dose-dependent cytotoxicity in cultured RAW264.7 cells due to cell membrane injury. The RT-CES system allows a realtime, continuous monitoring and quantitative recording of the whole assay process and provides a new insight into the cell-toxicant interaction.