Quantification of F2-isoprostane isomers in cultured human lung epithelial cells after silica oxide and metal oxide nanoparticle treatment by liquid chromatography/tandem mass spectrometry

F₂-isoprostanes are lipid peroxidation products of arachidonic acid in cell membrane and are reliable biomarkers for oxidative stress and cell membrane damage. Nanomaterials are widely used as raw materials in many industries and will have high potentials to be used in life science and medical fields. However, the human health impact of nanoparticles has caused people's great concern. Unfortunately, the mechanisms of cytotoxicity of many nanoparticles are not well defined. By measuring the levels of F₂-isoprostane isomers in cultured cells after nanoparticle exposure, the information can be used to explain whether the cytotoxicity of nanoparticles is caused by lipid peroxidation and to investigate the biological pathways. In this study, a liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed to separate and quantify F₂-isoprostane isomers in nanoparticle-treated human lung cancer cells. Silica oxide (15 nm) and other four metal oxide nanoparticles including Fe₂O₃ (30 nm), Al₂O₃ (13 nm), TiO₂ (40 nm) and ZnO (70 nm) are chosen in this study. The isotope forms of F₂-isoprostane isomers, 8-iso-PGF_2α-d₄ and PGF_2α-d₄, were used as internal standard (IS). After human lung epithelial cells were exposed to different nanoparticles for 24 h, F₂-isoprostanes were extracted by a single step solid phase extraction with Oasis HLB cartridge. For the first time, six F₂-isoprostane isomers were tentatively identified and quantified in human lung epithelial cells. The levels of F₂-isoprostane isomers in the cells increased after the treatment with nanoparticles. For SiO₂, Fe₂O₃, and ZnO nanoparticles, F₂-isoprostane isomers increasing are consistent with nanoparticles’ cytotoxicity data. For Al₂O₃ and TiO₂ nanoparticles, F₂-isoprostane isomers levels increased even before nanoparticles showed significant cytotoxicity at 100 μg/mL concentration in 24 h. Based on our best knowledge, this is the first study on the F₂-isoprostane isomers corresponding to nanoparticles’ exposure in vitro. Our study demonstrates that SiO₂ (15 nm) nanoparticle showed the highest degree of lipid peroxidation and cell membrane damage among the studied nanoparticles.