title: Cytotoxicity and DNA damage in mouse macrophages exposed to silica nanoparticles.
abstract: Silica (SiO2) nanoparticles are being progressively applied in various applications, including cosmetics, food technology, and medical diagnostics. Although crystalline SiO2is a known carcinogen, the carcinogenicity of SiO2nanoparticles remains unclear. Here, we assessed the cytotoxic effects and DNA injury induced by exposure to various dosages of SiO2nanoparticles at 0-2400 mg/mL (0-3200 mg/mL microscale SiO2as positive control) for 24 h using RAW264.7 cells, followed by methyl tetrazolium (MTT) assay. Cells were also treated by 31.25, 125, and 500 mg/mL SiO2nanoparticles (500 mg/mL microscale SiO2as positive control) for 24 h and examined by single cell gel electrophoresis assay (SCEG) and flow cytometry. Outstanding dose-related decline in cell viability was observed with enhancing dosages of SiO2nanoparticles by MTT assay. The inhibitory concentration 50% of SiO2nanoparticles and microscale SiO2was 16690 and 5080 mg/mL, respectively. The comet rate (comet%), length of tail, the percentage in DNA tail (TDNA%) and olive tail moment (OTM) induced by SiO2nanoparticles were significantly increased in comparison with control and microscale SiO2at 500 mg/mL. 500 mg/mL SiO2nanoparticles and microscale SiO2caused a significant increase in apoptosis rate, decreased proliferation index and increased cell proportions in G0/G1phases by contrast to the negative control (P < 0.05). This indicates that SiO2nanoparticles are more cytotoxic than microscale SiO2particles; they induce DNA injury, increase apoptosis, and decrease the proliferation index in RAW264.7 cells. DNA injury and apoptosis may be involved in reducing cell proliferation.
authors.affiliation: Key Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, China yanghongr@seu.edu.cn.
authors.forename: H
authors.initials: H
authors.lastname: Yang
authors.affiliation: Key Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, China.|School of Public Health, Xuzhou Medical College, Xuzhou, China.
authors.forename: Q Y
authors.initials: QY
authors.lastname: Wu
authors.affiliation: Key Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, China.
authors.forename: C S
authors.initials: CS
authors.lastname: Lao
authors.affiliation: Key Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, China.
authors.forename: M Y
authors.initials: MY
authors.lastname: Li
authors.affiliation: Key Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Key Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: School of Medicine, Southeast University, Nanjing, China.
authors.forename: B
authors.initials: B
authors.lastname: Shi
mesh_terms: D000818:Animals; D017209:Apoptosis; D059447:Cell Cycle Checkpoints; D002470:Cell Survival / Q000187:drug effects; D053904:DNA Breaks, Single-Stranded; D004249:DNA Damage; D051379:Mice; D053758:Nanoparticles / Q000633:toxicity*; D000067996:RAW 264.7 Cells; D012822:Silicon Dioxide / Q000633:toxicity*
chemical_list: D012822:Silicon Dioxide