SO_2与CeO_2超细颗粒非均相反应产物的细胞毒性效应

大气二次细颗粒物(secondary fine particulate matters,SFPMs)是我国城市大气PM_(2.5)的主要组成部分。然而由于PM_(2.5)组成成份复杂,其毒性产生的来源并不明确。在本研究中,我们以二氧化铈(CeO_2)超细颗粒物(UFPs)为大气细矿物质颗粒模型,研究了SO_2气体在模拟大气环境中,如湿度(RH)、紫外光照(UV)和NO_2存在条件下,在CeO_2UFPs界面经多相反应生成的二次无机细颗粒物的性质及与细胞毒性的构效关系。实验通过实时高通量细胞分析系统,实时观察了CeO_2-SFPMs暴露对小鼠单核巨噬细胞(RAW264.7)增殖的影响;并进一步检测了CeO_2-SFPMs对细胞膜通透性和细胞凋亡的影响。结果表明,SO_2与CeO_2UFPs作用后可转化为硫酸盐,在有NO_2存在下转化更为明显。CeO_2-SFPMs对细胞毒性效应与其生成的环境条件相关,并具有时间效应性。RAW264.7细胞暴露于CeO_2-SFPMs 8 h,细胞增殖无明显变化;暴露8~25 h后,CeO_2-SFPMs对细胞增殖的抑制率随CeO_2@CeO_2+SO_2@CeO_2+SO_2+RH≈@CeO_2+SO_2+RH+UV@CeO_2+SO_2+RH+NO_2的顺序显著升高。CeO_2-SFPMs对Raw264.7细胞膜通透性和细胞凋亡的影响研究也证明CeO_2-SFPMs@CeO_2+SO_2+RH+NO_2产生的细胞毒性最明显。

Cytotoxicity Study of Secondary Ultrafine Particles Forming from SO2 Reaction on CeO2 Ultrafine Particles

The secondary aerosol,including secondary organic aerosol and secondary inorganic aerosol,are found as the major components in PM2.5 in megacities of China.To data,the toxic components in PM2.5 that make a contribution to adverse health effects is still unclear due to the complex composition of the fine particulate matters.In the study,we used cerium dioxide (CeO2) as aerosol mineral particle model to investigate its heterogeneous reaction with sulfur dioxide (SO2) under various simulated atmospheric conditions,such as various humidity (RH),ultraviolet (UV) irradiation and nitric dioxide (NO2) existence,which formed secondary fine particulate matter (SFPM),i.e.,CeO2-SF-PMs.The preliminary characters of CeO2-SFPMs were measured by fourier transform infrared spectroscopy (FTIR) and further the structure-cytotoxicity of the CeO2-SFPMs were investigated.The xCELLigence real time cell analysis system was used to monitor the proliferation of mouse macrophage cell line (RAW264.7) after exposure to the CeO2-SFPMs.In addition,the lactate dehydrogenase (LDH) release and apoptosis of the cells were assayed after the exposure.The data showed that SO2 could be oxidized to sulfate after interaction with CeO2 ultrafine particles under the simulated atmospheric conditions.It is noteworthy that the NO2 existence can enhance SO2 transformation.The cytotoxicity of CeO2-SFPMs is associated with their formation condition and has time-dependent manner.No significant changes of cell proliferation were found after exposure to CeO2-SFPMs for 8 h.However,after the extended 8-25 h exposure,the significant inhibition of cell proliferation was observed,which following the orders:CeO2 ＜@CeO2+ SO2 ＜@CeO2+SO2+RH ≈@CeO2+SO2+RH+UV ＜@CeO2+SO2+RH+NO2.The toxic assay by LDH and apoptosis measurements also indicate that the CeO2-SFPMs@SO2 +RH+NO2 had the most significant cytotoxicity on RAW264.7 cells.