| With the rapid development of economy and aggravated degradation of environment,characteristics of air pollution in China tend to be obvious.It is not only reflected in various sources list of atmospheric pollution,but also presented in complex pollutants.Effects of atmospheric particulate matter(PM)on human health radually become a focus of research and public attention.Increasing researches are in view of the toxicity of PM compounds in atmosphere,however,less of them aim at toxicity and mechanism of mineral particles in the atmosphere system.In this study,the common atmospheric mineral dusts,such as quartz,calcite,montmorillonite,sericite and albite,as well as the mixed mineral dusts and heavy metal pickled mineral dusts are the main research objects of research.The oxidative damage of single-phase mineral dust on A549 cells,and the influence of mineral dusts and heavy metal pickled mineral dusts on microenvironment of A549 cell membrane were analyzed.The joint damage effect and mechanism of various mineral phases and heavy metal pickled mineral dusts on A549 cell were relvealed.The main contributions of this dissertation aredescribed as follows:1.Characteristics of single,mixed and heavy metal pickled mineral dustsBased on the most common mineral phases and heavy metal ions in PM,the single,mixed and heavy metal pickled mineral dusts were preparaed.Their chemical composition,phases,morphology and surface functional groups were characterized using XRF,XRD,SEM,FTIR;surface electrical potentials were analyzed by a Zeta potential analyzer;dissoloved ionsfrom the mineral dusts were analyzed using ICP;the results show that surface electrical potential of mineral dusts is correlated with lattice replacement,broken bonds,octahedral dissociation,as well as H+,Ca2+,Mg+ and OH-,SO42-,etc in solutions,and that further influence the activity sites of hydroxyl on surface of mineral dusts.2.Reactive oxygen species(ROS)and oxidative damage in A549 cells induced by single-phase mineral dustsThe viability of A549 cells,ROS both transient and in stable liquid environment,and intracellular enzyme activities were teated by biochemical methods.Results indicate that effect of mineral dusts with similar particle size on cell metabolism and proliferation inhibition follows as:montmorillonite>>sericite? quartz>feldspar>calcite;the release rule of hydroxyl radical(·OH)by mineral dust and changes of intracellular and extracellular H2O2 of A549 cell are controlled by mineral composition(SiO2 and Fe2O3),crystal structure,broken bonds and fracture surface,as well as unsaturated ions,hydrated surface and active functional groups;mineral dusts caused accumulation of ROS and reduction of glutathione(GSH)in A549 cells,and induced fluctuations of superoxide dismutase(SOD);oxidative damage caused by mineral dust is a reason which lead to the reduction of cell viability and cell apoptosis.3.Influences of mixed dusts on membrane bound microenvironment of A549 cellsTaking calcite/quartz mixed mineral dusts as the main object of research,through a systematic research on the released free radicals,the change of dissolved ions,intracellular and extracellular pH,membrane oxidation state and potential,the study showed that calcite in mixed dusts changed the efficiency of ion leaching from quartz.During the interaction between dusts and cells,a slightly alkaline buffer interface "H+-HCO3--CO32--Ca2+" was formed on the surface of calcite dust,and ?Si-O-Ca+ ligands were formed on the surface of siliceous dust;the interaction between quartz and calcite mitigated the change of pH and mechanical stimulation of dust on A549 cells;calcite/quartz dust caused the increase of[Ca2+]i in A549 cells,which was not related to the extracellular Ca2+;antagonism and synergy effect of ROS in A549 cells induced by calcite/quartz dusts are affected by total concentration of dust;and with the increaseing dose of silica,the polarization of cell membrane was enhanced,ROS elevated,however,calcite powders significantly reduced the polarization effect of cell membrane,abated the level of intracellular ROS;combined effect among different diverse dusts are different,of which are closely related to the mineral properties.4.Membrane damage of A549 cells induced by heavy metal pickled mineral dustsThrough the analysis the metabolism ability,intracellular ROS,mitochondrial membrane potential(MMP)and intracellular calcium ions([Ca2+]i)of A549 cells after treated by heavy metal pickled mineral dusts,the research aims to reveal the combination effects of heavy metals and dusts,and explore the active sites between heavy metal pickeld dust and cell membrane and finally reveal the damage mechanism.Results showed that heavy metal pickled quartz and calcite dust both induced the increase of ROS,MMP in A549 cells,and inhibited cell proliferation;heavy metals and quartz or calcite dust show synergistic inhibition effects to A549 cells,while control by the bonding state of heavy metal ions on the dust's surface;the exchangeable heavy metal ions and mineral dust show synergistic toxic to A549 cells,while metal ions bonded to carbonates present antagonism effect with mineral dust;heavy metal on the surface of dust is laible to bond with molecules of cell membrane which leading to higher[Ca2+]i;however,the enhancement of fluorescence was varied at different parts of cells after treated by different heavy metal ions.5.Micro-mechanism of cell membrane damage induced by mineral dustThe interactions between mineral dust and protein,phospholipid and other major membrane molecular were studied using 3-D fluorescence,infrared and Raman spectroscopy.Results showed that electrostatic attraction effect occured between positive charge on mineral dust,heavy metal pickled mineral dust and negative charge on the surface of cell membrane,such as carboxyl,phosphoryl phosphate groups(PO43-),while silicon and silicon free radicals that bearing negative charges can bond with the amine(ammonium)on cell membrane;the interaction caused vibration change in phosphoryl group in cell membrane phospholipids,and change of secondary structure of protein;free radical released by mineral dust is also contributed to the membrane damage,which ultimately leading to disfunction and structure damage of A549 cells. |
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