Research On Biological Effects Of Multi-scale Titanium Dioxide Nano-particles

Nano-titanium dioxide (Titanium Dioxide,TiO₂) is widely used in paints,paper coatings,plastics,elastomers,cosmetics,sunscreen and other supplies.Application of nano-titanium dioxide has been extended to other areas,such as ultrafine particles, electronic materials,denitriding catalyst,photoelectrocatalyst and so on.Therefore,the nano-TiO₂ shows immense market prospects,and has been thought highly of at home and abroad.TiO₂ has been considered as hypotoxic dust in the past,in many toxicological studies about dust,TiO₂ is often used as a non-toxic dust control.However,the studies find that ultrafine TiO₂ (average diameter of 60nm)-induced rat lung inflammation is even more serious than micro-TiO₂ (average diameter of 250nm) which has the same air quality concentrations.The report has changed people's awareness of the problem of particle toxicity,even non-toxic or hypotoxic fine particulate material,its ultrafine particles may also become toxic.Because of the unique physical and chemical properties of TiO₂ nanoparticles,it is difficult to use conventional methods and means of detection.After nano-TiO₂ entering the cells,the scavenging capacity of cells will decrease as the size of the TiO₂ particles shrinks,and it will result in the damage of cell membrane,changes of cell ultrastructure,fracture of nuclear DNA,and changes of protein content and enzyme activity,so it is necessary to study its biological effects and toxic effects.In this study,fine different scales of TiO₂ nanoparticles and TiO₂ microparticles are selected as research objects which are widely applied.Human keratinocytes (HaCaT),pulmonary epithelial cells (A549) and mouse monocyte macrophages (RAW) are used as the model.This research has explored the biological effects of TiO₂ nanoparticles from the conditions of depolymerization,whether entering the cells or not,the way of entering cells,the damage to cells,and the impact on DNA synthesis.According to the unique nature of nanoparticles,the influence of nano-TiO₂ on cell ultrastructure in vitio,biochemical indicator and pathological changes are studied systematically in this article.The dose effect, time effect and size effect between nano-TiO₂ and cells are also discussed in detail.This article has still made a further study about the influence of TiO₂ nanoparticles on DNA synthesis,and has established and developed test methods and experimental techniques about biological effects and toxicology of nano-matericals.The results are as follows: 1. The depolymerization and dispersion of five different scales of TiO₂ nanoparticles and TiO₂ microparticles show good under the conditions of the power at 300W,the temperature around 25℃and the ultrasound about 30min .2. Five different scales of TiO₂ nanoparticles and TiO₂ microparticles can enter cells,and can maintain a good dispersibility and stability after entering. The volume of TiO₂ nanoparticles in the cells is related to its concentration, scale and the time that it enters cells.3. Compared to silicon dioxide (SiO₂) and four three iron oxide (Fe3O4) nanoparticles,TiO₂ nanoparticles mainly enter cells by way of phagocytosis, combining the may of the direct rupture of membrane,while the SiO₂ nanoparticles enter cells by the two ways .4. The damage of TiO₂ nanoparticles and TiO₂ microparticles on the cell ultrastructure was related to its dose .5. The impact of TiO₂ nanoparticles on cytoskeletal filament shows a dose– effect Relationship at a certain concentration range.6. TiO₂ nanoparticles caused cells to produce reactive oxygen species and made n the cells oxidative damage. MDA content which TiO₂ nanoparticles induced cells to produce and TiO₂ nano-particle concentration shows a dose - response relationship.7. The impact of TiO₂ nanoparticles and TiO₂ microparticles on cell viability shows a dose-effect relationship, but its size there were no significant differences.8. The inhibiton of TiO₂ nanoparticles on the DNA synthesis is closely related to its dose and particle size.