Study On In Vivo Biological Toxicology Of Titanium Dioxide Nanoparticles

Nano-sized TiO₂ began to be manufactured in the late 80s' of the 20th century.Because of its unique optical and electrical properties,nano-sized TiO₂ is widely used as catalyst,UV absorber,gas sensors and in many other areas.With the development of nanotechnology,however,nano-materials contacting with humans becomes more frequent,and would directly enter human bodies during production and use or through the environment and food chains.People are now very concerned about their potential negative effects.The present study used nano-sized TiO₂ as the research object and mice(CD-1(?)(ICR)) and zebrafish(Danio rerio) as the exposure objects to investigate the biotoxicological effects of nano-sized TiO₂.The underlying mechanism was preliminarily discussed.The nano-sized TiO₂ used in the experiment was anatase with a uniform particle size distribution and a large specific surface area.Mice were exposed to different doses of nano-TiO₂(0,324,648,972,1296,1944,2592 mg kg^-1) for 14 d via intraperitioneal injection to test the acute toxicity.Blood samples were collected via the ocular vein,and mice were sacrificed through cervical dislocation method at 0,1,2,7,and 14 d,respectively.Blood biochemical parameters(ALP,ALT,AST,BUN) were measured to examine the liver and kidney functions.Aquatic species zebrafish were exposed to nano-TiO₂ particles in five different concentrations(1.0,2.0,4.0,5.0,7.0 mg L^-1) to test the chronic exposure effect.The physiological indicators(organs weight ratio) were measured and the growth situation was record.Titanium contents in tissues of both mice and zebrafish were detected by ICP-MS to study the TiO₂ accumulation and distribution in vivo.The histology of these tissues was also examined.The results demonstrated that during exposure, nano-sized TiO₂ had a certain growth inhibition on both mice and zebrafish. Nano-TiO₂ led to blood biochemical parameters deviating from their normal values in mice and affected the normal functions of liver and kidney. Titanium was detected in liver,spleen,lung,kidney of mice,and in heart, liver,gill and brain of zebrafish.Through chronic exposure,nano-TiO₂ was capable of moving through the blood-brain barrier and the blood-heart barrier of zebrafish,and then reached and accumulated in tissues.Moreover, nano-TiO₂ transported between various organs.It was indicated through histopathological examinations that nano-TiO₂ resulted in significant inflammation and pathological changes in tissues,thereby causing certain tissue lesions.