Safety Evaluation Of Titanium Dioxide Nanoparticles In Vitro And In Vivo

Titanium dioxides（TiO₂）are widely used mineral nanoparticles,which can be applied as pigments,preservatives,packaging materials and food additives.Generally,TiO₂ food additive contains up to 36% particles with particle size less than 100 nm,namely TiO₂ nanoparticle.According to the physical characteristics,TiO₂ nanoparticles with smaller size have better colors,tastes and antiseptic properties.Fullerenols nanoparticles,as the wide used carbon nanomaterials,have also been developed for new sweeteners and carrier into food and medicines.With the development of nanotechnology and food science,human have more opportunities exposed with TiO₂ nanoparticles.However,there are no definitive conclusions about the risks of TiO₂ nanoparticles.Therefore,it is necessary and important to study the safety of TiO₂ and fullerenol nanoparticles in oral.In vitro,Caco-2 gut epithelial cell line was selected as the model to investigate the oral safety of TiO₂ and fullerenol nanoparticles.The viability,proliferation,apoptosis and DNA damage of Caco-2 cells were investigated after the Caco-2 cells were treated with the TiO₂ and fullerenol nanoparticles under the concentrations of 50,100,200 and 500 mg/mL.The results showed that both TiO₂ and fullerenol nanoparticles have no significant effects on cellar viability,proliferation and apoptosis.In addition,TiO₂ nanoparticles with 50 and 100 mg/m L caused Caco-2 gut epithelial cell apoptosis,while fullerenol nanoparticles induce cell apoptosis at the concentrations of 200 and 500 mg/mL.Maybe the bio-effects of TiO₂ nanoparticles were different with fullerenols mainly because of the different agglomeration degree of two kinds of nanoparticles measured by Scanning Electron Microscope（SEM）and Dynamic Light Scattering（DLS）.Based on the experiments in vitro,it is found that the unstable bio-effects of TiO₂ nanoparticles were affected by the physicochemical properties.Further,the normal C57 mice model with oral administration was used to evaluate the oral safety of anatase and rutile nanoparticles in vivo.The C57 mice were gavage with 50 mg/kg/day for 28 days,then dissected the mice.The Hematoxylin-Eosin（HE）results showed that the anatase and rutile nanoparticles were not affected to liver,spleen,kidney,lung and brain.While the anatase nanoparticles can cause the wall of small intestinal thickening and the rutile nanoparticles can caused the disorder of intestinal cell.Inductively Coupled Plasma Mass Spectrometry（ICP-MS）were used to detected the bio-distributions in the mice and the results showed that the Ti contents in spleen of mice fed with anatase nanoparticles increased significantly and the Ti contents in lung of mice fed with rutile nanoparticles increased significantly compared with the anatase group.The content of Ti in the feces of mice fed with both anatase and rutile were much higher than that in the control group.The result indicated that most of the TiO₂ nanoparticles can be excreted through the feces,but only a few of them remained in mice,which caused some damage to the small intestine and large intestine of C57 mice.