The Mechanism Of Liver Injury Induced By Two Functionalized Multi-walled Carbon Nanotubes In KM Mice

BACKGROUND AND OBJECTIVENanomaterials have been broadly applied in a great deal of industries. Functioanlized carbon nanotubes have been regarded to be the most promising nanomaterials in bio-medicine.At the same time,CNT's damage to haman health and the environmental concerns aroused along with the mass-produce and applicationIn vitro studies found that different kinds of functionalized carbon nanotubes can affect cell structure and function,even lead to cell apoptosis and necrosis.Animal experiments showed that asbestos-like carbon nanotubes can accumulate in mice alveolus,then induced inflammation and granuloma.Single-walled carbon nanotubes can totally expelled from kidney.However,recent studies showed that 80%MWCNTs would accumulate in livers via i.v.administration.Due to their ROS generation ability, MWCNTs may cause oxidative stress to liver,and the detailed mechanisms regard to this is under investigation.To investigate and evaluate the safety and bio-responses of CNTs in bio-medicinal applications,this study chose MWCNT-COOH and MWCNT-NH₂,two different kinds of surface modifications to systemically compare and elucidate the pathology and corresponding mechanisms of mice liver injury.METHODS:1.Comparison of physico-chemical properties of MWCNT-COOH and MWCNT-NH₂1) Comparison of water-solubility of MWCNT-COOH and MWCNT-NH₂2) Comparison of dispersity of MWCNT-COOH and MWCNT-NH₂ under light microscopic level3) Comparison of electrical properties of MWCNT-COOH and MWCNT-NH₂.2.The effects of MWCNT-COOH and MWCNT-NH₂ on mice behaviors,body weights and organ coefficient1) Mice toxicity response2) Body weights comparison of mice3) Comparison of mice liver and spleen weights and organ coefficient3.Liver histopathological examination of mice1) General samples observation2) Microscopic examination4.Biochemical serum assay5.Detections of liver oxidative damage1) ROS level detection2) MDA content detection3) SOD activity detection6.The observation of MWCNT-COOH and MWCNT-NH₂ by the transmission electron microscopy1) The observation of liver by the transmission electron microscopy2) The observation of liver digestion solution by transmission electron microscopyRUSULTS:1.The dispersity of MWCNT-COOH is better than MWCNT-NH₂ in PBS;2.MWCNT-COOH and MWCNT-NH₂ had no obvious effect on mice body weight, liver weight and organ coefficient in acute experimental group,sub-chronic experimental group and long-term experimental group(P＞0.05);3.MWCNT-COOH and MWCNT-NH₂ were prominently concentrated in livers,but little concentrated in lung,spleen and kidney;4.Single-exposure is not increased with an elevated level of ROS(P＞0.05) and is not caused hepatic function and hepatic pathology obviously changes;5.ROS level of the hepatocellular was increased(P＜0.05),MDA contents was increased(P＜0.05),SOD activity was decreased(P＜0.05) compared with control in sub-chronic experiment group;6.The histopathologic changes were observed under optical,such as hepatocelluar cloudy swelling and vacuolization in sub-chronic experiment group.The content of serum ALT,AST activity of MWCNT-COOH and MWCNT-NH₂ group were significantly increased(P＜0.05 ) compared with control group;7.ROS level,MDA contents,SOD activity,histopathologic and blood biochemical indexes of MWCNT-COOH and MWCNT-NH₂ group were not significantly changed compared with control group in long-term experimental group(P＜0.05 ).CONCLUTION:1.The two functionalized carbon nanotubes had significant different distributions in the liver.MWCNT-COOH exit more than MWCNT-NH₂ in the liver;2.MWCNT-COOH and MWCNT-NH₂ did not cause acute toxicity response in acute experiment group.MWCNT-COOH and MWCNT-NH₂ did cause evident toxicity response after 15 days through tail vein injection;Three months after tail vein injection,the pathologic and functional change in the liver caused by MWCNT-COOH and MWCNT-NH₂ could be repaired;3.Compared with MWCNT-COOH,MWCNT-NH₂ had a stronger ability in reactive oxygen species and liver damage.There are direct relationships between surface modification and reactive oxygen species,MWCNT-NH₂ is more toxic than MWCNT-COOH.