Evaluation Of Respiratory Toxicity Of Cerium Oxide Nanoparticles Via Intrarachael Instillation In Mice

With the widespread application of the nanotechnology, more and more nanomaterialswere used into industries, pharmaceuties, biotechnology and etc. As for the novel propertiesof cerium oxide nanoparticles (nano-ceria), they, regarded as a kind of functional materials,were widely used in catalysts, fuel cell, functional ceramics, new glass materials and etc. Inthe application of fuel additives, nano-ceria can improve the combustion efficiency, saveenergy and reduce emission of hydrocarbons and particles. However, a growing number ofnano-ceria were released into the air unfortunately, whose impact on environment and humanhealth has caused a wide public concern. Some studies found that, the biological effect ofnano-ceria is closely relative to its own physical and chemical properties like particle size,morphology, surface charge and etc. For comprehensive evaluation of respiratory toxicity ofnano-ceria and understanding the effects of particle size and morphology on the pulmonarytoxicity, in this study we have chosen four nano-ceria with different particle sizes andmorphology (two kind of ceria with3-5nm including Ceria-p and Ceria-h,25nm CeO2, andRod CeO2), and used CD-1(ICR) mice as animal model, and then observed the change of therelative biochemical indexs in the lung of mice at different time points (the1,3,7,28day),and respectively studied and discussed the pulmonary toxicity of two kinds of nano-ceria inthe same sizes, and the pulmonary toxicity of nano-ceria with different sizes and morphology.The results showed that the particle size, morphology, the size and shape of agglomerationand their surface chemical properties are very important factors which affect the pulmonarytoxicity of nano-ceria. Generally speaking, chemical properties of nanomaterials is the majorfactors in the toxicity of nano-ceria with the same size. Because of the ROS generation,Ceria-h exposure caused two waves of lung injury: BAL inflammation and cytotoxicityinduced by particle overload in the early stage, and pulmonary lipid peroxidation andpro-inflammation in the latter stage. Unlike the Ceria-h, Ceria-p caused a more potentparticle-overload inflammation at the early stage of exposure. Since the intratrachealinstillation of Ceria-h caused a more persistent lung injury compared to Ceria-p, the long-termpulmonary and systemic toxicity of Ceria-h needs further study. On the other hand,3-5nm CeO2has a stronger toxicity effect than25nm and Rod CeO2in the early stage (the day1to7); but in the late exposure, compared with3-5nm CeO2,25nm and Rod CeO2can causemore intense pulmonary lipid peroxidation; however, the toxicity mechanism need to bestudied further.