Development Of Functionalized Nanomaterials As Actinide Decontamination And Decorporation Agents

Actinides play a decisive role in national defense and nuclear industry,however,the radioactivity and chemical toxicity of actinides raise concerns of their potential threaten to the public health.Currently,for the contamination of actinides to human body,the most efficient treatment method is to use chelating agent to coordinate with actinides,which can effectively reduce the deposition of actinides and the damage caused by radiation exposure as much as possible.The pharmaceutical agents used for skin decontamination and in vivo decorporation are called decontamination and decorporation agents,respectively.In this dissertation,from the perspective of coordination chemistry,we rationally designed and prepared novel chelating materials to overcome the current disadvantages of those agents.The main ideas and conclusions are as follows:(1)Currently,there is a limited selection of uranium decontamination agents which suffer from disadvantages such as insufficient decontamination effect,readily transdermal permeation of the residue and untimely effect feedback.Herein,we propose the idea of “aggregation induced absorption preventing + real-time monitor”.By grafting 3,2-hydroxypyridinone(HOPO),which exhibits strong affinity for uranium,onto fluorescent carbon quantum dots(CQDs),blue fluorescent CQDs-HOPO with particle size of 2-4 nm were obtained.Then the decontamination,absorption inhibition and monitoring efficacies of CQDs-HOPO were evaluated by simulated skin decontamination experiments.Results show that the CQDs-HOPO can not only effectively remove uranium from the skin,but also form aggregates with the size of about 60-160 nm rapidly after complexing with uranium,which is hard to be absorbed by transdermal.In addition,the fluorescence quenching induced by the aggregation of CQDs-HOPO is directly correlated with the uranium concentration.Therefore,the uranium decontamination progress could be evaluated by monitoring the fluorescence intensity of the decontamination solution.(2)The current reported actinide decorporation agents,including molecular ligands and functional nanomaterials,still have some limitations.Firstly,the current research generally focuses on the decontamination effect of a single nuclide,and decorporation of multiple nuclides has barely been considered and evaluated.Secondly,few research has been reported on the radiation protection effect regarding the oxidative stress induced by internal exposure of actinides.Herein,we propose a new strategy of “co-decorporation + radiation protection”.Melanin was chosen since it contains both metal chelating unit and radical quenching moiety.Then polyethylene glycol modified melanin nanoparticles(MNPs-PEG)were synthesized and the co-decorporation and radiation protection performance of U(VI)and Th(IV)were investigated.In vitro experiments results indicate that MNPs-PEG can selectively adsorption more than 99% of U and Th in the presence of excessive interference ions,and have excellent radical quenching ability.In vivo study demonstrates that MNPs-PEG can effectively reduce the deposition of uranium and thorium in mice simultaneously.In addition,ROS level assays show that MNPs-PEG can almost completely scavenge radiation-induced ROS in cells.The experimental results reveal clear advantages of MNPs-PEG in terms of co-decorporation and radiation protection effect compared with existing decorporation agents.