Reactive Oxygen Species(Ros)Responsive Selenium/Tellurium-Containing Assemblies

Stimuli-responsive polymers are defined as polymers which could response to environmental change and undergo structural or qualitative changes.As a result,external chemical or biochemical signals could be transformed as light,heat or mechanical force,vice versa.To further reveal the secrets of organisms,it is significant to develop novel intelligent biomaterials and nanotechnology.One of the most important stimuli is reactive oxygen species(ROS).ROS,as a sort of reactive molecules or free radicals,play important roles in cell metabolism and are always related with many diseases.Recently,increasing studies on ROS responsive polymer materials are reported.However,there are still many challenges remained.The thesis is focused on three questions in the stimuli responsive material area: how to maintain the responsiveness with lower concentration of stimuli-responsive molecules,how to realize the fabrication of hierarchical responsive materials and how to develop novel responsive systems based on selenium/tellurium related organic reactions.Based on different sort of selemiun/tellurium molecules,we developed several ROS responsive assemblies.This work include three parts as shown below:(1)We developed a general coassembly method to fabricate ROS responsive systems based on the coassembly of selenium/tellurium-containing molecules and phospholipids,taking advantage of the responsiveness of selenium/telluriumcontaining molecules and the biocompatibility of phospholipids.With a small amount of selenium/tellurium-containing molecules,the system could exhibit similar responsiveness.Coassembly could also be employed as a general method to fabricate different kinds of responsive systems.(2)We copolymerized both selenium and tellurium in one polymer chain,to realize the fabrication of hierarchical ROS responsive systems.Based on the different sensitivity of selenium and tellurium in ROS response,the copolymer could realize hierarchical ROS responsiveness and the polymer could undergo a stepwise oxidation process.Besides the chemical oxidation,the stepwise oxidation process could also be realized by electrochemical methods.(3)We successfully introduced the organic selenoxide elimination reaction to polymer chemistry and developd a ROS responsive degradable selenide-containing polymer.Different from previous monoselenide-containing polymer which could only be oxidized with the change of amphiphilicity,this system could realize ROS triggered controlled depolymerization and degradation of the polymer chains.This ROS responsive oxidation-elimination reaction could also be employed in telluriumcontaining molecules,which could be utilized to develop novel ultrasensitive ROS responsive tellurium-containing polymer in future.