The Study Of New Radical Scavenging Material

Reactive oxygen species(ROS)refers to a specific type of oxygen-containing chemically active substance.For organisms,it has positive effects such as promotion of cell proliferation and differentiation and resistance to pathogenic microorganisms;however,the excess of reactive oxygen species can lead to oxidative stress(referring to the imbalance of oxidation and antioxidation in the body and causing aging and disease in human).Free radical scavengers or antioxidants are the key to solving this problem.Gel permeation chromatography(GPC),Nuclear magnetic resonance(NMR),Dynamic light scattering(DLS),Fluorescence spectrophotometer and UV-Visible spectrophotometer(UV-vis)were used in the experiment to characterize and confirm the molecular weight and structure,particle size of micelles,critical micelle concentration(CMC)and the performance of capturing free radicals.The main results are as follows,(1)Two types of polymers based on dopamine(DOPA)are synthesized using poly(ethylene glycol)methyl ether methacrylate and poly(acrylic acid)as raw materials.In the first reaction route,the polymer P[DOPA-OE]is synthesized through the protection of DOPA’s hydroxyl monomer preparation,reversible addition-fragmentation chain transfer(RAFT)polymerization and the reaction of deprotection.In the second reaction route,the polymer P[DOPA-AA]is synthesized through the amidation between DOPA and poly(acrylic acid).The results show that the structures of P[DOPA-OE]and P[DOPA-AA]are correct;P[DOPA-OE]is thermosensitive can form micelle in aqueous solution and can quench hydroxyl radicals completely;P[DOPA-AA]cannot form micelle in aqueous solution,but it still has good performance in scavenging radicals.(2)Starting from the classic antioxidant BHT,the polymer P[HEMA(BHT)-OE]is synthesized using 3,5-Di-tert-butyl-4-hydroxybenzoic acid(BHTA)as raw material.Two reaction routes are tried.In the first route,the target macromolecule is synthesized by two steps which the monomer is synthesized by esterification firstly and then copolymerizes with OE;in the second route,the random copolymer P[HEMA-OE]is synthesized by free radical polymerization,then the macromolecule radical scavenger based on BHT is synthesized by the esterification.Results indicate that the polymer obtained by the first route can form micelle in aqueous solution,but the test of scavenging free radical show ineffective.This is probably due to the destruction of the phenolic hydroxyl of BHT during the polymerization process;the polymer P[HEMA(BHT)-OE]got by the second route is thermosensitive and amphiphilic,it can form micelle in aqueous solution and capture hydroxyl radicals from Fenton reaction,DPPH experiment indicates that the polymer could quench radicals in both the water phase and the oil phase.