Construction And Properties Of Micro-nano Interface Modified By Zwitterionic Polymer

In recent years,zwitterionic polymers have been widely used to modify various micro-nano surfaces to enhance the hydrophilicity and other properties of materials,so that they have shown great application potential in biological systems.The anti-polyelectrolyte behavior of zwitterionic polymers is caused by their molecular chains containing zwitterionic groups or mixed anionic and cationic end groups.The solvation of the zwitterionic polymer molecular brush will produce a high retention rate of solvent water and the surrounding water molecules to form a tight hydration layer,and the hydration layer also has the function of space and energy barrier,which can effectively prevent organic matter and biological entities of adsorption.In this work,the poly?betainesulfonate?-typezwitterionicpolymer,i.e.poly[N,N-dimethyl?methacrylamidopropyl?propane sulfonate ammonium]?PSPP?was grafted on the sueface of micro-nano surfaces,so that the zwitterionic polymer grafted gold nanoparticles and silica nanoparticles were constructed,meanwhile the zwitterionic polymer micropatterns on constructed on the surface of gold and glass plates.Then,the stability and biocompatibility of these nanocomposites in water have been studied.The main work and conclusions are as follows:1.Gold nanoparticles and PSPP were prepared by citric acid reduction method and atom transfer radical polymerization technology,respectively.Then the PSPP was grafted to the surface of gold nanoparticles by Au-S bond through ligand exchange method and the aggregation behavior of PSPP grafted gold nanoparticles?Au@PSPP?in aqueous solution was studied.The influence of temperature,salt,ploymer and pH on the stability of Au@PSPP.The results show that Au@PSPP has excellent thermal stability in pure aqueous solutions and salt solutions,but at different temperatures when free molecular chains are present It will show reversible aggregation phenomenon,and the presence of salt can make the surface more super-hydrophilic and less prone to aggregation.At the same time,the anion has better polarization than the cation and can effectively inhibit the aggregation of Au@PSPP.the study also found that the dispersion and aggregation state of Au@PSPP can be reversibly changed by adjusting the pH value.2.Prepare the surface initiator 2-bromo-2-methyl-N-?3-?triethoxysilyl?propyl?propanamide?BTPAm?by substitution reaction,and then graft BTPam to silica nanoparticles SiO₂@BTPAm was prepared on the surface of the particles,and finally PSPP was grafted onto the surface of SiO₂@BTPAm by surface-initiated atom transfer radical polymerization to prepare SiO₂@PSPP.The preparation of initiators,the preparation of initiator-grafted silica nanoparticles and the effects of different solvents on the thickness of polymer linking grafts during polymerization were studied,as well as their cytotoxicity.The results show that these nanocomposites have very good biocompatibility.3.Preparation of gold and glass plates with specific zwitterionic polymer molecular brush patterns through micro-contact printing and surface-initiated atom transfer radical polymerization techniques.To study the effect of initiator concentration,imprint pressure and imprint time on the pattern during micro-contact printing,the hydrophilicity,cell adsorption of the substrate with attached zwitterionic polymer were explored.