Application Of Poly(2-oxazoline) And Poly(Ethylene Glycol) For Surface Modification Of Metal Biomaterials And Biomedical Hydrogel

Poly(ethylene glycol)(PEG)and poly(2-oxazoline)(POXA),as biocompatible polymers,were been used to research novel strategies for surface modification of metal biomaterials and biomedical hydrogel in this dissertation.This dissertation is composed of five chapters.Chapter 1:The research background and progress of surface modification of metal biomaterials and biomedical hydrogel.Chapter 2:In this chapter,a novel approach of surface modification was explored to improve the biocompatibility and antifouling properties of titanium by using the PEG-o-quinone.As all know,PEG-catechol can self-assemble onto titanium surfaces easily.However,the higher grafting density by this approach is hard to be obtained.O-quinone(the oxide of catechol)as adhesive segment was the first time used to graft PEG brushes onto titanium surfaces.PEG-o-quinone grafted onto titanium surfaces by electro-assemble.A clear result is that the grafted density of electro-assembly PEG monolayers(e-AMs)can be very high,and the grafted density of e-AMs can be easily modulated.In addition,the long-term stability of biocompatibility and antifouling properties of e-AMs is excellent.Chapter 3:This chapter described using a pseudopeptide polymer,poly(2-methyl-2-oxazoline)(PMOXA),to form a bionic non-brush coating by electrochemical assembly on 316L stainless steel surface for improving biocompatibility and corrosion resistance.In order to produce stable coating,dopamine(DA)and partially hydrolysed PMOXA(PEI-co-PMOXA)were used to assemble on the surfaces of 316L stainless steel via electrochemical oxidation and Michael addition between multi-imino groups of PEI-co-PMOXA and poly(dopamine).The effect of the molecular weights and hydrolysis degree of PMOXA on formed coatings with respect to the biocompatibility and corrosion resistance of modified stent materials were studied in detail.The results showed that the coating formed by PMOXA with moderate molecular weights and hydrolysis degree possessed the excellent anti-fouling property and biocompatibility.Moreover,the migration and proliferation of Human Umbilical Vein Endothelial Cells(HUVECs)on this kind of coating were also greatly enhanced.Chapter 4:In this chapter,poly(2-oxazoline)(POXA)with double bond and thiol groups as pendant functional groups have been synthesized.The POXAs were used for UV-photo-crosslinkable sol-gel system,base on ene-thiol "click" reaction.The results showed that it is very fast for the sol-gel system to form a clear transpatent hydrogel under the UV light with 365 nm wave length.Due to the number of pendant functional groups is adjustable,the module of this hydrogel system can be adjustable as required.Chapter 5:In this chapter,Photo-cleavage hydrogel based on coumarin and POXA was explored.Two different photo-cleavable coumarin based compounds were synthesized.One is a kind of water-soluble small molecule compound,which with two maleic acid ester end groups.The other is a kind of water-soluble co-polymer with coumarin structural unit.They can form a hydrogel with thiol modified POXA.And the hydrogel was been proofed can be used to control drug release by UV light.