| Polymer materials are widely used in biomedical fields,due to their superior mechanical properties and processing performance.However,when these devices contact with blood or living tissue,blood coagulation,inflammation and rejection occur,restricting the clinical application of polymer materials currently.Phosphorylcholine(PC)is a common zwitterion and can suppress non-specific protein adsorption and platelet adhesion for its excellent biocompatibility.Physical coating and photo-grafting are two of the most facile and efficient way to modify the biomaterial surfaces.The hydrophobic groups of the MPC copolymer coatings,deposited by physical coating method,would migrate to the surface after stored in air for a long time or heated for hours,leading to the biocompatibility performance of the zwitterionic coating seriously declined.Therefore,the researchers are committed to improve the anti-fouling performance and interfacial stability of coatings.In this thesis,the swelling-anchoring and photochemical methods were used to improve the anti-biofouling performance and interfacial stability of MPC copolymer coatings.The main works are as follows.(1)A stable zwitterionic surface was fabricated by a simple swelling-anchoring method with phosphorylcholine-based amphiphilic copolymer(PMC)containing rigid hydrophobic cholesteryl side group.The phosphorylcholine-based amphiphilic copolymer(PML)containing flexible alkyl side group was used as control.The influence of types of swelling solvents,swelling time and dip-coating time on the hydrophilicity of the modified polycarbonate plate was studied.The results showed that the optimal hydrophilicity could be achieved under the following conditions:acetone as swelling agent,5 s of swelling time,0.2 wt%of amphiphilic copolymer and 2 h of dip-coating time.XPS test results show that the surface N and P contents of the coating surface were 2.50%and 2.72%respectively.When the coating was heated at 100 ℃ for 2h or stored in the air for 2 months,the contact angle had no changes.After the coating was soaked in 75%ethanol for 6 h or sonicated in 1%SDS for 15 min,although the contact angle increased,s-PMC-PC has still relatively better surface stability and improved interfacial stability.The Fg and BSA protein adsorption on the s-PMC-PC surface have been reduced by 91.5%and 91.5%respectively.(2)Two series of photoreactive zwitterionic polymers(PMA and PMCA)containing the hydrophilic phosphorylcholine(MPC),the photoactive aromatic azide(AZMA),and/or the hydrophobic cholesterol(CholMA)were synthesized and deposited on polypropylene plate to improve its hydrophilicity.The composition of these polymer had great effect on the stability and anti-biofouling properties of the coating.The results show that the photoreactive phosphorylcholine-based random copolymer PMA and PMCA both have ultraviolet absorption at around 270 nm.When the polymer coating with a thickness of 200 nm and the illumination time of 240 s,the coating tended to be more hydrophilic and have better stability.The hydrophilic coating with more photoactive aromatic azide showed better stability.When heated at 100 ℃ for 2h,stored in air for 2 months,soaked in 75%ethanol for 6 h or sonicated in 1%SDS for 15 min,the contact angle remained unchanged.The characterization results indicated that PMCChA-PP has better surface stability and improved interfacial stability and would provide a promising way to improve the biocompatibility of the long-term blood-contacting biomaterials.And the Fg and BSA protein adsorption on the modified PP surface have been reduced by 96%and 91%respectively.(3)A series of quaternary random copolymer(PMCChA)containing both bactericidal carboxylic acid betaine group and antibacterial phosphorylcholine group was designed and synthesized.These polymers were used to modify the polypropylene plate.The effect of polymer composition on the anti-biofouling properties of the coating was systematically studied.The results showed that The hydrophilic coating with more phosphorylcholine showed better suppressed the adsorption of proteins and the adhesion of platelets marvelously,suggesting their blood compatibility improved significantly. |
