Synthesis Of Diblock Copolymer Coatings Via ATRP And Its Improvement For Substrates Biocompatibility

Biomaterials play a significant role in biomedical field and have been widely applied in various medical devices and therapy. With development of tissue engineering, nanotechnology and materials science/technology in recently years, new achievements in biomaterials attained. Unexpected reactions like protein adsorption and unconformation when living things contacting with materials are still obstacles of application biomaterials. Constructing of effective bio-interfaces is the objective with tremendous scientific and economic significance.Surface modification on materials with biocompatible molecular or their polymer is an effective way to obtain practical biomaterials. Atom Transfer Radical Polymerization (ATRP) is a newly developed method to obtain controlled molecular structure, molecular weight, low dispersity and functionalized polymers. Zwitterion is a kind of compound simultaneously containing negative and positive groups in its molecular chains, its excellent abilities to resist non-specific protein adsorption, platelet adhesion and cell adhesion makes it a potential bio-interface material for medical applications.In this study, ATRP has been introduced to surface modification with diblock copolymers via "grafting to" method. Diblock copolymer coatings were first prepared and then reacted with cellulose and medical alloy316L to improve the surface biocompatibility with convenience "one-step" method. The anti-fouling properties containing protein adsorption, platelet adhesion and cell adhesion were improved significantly.(1) A commercial silicane coupling reagent monomer was used to synthesize a novel functional macromolecular initiator via ATRP, with DPI=1.35and number average molecular weight3500. The biofunctional monomer MPC was then added onto the macromolecular to prepare a series of biocompatible copolymer coatings. Monomer molar ratio with2-methacryloyloxyethyl phosphorylcholine (MPC) differs as14:15,14:30,14:50,14:70and14:200. Distinguished copolymer solutions were premaded. Micelles with series sizes and distinguished coating behaviors were observed when the two monomers ratio differed. Copolymer with a quite long MPC block formed a small micelle.(2) After a convenient "one-step" reaction under mild condition and TEA catalyst, CMs were modified by these copolymer solutions. The functional silicane groups reacted with the surface hydroxyl groups and interconnected with each other while the PC groups exposed to air and presented high hydrophilic properties, which was proved by SCA. Surface morphology changes were also monitored by AFM. The surface biocompatibility was then tested by protein adsorption using BSA, fibrinogen and plasma as resources. Platelet adhesion and293T cell adhesion also reduced by the copolymers coating surface. Compared with the protein adsorption amount in different series, P(14:70) presented the best effect of all the candidates. Based on the experiments and date above, this novel diblock copolymer promises to be useful in biomedical application.(3) Under a mild condition, the copolymer has high activity with the316L surface dangling bonds when the triethylamine (TEA) catalyst presents. AFM and static contact angle measurements demonstrated obvious surface topology changes and high hydrophilic properties. The adsorption of bovine serum albumin (BSA) and fibrinogen on the PMPC surface was monitored by the BCA method and the results showed the coating film had excellent protein resistance even with the background absorbance by metal ions released from the substrates. Platelet adhesion and cell adhesion were also reduced considerably. HEK293cell adhesion was reduced by about50%and fibroblast (L929) was reduced by more than75%%even under3-days-adhesion experiment. The phenomena proved the316L stainless steel surface coating effective biocompatibility by the copolymer modification.