Preparation Of Polymer Brushes And Research On Their Protein Adsorption Behavior

The property of the biomedical materials interfaces, especially its interaction with biomacromolecules (such as protein), is the key problem to research these materilas. Two methods, such as "grafting to" and "grafting from" methods, were employed to obtain polymer brushes. Proteins adsorption behavior on these modified interfaces were researched.Thiol-terminated polymers poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC-SH), poly(N,N-isopropylacrylamide) (PNIPAM-SH) and poly(tert-Butyl acrylate) (PtBA-SH) were synthesized and the polymers were grafted on the gold surfaces of quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR) sensor chips to form brushes. The grafting process of the polymer brushes as well as protein adsorption onto the brush layers was monitored by in-situ QCM-D and SPR techniques. By examining the changes in frequency and dissipation factor as well as the value of ((?)D/(?)f) from QCM-D measurements, different stages of the polymer grafting and protein adsorption are distinguished. The most interesting discovery is the conformation change of BSA protein adsorption from a weakly adsorbed native state to a strongly immobilized denatured state on the polymer brushes. The corresponding change in BSA adsorption from a reversible state to an irreversible state was confirmed by SPR measurements. For gold surface, conformation change occurs immediately after the protein adsorbed on the surface. After modification with PNIPAM and PtBA, about 52% BSA adsorption amount was reduced. About 97% BSA adsorption amount was reduced after modification with PMPC.Cell outer membrance mimetic and other polymer brush were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). Water contact angle, X-ray photoelectron spectroscopy, and atomic force microscopy were used to determine the chemical composition, morphology, thickness and other properties of the modified surfaces. It is proved that four monomers were successfully grafted to the surface. The modified surfaces are smooth and the grafting density larger than 0.35 chains·nm-2. It is interesting to observe that protein adsorption on behavior were studied on these four modified surfaces.