An ideal surface for many biomedical applications would resist non-specific protein adsorption while at the same time triggering a specific biological pathway. Based on the approach of selectively binding albumin to free fatty acids, stearyl groups were immobilized onto poly (styrene) backbone via poly (ethylene oxide) side chains. X-ray photoelectron spectroscopy (XPS) analysis indicates substantial surface enrichment of the stearyl poly(ethylene oxide) (SPEO). In an aqueous environment, the surface rearrangement is limited, as proved by dynamic contact angle tests. The comb-like copolymer presents a special hydrophobic surface with high SPEO surface density, which may be due to the & tail like' SPEO architecture at the copolymer/water interface. Protein adsorption tests confirm that the comb-like surfaces adsorb high levels of albumin and resist fibrinogen adsorption very signifi cantly. The surfaces prepared in this research attract and reversibly bind albumin due to the synergistic action of the PEO chains and the stearyl end groups.

A tri-block-coupling polymer, "PEO-MDI-PEO" ["poly (ethylene oxide)-4,4'-methylene diphenyl diisocyanate-poly (ethylene oxide)", abbreviated "MPEO"], was used to react with a triazine dye, Cibacron Blue F3G-A (ciba), in an alkaline environment. The product of this nucleophilic reaction was a penta-block-coupling polymer, "ciba-PEO-MDI-PEO-ciba" (abbreviated "cibaMPEO"). The cibaMPEO-modified poly (ether urethane) (PEU) surfaces were prepared by dip-coating and detected by XPS. The surface enrichment of both ciba endgroups and poly (ethylene oxide) spacer-arms was revealed. On the modified surfaces, bovine serum albumin (BSA)-adsorbing experiments were carried out, respectively, in the low and high BSA bulk-concentration solutions, and accordingly, the methods of radioactive 1251-probe and ATR-FTIR were, respectively, employed for the characterization. The competitive dsorption of BSA and bovine serum fibrinogen (Fg) in the BSA-Fg binary solutions was also studied using a 125I-probe, and through which the reversibly BSA-selective adsorption on cibaMPEO-modified PEU surfaces was confirmed. Finally, the improvement of blood-compatibility on the modified surfaces was verified by the plasma recalcification time (PRT) test.

Poly (vinyl chlorides)-graft-[v-stearylpoly (ethylene oxide)] (PVC-g-SPEO), which has a poly (vinyl chloride) (PVC) backbone, poly (ethylene oxide) (PEO) side chain, and stearyl end groups, has been synthesized. Selforganizing blends of the amphiphilic comb polymer in poly-(vinyl chlorides) have been examined as a means to create albumin preferential surfaces on polymer films. X-ray hotoelectron spectroscopy (XPS) analysis indicates substantial surface segregation of the PVC-g-SPEO. A surface concentration of 59.9 EO wt % is achieved by the solution casting and heat treatment of a film with a bulk concentration of only 3.78 EO wt %. In the aqueous environment, the surface rearrangement of PVC-g-SPEO/PVC blend film is limited (to J.J.) and presents a high interfacial energy and high epolar component of interfacial energy due to the "tail-like" SPEO side chain. Protein adsorption tests confirm that PVC-g-SPEO/PVC blend films absorb high levels of albumin and dramatically resist fibrinogen adsorption. Surfaces to attract and reversibly bind albumin, which might diminish the occurrence of thrombosis, inflammation, and infection, are developed by self-organizing blends of the amphiphilic comb polymer in poly (vinyl chlorides).

Summary: Novel biomimetic surfactants based on cholesterol as the hydrophobic segment and poly[2-(methacryloyloxy) ethyl phosphorylcholine] (pMPC) as the hydrophilic segment were synthesized in the present study by atom transfer radical polymerization (ATRP) of 2-(methacryloyloxy)-ethyl phosphorylcholine (MPC) using a cholesterol-based macroinitiator. The association behavior of cholesterolblock-poly[2-(methacryloyloxy)ethyl phosphorylcholine] (Chol-pMPCs) in aqueous solution was studied by 1H NMR spectroscopy, fluorescence probe technique, and atomic force microscopy (AFM). The 1HNMRspectrum of the polymer in CD3OD showed both the cholesterol group and the phosphorylcholine group while the cholesterol group did not appeared in the 1H NMR spectrum of the polymer in D2O, which implied the formation of a micelle structure. Fluorescence excitation spectra of a pyrene probe solubilized in the aggregates of Chol-pMPCs suggested the presence of a critical micelle concentration (cmc) in water. The critical micelle concentrations of the polymers CMPC10, CMPC20 and CMPC40 were determined to be 7.27×10-3, 13.47×10-3, and 20.77×10-3mg•mL-1, respectively. AFM images of the aggregates on mica suggested that the pMPC block formed the biocompatible micelle coronas and the cholesterol block formed the hydrophobic micelle cores. These newbiomimetic diblock copolymers were evaluated as "stealthy" nanocapsules for the delivery of hydrophobic drugs. The anti-cancer drug adriamycin (ADR) was chosen as a hydrophobic drug to be incorporated into the inner core of the micelles and the morphology of the drug-loaded micelles were observed by AFM. Schematic of the biomimetic block copolymers and their micellization, and an AFM image of the micelles deposited on mica.

A "CBABC"-type pentablock coupling polymer, mesylMPEO, was designed and synthesized to promote human endothelial cell growth on the surfaces of polyurethane biomaterials. The polymer was composed of a central 4,4'-methylenediphenyl diisocyanate (MDI) coupling unit and poly(ethylene oxide) (PEO) spacer arms with methanesulfonyl (mesyl) end groups pendent on both ends. As the presurface modifying additive (pre-SMA), the mesylMPEO was noncovalently introduced onto the poly(ether urethane) (PEU) surfaces by dip coating, upon which the protein/peptide factors (gelatin, albumin, and arginine-glycine-aspartic acid tripeptide [RGD]) were covalently immobilized in situ by cleavage of the original mesyl end groups. The pre-SMA synthesis and PEU surface modification were characterized using nuclear magnetic resonance spectroscopy (1H NMR), attenuated total reflection infrared pectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). Human umbilical vein endothelial cells (HUVEC) were harvested manually by collagenase digestion and seeded on the modified PEU surfaces. Cell adhesion ratios (CAR) and cell proliferation ratios (CPR) were measured using flow cytometry, and the individual cell viability (ICV) was determined by MTT assay. The cell morphologies were investigated by optical inverted microscopy (OIM) and scanning electrical microscopy (SEM). The gelatin- and RGD-modified surfaces were HUVEC-compatible and promoted HUVEC growth. The albumin-modified surfaces were compatible but inhibited cell adhesion. The results also indicated that, for HUVEC in vitro cultivation, the cell adhesion stage was of particular importance and had a ignificant impact on the cell responses to the modified surfaces.