Surface Analysis of Poly(ether urethane) Blending Stearyl Poly(ethylene oxide) Coupling Polymer

The influence of fluorocarbon chain and phosphorylcholine on the improvement of hemocompatibility: a comparative study in polyurethanes

The synergistic effect of a fluorocarbon chain and phosphorylcholine groups on the improvement of hemocompatibility in polyurethanes was investigated.

Lipid-like Diblock Copolymer as an Additive for Improving the Blood Compatibility of Poly(lactide-co-glycolide)

To optimize the blood biocompatibility of poly(lactide-coglycolide) (PLGA), lipid-like diblock copolymer poly(DL-lactide)-block-poly(2-methacryloyloxyethyl phosphorylcholine) (PLA-b-PMPC) was employed as a surface-modifying additive. The blends of PLGA and PLA-b-PMPC coated poly(ethylene terephthalate) membranes were prepared by dip-coating. ATR-FTIR spectroscopy showed the incorporation of phosphorylcoline groups in the blends and contact angle results indicated that the hydrophilicity of the blends improved with increasing PLA-b-PMPC content. The plasma recalcification time of polymer coating was prolonged and the amount of adherent platelets on coating surface was decreased by introducing PLA-b-PMPC. The adhesion of polymer coating on the gold electrode of quartz crystal microbalance was monitored and PLGA containing PLA-b-PMPC additives showed excellent polymer—metal adhesion. These results show that the blends of PLGA and lipid-like PLA-b-PMPC could be used as high performance biodegradable polymer coatings for blood contact medical devices.

Poly(lactide-co-glycolide)/titania composite microsphere-sintered scaffolds for bone tissue engineering applications

The objective of this study was to synthesize and characterize novel three-dimensional porous scaffolds made of poly(lactic-co-glycolic acid) (PLGA)/nano-TiO(2)-particle composite microspheres for potential bone repair applications. The introduction of TiO(2) component has been proven capable of largely enhancing mechanical properties of PLGA/TiO(2) microsphere-sintered scaffold ("PLGA/TiO(2)-SMS"). In addition, composite nano-TiO(2) additives are capable of inducing an increased arrest of adhesive proteins from the environment, which benefits cell attachment onto the scaffolds. Osteoblast proliferation and maturation were evaluated by MTT assay, alkaline phosphatase (ALP) activity, and bony calcification assay. The results indicate that osteoblasts cultured on the composite scaffolds with different TiO(2) content (0, 0.1, and 0.3 g/1 g PLGA) display increased cell proliferation compared with pure PLGA scaffold. When cultured on composite scaffolds, osteoblasts also exhibit significantly enhanced ALP activity and higher calcium secretion, with respect to those on the pure PLGA scaffolds. Taken together, PLGA/TiO(2)-SMSs deserve attention utilizing for potential bone-repairing therapeutics.

Synthesis and characterization of cholesterol-poly(ethylene glycol)-poly(D,L-lactic acid) copolymers for promoting osteoblast attachment and proliferation

A novel cholesterol-poly(ethylene glycol)-poly(D,L-lactic acid) copolymer (CPEG-PLA) has been synthesized as a potential surface additive for promoting osteoblast attachment and proliferation. The gel permeation chromatography (GPC) and nuclear magnetic resonance spectroscopy (NMR) results indicated the product had expected structure with low polydispersities in the range of 1.1-1.5. By blending the poly(D,L-lactic acid) (PLA) with CPEG-PLA, the surface of modified PLA membrane was investigated by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle. The results revealed the enrichment of PEG chain on the surface. Osteoblast cell line (MC3T3) was chosen to test the cell behavior on modified PLA membranes. The osteoblast test about cell attachment, proliferation, cell viability and cell morphology investigation on CPEG-PLA modified PLA substrates showed the CPEG-PLA with 15 and 5 ethylene glycol units promoted osteoblast attachment and growth, while the CPEG-PLA with 30 ethylene glycol units prevent osteoblast adhesion and proliferation. This simple surface treatment method may have potentials for tissue engineering and other biomedical applications.

Poly(D,L-lactic acid)-block-(ligand-tethered poly(ethylene glycol)) copolymers as surface additives for promoting chondrocyte attachment and growth

The poly(D,L-lactic acid)-block-(ligand-tethered poly(ethylene glycol)) copolymer was explored to engineer poly(D,L-lactic acid) (PLA) material to promote chondrocyte attachment and growth. The poly(D,L-lactic acid)-block-poly(ethylene glycol) copolymer (PLE) was synthesized by a coupling reaction between PLA and poly(ethylene glycol) (PEG) (M(n) 1000, 2000, and 4000 respectively), with the use of 4,4'-methylenediphenyl diisocyanate (MDI). Then the PLE was activated by methyl sulfonyl chloride and the amino acids or arginine-glycine-aspartic acid tripeptide (RGD) was attached, which was verified by the ninhydrin-UV method. The modified PLA films were simply prepared by blending PLA with PLE derivatives. ATR-FTIR, XPS, contact angle, and AFM results clearly showed that the PEG chain stably enriched on the surface of PLE-modified PLA films. The chondrocyte cytocompatibility test showed the modified PLA films could significantly improve chondrocyte attachment and proliferation.

Novel human endothelial cell-engineered polyurethane biomaterials for cardiovascular biomedical applications

A tri-block coupling-polymer composed of 4,4'-methylenediphenyl diisocyanate and poly (ethylene oxide) (PEO), abbreviated MPEO, was used as the template surface-modifying additive (SMA), based on which selected amino acids (lysine, arginine, glycin, and aspartic acid) and RGD peptide were respectively conjugated as functional endgroups of the PEO spacer-arms through sulfonyl chloride-activation routes. After the immobilization of biofunctional factors, the SMA-MPEO derivatives were noncovalently introduced onto the biomedical poly(ether urethane) (PEU) surfaces by physical blending methods. The SMA synthesis and PEU surface modification were monitored and analyzed by nuclear magnetic resonance spectroscopy, attenuated total reflection-infrared spectroscopy, and X-ray photoelectron spectroscopy. The human umbilical vein endothelial cells (HUVECs) were collected and harvested manually by collagenase digestion. The cell culture was performed respectively on the MPEO derivative-modified PEU surfaces and also on the surfaces of the commercially available polystyrene cell-culture plates (TCPS) for control. The cell adhesion rates and cell proliferation rates of the in vitro cultivated HUVEC were measured using flow cytometry. The individual cell viability rates were determined with MTT assay. The cell morphologies of the living HUVECs were investigated by optical inverted microscopy, and more detailed information was acquired from scanning electrical microscopy. The results indicated that the efficacy of SMA functional endgroups was the dominant factor for HUVEC compatibility; the proper-sized PEO spacers (M(w) 2 k) could support and mobilize the functional endgroups, optimizing the surface (interface) environment for the cell growth. As the endgroups of the SMA-MPEO derivatives and the bio-functional factors, the basic amino acids (lysine and arginine) demonstrated similar performances to that of the widely acknowledged cell growth-promoter, RGD peptide, which were superior to TCPS. Therefore, these MPEO derivative-modified PEU materials are promising to serve as novel polymeric permanent implants or interventional devices for cardiovascular biomedical applications.

Selective binding of albumin on stearyl poly(ethylene oxide) coupling polymer-modified poly(ether urethane) surfaces

A tri-block-coupling polymer of stearyl poly(ethylene oxide)-4,4'-methylene diphenyl diisocyanate-stearyl poly(ethylene oxide) (MSPEO), was used as a surface modifying additive (SMA) and the MSPEO-modified poly(ether urethane) (PEU) surfaces were prepared by the process of dip-coating. The surface analysis by XPS revealed the surface enrichment of poly(ethylene oxide) (PEO). On the coating-modified surfaces, the bovine serum albumin (BSA) adsorption, respectively, from the low and high BSA bulk concentration solutions was correspondingly characterized by the methods of radioactive 125I-probe and ATR-FTIR. The bovine serum fibrinogen (Fg)-adsorption from the Fg bulk solution and the BSA-Fg competing adsorption from the BSA-Fg binary solutions were also characterized by radioactive 125I-probe. The reversible BSA-selective in situ adsorption on MSPEO-modified PEU surfaces were achieved, and the performance of blood compatibility on the coating-modified surfaces was also confirmed, respectively, by plasma recalcification time (PRT) and prothrombin time (PT) tests.

Blends of stearyl poly(ethylene oxide) coupling-polymer in chitosan as coating materials for polyurethane intravascular catheters

To optimize the surface biocompatibility of the intravascular catheter, an amphiphilic coupling-polymer of stearyl poly (ethylene oxide) -co- 4,4'-methylene diphenyl diisocyanate-co- stearyl poly (ethylene oxide), for short MSPEO, was specially designed as the surface modifying additive (SMA). The blend of MSPEO in chitosan was coated on the outer wall of the catheters by the dip-coating method. The surface analysis was carried out by ATR-FTIR and contact angle measurements. The surface enrichment of MSPEO was confirmed. On the water interface, the larger the molecular weight of PEO was, the higher the surface enrichment. While on air interface, the case was the contrary. Three kinds of static test of clotting time, plasma recalcification time (PRT), prothrombin time (PT), and thrombin time (TT), as well as the static platelet adhesion experiment were carried out. The results indicated that the coated surface could resist the clotting effectively. In order to test the blood-compatibility of the coated catheters under a shear of blood flow, the dynamic experiment was performed through a closed-loop tubular system with the shear rate of 1500 s(-1). The results of blood regular testing at six different times (0, 5,10, 20, 30, and 60 min) indicated that the biocompatibility of the coating was nearly ideal. Finally, the SMA-MSPEO was proved to be non-chronic-toxic by animal experiments with rats and suitable as a coating material for clinical use.

Surface coating of stearyl poly(ethylene oxide) coupling-polymer on polyurethane guiding catheters with poly(ether urethane) film-building additive for biomedical applications

Three types of stearyl poly(ethylene oxide) (SPEO) with Mn of 2,300, 6,000 and 12,000 were synthesized; accordingly, three types of amphiphilic coupling-polymer SPEO-MDI-SPEO (MSPEO) were prepared by the reactions with 4,4'-methylene diphenyl diisocyanate (MDI). As the surface-modifying additives (SMA), MSPEOs were coated onto the outer wall of the medical guiding catheters. Due to the lack of stability, when coated, MSPEO blended with the film building agent (FBA), poly(ether urethane) (PEL). The process of coating was performed with a lifter. With invariable speed, the PU guiding catheter was vertically dipped into the coating mixture of SMA-MSPEO and FBA-PEL. The surface analysis was carried out by ATR-FTIR and contact angle measurements. It was proved that the surface enrichment of PEO on water interface was much higher than that on air interface. Three kinds of static clotting time tests, PRT, PT and TT, as well as the static platelet adhesion experiment were performed. The results indicated that the coated surface could resist the blood coagulation effectively. In order to test the blood compatibility of the coated catheters under a shear of blood flow, the dynamic experiment was performed with a closed-loop tubular system under a shear rate of 1,500 s(-1). The blood regular testing was carried out on the samples taken out at six different times (0, 5,10, 20, 30 and 60 min). The results were ideal. Finally, the SMA-MSPEO was proved to be non-acute-toxic by LD50 test.