Blood Compatibility Of Polyurethanes Research Articles

Biomimetic surface modification of polyurethane with phospholipids grafted carbon nanotubes.

To improve blood compatibility of polyurethane (PU), phospholipids grafted carbon nanotubes (CNTs) were prepared through zwitterion-mediated cycloaddition reaction and amide condensation, and then were added to the PU as fillers via solution mixing to form biomimetic surface. The properties of phospholipids grafted CNTs (CNT-PC) were investigated by thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance ((1) H NMR). The results indicated that the phospholipids were grafted onto CNTs in high efficiency, and the hydrophilicity and dispersibility of the modified CNTs were improved effectively. The structures and properties of composites containing CNT-PC were investigated by optical microscope, XPS, and water contact angles. The results indicated that phospholipids were enriched on the surface with addition of 0.1 wt % of CNT-PC, which significantly reduced protein adsorption and platelet adhesion. The method of carrying phospholipids on the nanofiller to modify polymers has provided a promising way of constructing biomimetic phospholipid membrane on the surface to improve blood compatibility.

Effects of types and length of soft-segments on the physical properties and blood compatibility of polyurethanes

Segmented polyurethane (SPU) materials based on different soft-segment component (PPG, PTMO and PBA) and various length of soft-segment (molecular weight of PBA: 500, 700 and 1000) were synthesized in this research. The soft-segment components were synthesized from polyether-polyols (PPG and PTMO) or from polyester-polyol (PBA). The physical properties and structure characterization of the synthesized SPUs were fully investigated using differential scanning calorimetry (DSC) analysis, and stress-strain measurements. Blood compatibility was evaluated with the platelet adhesion ratio (PAR) and the morphological observation for adhering platelets. Our results showed that the physical properties and blood compatibility of SPUs were closely related to its composition, which was controlled by (1) the types of the soft-segment component employed and (2) the length of soft segments. Polyether-polyol-based SPUs exhibited greater phase separations, poorer tensile strengths, and better blood compatibility, compared with polyester-polyol-based SPUs. SPUs with shorter soft-segment component exhibited greater phase mixing, higher tensile strength, but lower blood compatibility of SPUs, as compared with its counterparts with longer soft-segment component.

Studies on in vitro biostability and blood compatibility of polyurethane potting compound based on aromatic polymeric MDI for extracorporeal devices

Polyurethane potting compound based on aromatic isocyanurate of polymeric MDI, poly propylene glycol (PPG400) and trimethylol propane (TMP) has significant favourable properties, good pot life and setting characteristics. The cured potting compound of this formulation has appreciable thermal stability and mechanical properties. In vitro biostability of cured potting compound has been found to be excellent without any significant degradation in simulated physiological media and chemical environment. Studies on blood-material interaction and cytotoxicity reveal in vitro blood compatibility and compatibility with cells of this potting compound.

LARGELY IMPROVED BLOOD COMPATIBILITY OF POLYURETHANE BY BLENDING WITH FLUORINATED PHOSPHATIDYLCHOLINE POLYURETHANE

The improvement of biocompatibility of polyurethanes was investigated. The results demonstrate that the blood compatibility of polyurethanes can be further improved by just simply mixing with the fluorinated phosphatidylcholine poly(carbonate urethane)s (FPCPCUs). The solution blending was done by mixing poly(ether urethane) (PEU) with FPCPCU in different compositions. An increased blood compatibility of the blend films was observed with the increase of FPCPCU content, and when FPCPCU content reached to 40 wt% (40FPCPCU film), 6 times and 23 times decrease of platelet adhesion number have been achieved, compared with that of FPCPCU and PEU, respectively. More interestingly, the blend films showed even better blood compatibility than that of FPCPCU. DSC, AFM and XPS were used to characterize the miscibility and surface structure of the blends film. The largely improved blood compatibility was rationalized based on the combined effect of phase separation between PEU and FPCPCU and the formation of surface nanostructures induced by segregation of FPCPCU at the surface.

Atomic force microscopy visualization of poly(urethane urea) microphase rearrangements under aqueous environment

Polyurethane biomaterials are a critically important class of polymers used in a variety of medical devices. It has been suggested that the good blood compatibility of polyurethanes arises from nanoscale chemical heterogeneities at the surface as a consequence of the microphase separated morphology. In this study, we used tapping mode atomic force microscopy with phase imaging under aqueous conditions to visualize the distribution of the surface microphases for a series of poly(urethane urea) block co-polymers with varying hard segment content. The surfaces were prehydrated for 24 h under a flow of 1 mM phosphate buffer. Topographic images showed the formation of nanometer-sized raised features on the surface, having lateral dimensions of 50–70 nm and heights of 10–15 nm. Phase images, reflecting the local distribution of the mechanical properties under aqueous conditions, were quite different from those obtained in ambient conditions, consistent with water-induced structural reorientation. Images suggest that there is little soft phase material at the polymer surface in the presence of water, while images acquired after dehydration of the samples show that the surface layer remains rich in hard domains, indicating that the films do not return to their original states over the time period studied.

Effects of polydimethylsiloxane grafting on the calcification, physical properties, and biocompatibility of polyurethane in a heart valve

AbstractSegmented polyurethane (PU) has proven to be the best biomaterial for artificial heart valves, but the calcification of polyurethane surfaces causes serious problems in long‐term implants. This work was undertaken to evaluate the effects of polydimethylsiloxane (PDMS) grafting on the calcification, biocompatibility, and blood compatibility of polyurethane. A grafted polyurethane film was compared with virgin polyurethane surfaces. Physical properties of the samples were examined using different techniques. The hydrophobicity of the polyurethane films increased as a result of silicone modification. The effects of surface modification of polyurethane films on their calcification and fibroblast cell (L 929) and platelet behavior were evaluated in vitro. Fourier transform infrared spectroscopy indicated the direct involvement of the polyether soft segments of the polymer in the calcification process. Scanning electron microscopy of films indicated that grafting of silicone rubber to the surface of polyurethane successfully prevented the calcification process. The morphology of fibroblast cells that adhered to the PU films and modified films was similar to that of controls and showed the same proliferation. On the other hand, grafting PDMS onto PU did not affect the amount of platelets that adhered to the polyurethane surfaces. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 758–766, 2005

Effect of Fabrication, Sterilization and Mediators - Blood Compatibility of Polyurethanes

The possible changes in the surface and physical properties of polyether urethane urea (PEUU) implants, including their interaction with blood, due to the different preparation methods, sterilization techniques and long term storage in different environmental conditions have been investigated by conducting the studies of mechanical properties, contact angle, platelet adhesion and protein adsorption. Considerable variations in the mechanical properties have been observed for the PEUU grafts stored in different conditions. Changes in platelet adhesion and albumin adsorption have also been observed in the case of samples that underwent different sterilization methods. The effect of mediators like bromelain, an enzyme present in pineapple juice, on albumin adsorption and platelet adhesion on PEUU surfaces have been investigated. It seems the presence of pineapple juice increases the adsorption of albumin and reduces the adhesion of platelets on PEUU surfaces.