Effect of microstructure of poly(propylene‐oxide)‐segmented polyamides on platelet adhesion

Abstract

The relationship between microstructure and platelet adhesivity of six types of poly(propylene oxide) (PPO)-segmented polyamides based on the polyamide segments nylon 210, 310, 410, 510, 610, and 710 were investigated. These multiblock PPO-segmented copolymers were prepared by interfacial polycondensation. Physical characterization of these copolymers was by means of thermal analysis, transmission electron microscope, wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS). The WAXD and SAXS measurements showed that the copolymers had microstructures containing crystalline and amorphous phases and that these microstructures, represented by means of crystallite thickness and long period, varied with incorporation of PPO segments. Blood compatibility of these copolymers was evaluated by estimating the amount of adhering platelets on the copolymer surfaces. The amount of adhering platelets was minimum for the surfaces of the copolymers having a crystallite thickness of 6.0-6.5 nm and a long period of 12-13 nm. This result suggests that the particular size and distribution of the crystalline and amorphous phases in the copolymer could be determining factors for suppressing platelet adhesion on the copolymer surface, and that the control of these factors could lead to ideal antithrombogenic polymers.

An Overview of the Biocompatibility of Polymeric Surfaces

“…Similar antithrombogenic behavior was found by the same group in cases of diblock copolymers of poly(HEMA) and either styrene or PDMS; these block copolymers also exhibited a hydrophilic-hydrophobic microphase separated structure (64). Examples of other hydrophobic-hydrophilic block copolymers include polydimethylsiloxane-poly(y-benzyl L-glutamate) block copolymers (65), and poly(propylene oxide)-polyamide copolymers (66). Although the mechanism of action by which SMAs and microphase-separated structures decreases blood protein and cellular activation is not precisely known, the mosaic structure of microdomains with different polarity may lead to more uniform fibrinogen adhesion such that platelet receptor sites are unexposed or unavailable for interaction (62,63).…”

Polymorphism in porous poly(vinylidene fluoride) membranes formed via immersion precipitation process

“…To improve the surface hydrophilicity and anti-fouling ability of PVDF membrane, considerable efforts have been made to alter the surface chemical composition by surface coating [22,23], surface grafting [24,25], and physical blending [26][27][28] semi-crystalline polymeric systems [29][30][31] have demonstrated that the surface properties vary with the crystalline-amorphous microstructure in the surface layer in terms of adhesiveness, protein adsorption, and blood compatibility. Thus, a question should be addressed whether the crystalline structure has any effect on the properties of PVDF membrane.…”

The role of polymer surface degradation and barium sulphate release in the pathogenesis of catheter-related infection

“…These block copolymers, also called SMAs, are blended in a reactive mixture with polyurethane polymer resins and coated on device surfaces, as was the case for the SMA dialysis catheter (MC) we used (US patent 6841255). SMAs improve biocompatibility by delaying contact activation and reducing thrombin-antithrombin complex generation [12], and diminish the thrombogenicity by hampering adhesion of platelets [22,23]. The SMA-coated catheters we used had a very smooth surface compared to the conventional catheters, and more importantly, this coating prevented the release of BaSO 4 by sealing the surface with a continuous and closed polymer film.…”