Surface modification of polyurethane for enhanced blood compatibility

Synthesis and evaluation of a small library of graftable thrombin inhibitors derived from (l)-arginine

Novel piperazinyl-amide derivatives of N-alpha-(aryl-sulfonyl)-L-arginine were synthesized as graftable thrombin inhibitors, in the context of biomaterials' design. The possible disturbance of biological activity due to a variable spacer-arm fixed on the N-4 piperazinyl position and the introduction of a trifluoromethyl group as XPS (X-ray Photoelectron Spectroscopy) tag on the sulfonamide moiety were evaluated in vitro against human alpha-thrombin. All the compounds of the library were found to be active at the micromolar level, as the reference TAME (N-tosyl-L-arginine methyl ester). The blood compatibilization improvement of poly(ethylene terephthalate) (PET) membrane, coated or grafted by wet chemistry treatment with one representative inhibitor of the library, was also evaluated, showing interesting decrease in blood clot formation.

Preparation and surface properties of PEO-sulfonate grafted polyurethanes for enhanced blood compatibility

In order to improve the thromboresistance of the commercial polyurethane(PU), its surface modification was accomplished by three new different methods and their surface characteristics were investigated using ATR-FTIR, ESCA, SEM, and dynamic contact angle measurements. Sulfonations using propane sultone were performed directly onto PU or onto hydrophobic dodecanediol (DDO) grafted PU or onto hydrophilic poly(ethyleneoxide) (PEO) grafted PU. ESCA data coincided well with ATR-IR results, as more 0 at. % for PEO grafted PUs and the presence of S for the sulfonated PUs were revealed. At SEM observation the surfaces of PU-DDO and PU-PEO were relatively smooth, whereas all the sulfonated PU surfaces showed excellent smoothness and homogeneity. The hydrophilicity of the surfaces was considerably increased after PEO grafting or sulfonation. In addition, all the sulfonated PU surfaces, particularly PU-PEO-SO3, which has further hydrophilicity, exhibited complete wetting behavior due to the negatively charged SO3 groups.

Negative cilia concept for thromboresistance: synergistic effect of PEO and sulfonate groups grafted onto polyurethanes

In order to investigate the interaction between various sulfonated polyurethanes (PUs) and blood, a commercial PU surface was chemically modified by poly(ethylene oxide) (PEO), dodecanediol(DDO), and propane sultone to give hydrophilic, hydrophobic, and negative sulfonated surfaces, respectively. The blood compatibility of modified PUs was evaluated by an in vitro platelet adhesion test, activated partial thromboplastin time (APTT), and prothrombin time (PT) measurements as well as an ex vivo rabbit A-A shunt method. In the platelet adhesion test, the hydrophilic PEO grafted PUs showed less platelet adhesion than untreated PU and hydrophobic DDO grafted PU. Sulfonated PU-PEO exhibited a lower degree of adhesion and shape change of platelet. The APTT and PT, especially APTT, of the sulfonated PUs were extended, whereas those of PU-PEO and PU-DDO did not show any significant change compared with untreated PU. Meanwhile, in the ex vivo experiment, hydrophilic PEO grafted PUs showed longer occlusion times than untreated PU or hydrophobic DDO grafted PU. In addition, the incorporation of SO3 groups at the end of PU-DDO and PU-PEO, particularly PU-PEO-SO3, exhibited an enormous prolongation in occlusion time, indicating a synergistic effect of the hydrophilic PEO and the negative SO3 groups on thromboresistance. These occlusion times corresponded well to in vitro evaluation results: the less adhesion and shape change of platelet and the longer APTT and PT, the more extended the ex vivo occlusion time.