Study of immobilized heparin in varied pH values onto porous n on-woven fabric surface

This study utilized antenna-coupling O₂ microwave plasma to activate non-woven polypropylene (PP) fabric surface and graft with acrylic acid (AAc). Heparin was then immobilized using a carbodiimide as coupling agent. Surface analyses by ATR-FTIR and ESCA traced the presence of the functional groups. To quantify the immobilized heparin, Toluidine Blue method was used. The blood clotting effect of heparin-bonded surfaces was evaluated by activated partial thrombin time (aPTT), thrombin time (TT), fibrinogen concentration and platelet adhesion on the porous surfaces. Current result demonstrated that PP surface with AAc-grafted amount of ca. 236 μg.cm^-2; the immobilized heparin was gained ca. 9-13 μg.cm^-2, varied with pH values during preparation. After human plasma incubated with heparinized surfaces, the concentration of fibrinogen and the ratio of platelets adhesion were decreased in human plasma; however, the required time for thrombination (by aPTT and TT tests) was significantly increased. Consequently, the bioactivity on the heparinized surfaces was validated; and this was influenced by the variation of pH values in sample preparation or thus ionic strength formed at the modified surfaces. The immobilized amount was simultaneously correlated with the degree of bioactivity.