A NOVEL APPROACH TO NONTHROMBOGENIC POLYMER SURFACES

肝素释放和固定化聚合物已经证明 显著减少血栓形成， 血液/聚合物界面。 体外研究显示， 使用所设计的系统预防纤维蛋白形成， 主要是由于肝素活性，在APTT、TT和抗- 因子Xa测试。 肝素固定表面的体内研究 显示最小的纤维蛋白形成，尽管血小板粘附 并没有明显减少。 在该应用中，商业肝素和分级肝素两者都可以用于制备肝素。 将被固定在模型表面（Sepharose 6 B）上， 既使用亲水性又使用极性的实用表面（聚氨酯） 间隔臂基团。 根据我们之前的研究， 嵌段间隔物界面的亲水环境 将减少蛋白质吸附和随后的血小板粘附。 肝素-PGE 1缀合物也将固定在表面上 通过相似的化学作用实现双重药理作用 减少纤维蛋白形成和抑制血小板粘附。 实验参数，亲水环境，通过 亲水性间隔基团、肝素活性和肝素-PGE 1 共轭，将通过使用设计变量进行研究 表面之间的间隔基团长度不同， 固定化肝素或肝素-PGE 1缀合物。 动物 实验包括兔离体分流（短期）导管 植入物（短期）和狗血管植入物（长期）。 实验数据的结果将验证可能 血栓形成机制（吸附的 蛋白质、凝血因子和血小板相互作用），并提供 更有效的血液相容性设计模型 聚合物表面 这将消除系统性或 在使用血液的患者中施用抗凝剂 接触医疗器械。

Heparin releasing and immobilized polymers have demonstrated a significant reduction in thrombus formation on the blood/polymer interface. In vitro studies revealed that prevention of fibrin formation using the designed systems were mainly due to heparin activity, in terms of APTT, TT, and anti- Factor Xa tests. In vivo studies of heparin immobilized surfaces displayed minimum fibrin formation, although platelet adhesion was not significantly reduced. In this application, both commercial and fractionated heparin will be immobilized onto a model surface (Sepharose 6B) and a practical surface (polyurethane) using both hydrophilic and polar spacer arm groups. Based on our previous studies it is expected that the hydrophilic environment of the block spacer interface will reduce protein adsorption and subsequent platelet adhesion. Heparin-PGE1 conjugate will also be immobilized on the surface by similar chemistry to achieve the dual pharmacological actions of reducing fibrin formation and inhibiting platelet adhesion. The experimental parameters, hydrophilic environment via hydrophilic spacer groups, heparin activity, and a heparin-PGE1 conjugate, will be investigated by utilizing a design variable of differing spacer group lengths between the surface and immobilized heparin or heparin-PGE1 conjugate. The animal experiments include rabbit ex vivo shunt (short term) catheter implant (short term) and vascular implant in dogs (long term). The results of the experimental data will verify possible mechanisms involved in thrombus formation (role of adsorbed protein, clotting factors, and platelet interaction) and provide a more effective model for the design of a blood compatible polymer surface. This will eliminate the need or systemic administration of anticoagulants in patients using blood contacting medical devices.