Byun Y, Jacobs H A, Kim S W
Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City 84108.
J Biomater Sci Polym Ed. 1994;6(1):1-13. doi: 10.1163/156856295x00715.
The immobilization of heparin onto polymeric surfaces using hydrophilic spacer groups has been effective in curtailing surface induced thrombus formation. In this study, the effect of hydrophilic spacers (PEO) on the binding kinetics of immobilized heparin with antithrombin III (ATIII) and thrombin was investigated. Monodispersed, low molecular weight heparin was fractionated on an ATIII affinity column to isolate high-ATIII affinity heparin. This high-ATIII affinity fraction was immobilized onto a styrene/p-amino styrene random copolymer surface using hydrophilic poly(ethylene oxide) (PEO) spacer groups. Styrene/p-amino styrene random copolymer was chosen as the model surface to provide quantitative and reproducible surface concentrations of available amine groups, grafted PEO spacers, and immobilized heparin. The polymer substrate was coated onto glass beads, tolylene diisocyanate modified PEO was covalently coupled to the surface, followed by heparin immobilization. The bioactivity of immobilized heparin was 16.2%, relative to free heparin, and a 1:1 binding ratio between heparin and PEO was achieved. The binding of ATIII and thrombin to control surfaces (no heparin), soluble heparin, heparin immobilized directly onto the surface, and heparin immobilized via spacer groups, were compared. Soluble heparin bound both thrombin and ATIII, while heparin immobilized directly onto the surface bound only thrombin. Spacer-immobilized heparin bound both ATIII and thrombin, although to a lesser extent than soluble heparin. Thus, the enhanced bioactivity of spacer-immobilized heparin, compared to direct-immobilization, may be attributed to the retention of ATIII binding.
使用亲水性间隔基团将肝素固定在聚合物表面，在减少表面诱导的血栓形成方面已取得成效。在本研究中，研究了亲水性间隔基团（聚环氧乙烷）对固定化肝素与抗凝血酶III（ATIII）和凝血酶结合动力学的影响。将单分散的低分子量肝素在ATIII亲和柱上进行分级分离，以分离出高ATIII亲和力的肝素。使用亲水性聚（环氧乙烷）（PEO）间隔基团将这种高ATIII亲和力级分固定在苯乙烯/对氨基苯乙烯无规共聚物表面。选择苯乙烯/对氨基苯乙烯无规共聚物作为模型表面，以提供可用胺基团、接枝的PEO间隔基团和固定化肝素的定量且可重复的表面浓度。将聚合物底物涂覆在玻璃珠上，将甲苯二异氰酸酯改性的PEO共价偶联到表面，随后进行肝素固定。相对于游离肝素，固定化肝素的生物活性为16.2%，并且肝素与PEO之间实现了1:1的结合比例。比较了ATIII和凝血酶与对照表面（无肝素）、可溶性肝素、直接固定在表面上的肝素以及通过间隔基团固定的肝素的结合情况。可溶性肝素与凝血酶和ATIII都结合，而直接固定在表面上的肝素仅与凝血酶结合。间隔基团固定的肝素与ATIII和凝血酶都结合，尽管程度小于可溶性肝素。因此，与直接固定相比，间隔基团固定的肝素生物活性增强可能归因于ATIII结合的保留。
