中文摘要：

近年来，基于静电作用的层层自组装技术由于在生物材料的生物相容性表面设计和修饰中具有独特的优点而被广泛研究．用这种技术改性生物材料不仅可以选择合适的生物活性分子（如蛋白质、多糖、DNA等）来调控材料表面生物相容性，而且还可以通过改变组装条件在纳米水平上精细调控涂层性质．大多数自组装多层膜层间存在穿插，降低了层间结构上的规整性，使得静电自组装多层膜表面性质随着组装层数的奇偶变化可能表现出两种性质：一种是体现出各种组装聚电解质性能的交替变化，另一种是由于这种层间穿插而体现出的这两种聚电解质的协同性能．Akashi等研究发现肝素／壳聚糖多层膜，即使致凝血的壳聚糖层朝外时也表现出良好的抗凝血性，他们推测这是由于多层膜中存在分子量较小的肝素迁移到壳聚糖表面造成的．

英文摘要：

The influence of different pH values between assembly and application environment on the surface properties of layer-by-layer assembled heparin and chitosan multilayer films was investigated. The high adsorption amount of cationic dye and high wettability on the chitosan terminated multilayer films at high environment pH may indicate the excess of free sulfate group existed on the chitosan surface. Since the ionization degree of chitosan decreased with increasing of pH, the muhilayer films assembled at low pH will lead to some excess free unpaired der p good sulfate group in higher pH application environment, which paired with ionized amino group unrepared conditions. The blood-compatibility tests performed with these films clearly demonstrated that the anticoagulant activity of low pH assembled heparin/chitosan even on the chitosan-terminated surface. Such an easy and controlled processing by the difference of pH values between assembly and application environment may have a good potential for fabrication of biomedical device coating.