Objective: To prepare hierarchically structured fibrous scaffolds with different morphologies, and to explore the additional dimensionality for tuning the physicochemical properties of the scaffolds and the effect of their hemocompatibility and cytocompatibility.
Methods: Electrospinning poly (e-caprolactone) (PCL)/polyvinylpyrrolidone (PVP) bicomponent fibers (PCL∶PVP mass ratios were 8∶2 and 5∶5 respectively), and the surface porous fibrous scaffolds were prepared by extracting PVP components. The scaffolds were labeled PCL-P8 and PCL-P5 respectively according to the mass ratio of polymer. In addition, shish-kebab (SK) structured scaffolds with different kebab sizes were created by solution incubation method, which use electrospun PCL fibers as shish while PCL chains in solution crystallizes on the fiber surface. The PCL fibrous scaffolds with smooth surface was established as control group. The hierarchically structured fibrous scaffolds were characterized by field emission scanning electron microspore, water contact angle tests, and differential scanning calorimeter (DSC) experiments. The venous blood of New Zealand white rabbits was taken and hemolysis and coagulation tests were used to characterize the blood compatibility of the scaffolds. The proliferation of the pig iliac artery endothelial cell (PIEC) on the scaffolds was detected by cell counting kit 8 (CCK-8) method, and the biocompatibility of the scaffolds was evaluated.
Results: Field emission scanning electron microscopy showed that porous morphology appeared on the surface of PCL/PVP bicomponent fibers after extracting PVP. In addition, SK structure with periodic arrangement was successfully prepared by solution induction, and the longer the crystallization time, the larger the lamellar size and periodic distance. The contact angle and DSC measurements showed that when compared with smooth PCL fiber scaffolds, the crystallinity of PCL surface porous fibrous scaffolds and PCL-SK fibrous scaffolds increased, while the hydrophobicity of PCL-SK fibrous scaffolds increased, but the hydrophobicity of PCL porous scaffolds did not change significantly. The hemolysis test showed that the hemolysis rate of PCL surface porous fibrous scaffolds and PCL-SK fibrous scaffolds was higher than that of PCL fibrous scaffolds. According to American Society of Materials and Tests (ASTM) F756-08 standard, all scaffolds were non-hemolytic materials and were suitable for blood contact materials. Coagulation test showed that the coagulation index of PCL surface porous fibrous scaffolds and PCL-SK fibrous scaffolds was higher than that of PCL fibrous scaffolds at 5 and 10 minutes of culture. CCK-8 assay showed that both hierarchically structured fibrous scaffolds were more conducive to PIEC proliferation than PCL fibrous scaffold.
Conclusion: Based on electrospinning technology, solution-induced and blend phase separation methods can be used to construct multi-scale fiber scaffolds with different morphologies, which can not only regulate the surface physicochemical properties of the scaffolds, but also have good blood compatibility and biocompatibility. The hierarchically structured fibrous scaffolds have high application potential in the field of tissue engineering.
目的: 构建不同形貌的多尺度纤维支架，探究不同形貌结构对支架物理性能及血液和细胞相容性的影响。.
方法: 静电纺聚己内酯［poly（ε-caprolactone），PCL］/聚乙烯吡咯烷酮（polyvinylpyrrolidone，PVP）双组分纤维（PCL∶PVP 质量比分别为 8∶2 和 5∶5），并通过浸提 PVP 组分制备表面多孔纤维支架，根据聚合物质量比分别标记为 PCL-P8、PCL-P5。另外采取溶液诱导结晶方式在 PCL 纤维表面形成串晶结构（shish-kebab，SK），调控结晶时间制备不同尺寸的 PCL-SK 纤维支架。以表面光滑的 PCL 纤维支架作为对照，取两种不同纤维形貌的 PCL 多尺度纤维支架，采用场发射扫描电镜、接触角测试、差示扫描量热仪（differential scanning calorimeter，DSC）进行性能表征；取新西兰大白兔静脉血，采用溶血和凝血实验表征支架的血液相容性；采用细胞计数试剂盒 8（cell counting kit 8，CCK-8）法检测猪髂动脉内皮细胞（pig iliac artery endothelial cell，PIEC）在支架上的增殖情况，评价支架的生物相容性。.
结果: 场发射扫描电镜观察显示 PCL/PVP 双组分纤维提取 PVP 后，表面出现多孔形貌；此外，通过溶液诱导成功制备出呈现周期排列的 SK 结构，且结晶时间越长，片晶尺寸和周期距离越大。接触角和 DSC 检测示，与表面光滑的 PCL 纤维支架相比，PCL 表面多孔和 PCL-SK 纤维支架的结晶度增加，PCL-SK 纤维支架疏水性增加，而 PCL 表面多孔纤维支架的疏水性无明显变化。溶血实验显示，PCL 表面多孔和 PCL-SK 纤维支架的溶血率均高于 PCL 纤维支架，根据美国材料与试验协会（ASTM）F756-08 标准评价，所有支架均为非溶血材料，均适用于血液接触型材料。凝血实验显示培养 5、10 min 时，PCL 表面多孔和 PCL-SK 纤维支架的凝血指数均高于单纯 PCL 纤维支架。CCK-8 法检测示两种多尺度纤维支架均比 PCL 纤维支架更有利于 PIEC 增殖。.
结论: 以静电纺技术为基础，采用溶液诱导和共混物相分离方法可以构建不同形貌的多尺度纤维支架，不仅可以调控支架的表面物理化学性能，且多尺度纤维支架具有良好的血液和生物相容性，在组织工程领域具有较高的应用潜能。.
Keywords: Hierarchically structured fibrous scaffold; cell proliferation; hemocompatibility; porous surface; shish-kebab structure.