BACKGROUND:Bionic structure is one of the most important goals of scaffold design in tissue engineering. However, the majority of the bionic scaffolds do not have the capacity of sustained release of growth factors. OBJECTIVE:To fabricate a novel biomimetic nanofibrous heparin/gelatin scaffold and investigate the characterization of the scaffolds including the microstructure, the mechanical strength andin vitro recombinant human bone morphogenetic protein-2 (rhBMP-2) release. METHODS:Heparin-conjugated gelatin was prepared by chemical crosslinking and mixed with gelatin at different ratios. Nanofibrous composite scaffolds with different ratios of heparin-conjugated gelatin (0, 20% and 40%) were fabricated by using a thermaly induced phase separation combined with particle leaching technique. The amount of conjugated heparin in the scaffolds, scaffold microstructures and mechanical strength were detected and observed. The release kinetics of rhBMP-2 from the scaffolds with different concentrations of heparin conjugated gelatin was detected using ELISA method. RESULTS AND CONCLUSION:The composite scaffolds possessed abundant porosities, good mechanical properties, and biomimetic nano-structures. The macroporous size was 250-420 μm. When the ratio of heparin-conjugated gelatin was 0, 20% and 40%, the content of heparin in the scaffolds was 0, (12.82±2.49) and (25.08±3.69) mg/g, respectively, with significant differences; the elastic modulus of the composite scaffolds was (299±38), (286±40) and (236±33) kPa, respectively, with insignificant differences (P > 0.05). With the increase in the content of heparin-conjugated gelatin, the rhBMP-2 adsorption capacity of the nanofibrous heparin/gelatin scaffold is improved, thereby significantly reducing the burst release of rhBMP-2 and prolonging the releasing time.%背景：仿生结构是近年来组织工程支架设计最重要的目标之一，但文献报道的仿生支架多不具有缓释生长因子的能力。 目的：制备新型仿生纳米纤维肝素/明胶复合支架，观察其微观结构、机械强度及对重组人骨形态发生蛋白2的缓释作用。 方法：利用化学交联方法制备肝素化明胶材料，将不同比例的普通明胶和肝素化明胶材料混合，利用热致相分离法和模板成孔技术，制备出含0，20%，40%肝素化明胶的纳米纤维肝素/明胶复合支架。扫描电镜观察新型支架的微观结构，甲苯胺蓝法检测各组支架中的肝素含量，测试支架机械强度，采用ELISA法测定各组支架对重组人骨形态发生蛋白2的释放情况。 结果与结论：①纳米纤维肝素/明胶复合支架有很高的孔隙率，大孔结构250-420μm，孔隙连通度良好，且孔壁具有仿生纳米纤维结构；②含0，20%，40%肝素化明胶的纳米纤维肝素/明胶复合支架中的肝素含量分别为0，(12.82±2.49)，(25.08±3.69) mg/g，3组间比较差异有显著性意义(P<0.05)；③含0，20%，40%肝素化明胶的纳米纤维肝素/明胶复合支架的弹性模量分别为(299±38)，(286±40)，(236±33) kPa，3组间比较差异无显著性意义(P>0.05)；④随着肝素化明胶含量的增加，纳米纤维肝素/明胶复合支架对重组人骨形态发生蛋白2的吸附能力增强，显著降低重组人骨形态发生蛋白2的突释，延长释放时间。
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