Abstract：
Sodium alginate (SA)-based implantable scaffolds with slow-release drugs have become increasingly important in the fields of biomedical and tissue engineering. However, high-molecular-weight SA is difficult to remove from the body due to the lack of SA-degrading enzymes. The very slow degradation properties of SA-based scaffolds limit their applications. Herein, we designed a series of biodegradable oxidized SA (OSA)-based scaffolds through amide bonds, imine bonds and hydrogen bridges between OSA and silk fibroin (SF). SF/OSA-0.4 with a blend ratio of 4/1 was chosen for further polydopamine (PDA) surface modification studies through the optimization of those parameters such as different OSA oxidation degrees, and blend ratios. PDA modified SF/OSA-0.4 (Dopa/SF/OSA-0.4) showed the excellent stability, better stretchable properties, a uniform interconnective porous structure, high thermal stability, a low hemolysis ratio and cytotoxicity. In vitro degradation experiments showed that the degradation rate of SF/OSA was significantly higher than that of SF/SA, but the degradation slowed again after PDA modification. Interestingly, the degradation of Dopa/SF/OSA-0.4 in vivo was significantly faster than that in vitro. Dopa/SF/OSA-0.4 was also more conducive to new tissue growth and collagen bundle formation. Moreover, Dopa/SF/OSA-0.4 improved the absorbability of RhB (model drug) and reduced the sudden release of RhB during the sustained release.
摘要：
基于海藻酸钠（SA）的具有缓释药物的可植入支架在生物医学和组织工程领域变得越来越重要。然而,由于缺乏SA降解酶,高分子量的SA难以从体内除去。基于SA的支架的非常缓慢的降解特性限制了它们的应用。在这里，我们通过酰胺键设计了一系列可生物降解的氧化SA（OSA）支架，OSA和丝素蛋白（SF）之间的亚胺键和氢键。选择混合比为4/1的SF/OSA-0.4进行进一步的聚多巴胺（PDA）表面改性研究，通过优化这些参数，例如不同的OSA氧化程度，和混合比。PDA修饰的SF/OSA-0.4(Dopa/SF/OSA-0.4)显示出优越的稳固性,更好的可拉伸性能，一个统一的相互联系的多孔结构，热稳定性高,低溶血率和细胞毒性。体外降解实验显示，SF/OSA的降解率显著高于SF/SA，但PDA修改后退化速度再次减慢。有趣的是,Dopa/SF/OSA-0.4在体内的降解明显快于体外。多巴/SF/OSA-0.4也更有利于新组织生长和胶原束形成。此外，Dopa/SF/OSA-0.4改善了RhB（模型药物）的吸收性，并减少了持续释放过程中RhB的突然释放。
