| Tissue engineering is first to mimic the fibril structure and composition of the extracellular matrix (ECM) that provides essential guidance for cell organization, survival and function, and then to develop feasible substitutes to aid in the clinical treatment. The basis of this study is to develope the functional scaffolds. The present focus of the tissue engineering scaffolds is to selectively process a variety of natural and synthetic polymers into a nanofibrous scaffold according to the characteristics of ECM proteins ranging in diameter from 50nm to 500nm. However, it's difficult for the traditional spinning methods to produce the fibers less than 10um. At present, three distinct techniques have proven successful in routinely creating such scaffolds: self-assembly, phase separation and electrospinning. Compared with the other two techniques, electrospinning, which is cost effective, can prepare long continuous and aligned nanofibers; and tailor mechanical properties, size, shape, so this technology has wide applications and shows broad industrialization prospects.As a protein-based polymer, SF has been paid much attention by the biomedicine and materials researchers. Based on this reason, the main aim of this research is to develop SF-based nanofiber scaffolds for tissue engineering. Scaffold should have excellent mechanical properties, dimensional stability, high porosity and biocompatibility; therefore, in order to improve spinnability and biological properties, SF and gelatin were first blended and electrospun. After that, PLA was electrospun on the SF-gelatin nanofiber layer, and thus obtain PLA/SF-gelatin composite fiber scaffolds with good biocompatibility, high dimensional stability and excellent mechanical properties.In this paper, the compatibility between silk fibroin and gelatin was firstly examined and analyzed by means of FTIR, DTA and SEM, and then its blending electrospinning was researched. Secondly, we investigated the feasibility to construct the composite PLA/SF-gelatin scaffold, analyzed the interaction and its principle. After that, the composite PLA/SF-gelatin membrane was successfully prepared by multi-layering electrospinning, and then its biological properties in vitro and in vivo were evaluated; Finally, we made the composite PLA/SF-gelatin tubular scaffold , and hope it can be used for vascular tissue engineering.The results showed that SF and gelatin has good compatibility. Under the technical parameters of 11wt%, SF/Gelatin (70/30) , spinning solution, electrode distance 13cm and voltage 22kv,the electrospun SF-gelatin nanofiber had the narrower diameter distributions and the diameter reached 83.9nm. In addition, the best electrospinning parameters for PLA were concentration 5%, voltage 25kV, polar distance 15cm, flow of 0.1ml/h, the fiber diameter reached 1342nm.The results also proved SF- gelatin blend nanofiber membrane demonstrated high dissolvability, the strength was low and flexibility was poor. By ethanol treatment for 60min, the breaking intensity and initial modulus increased significantly. In addition, the nanofiber membrane can support the growth of human umbilical endothelial cells, but the scaffold was brittle after the treatment, and the dimensional stability was bad. PLA/ SF-gelatin composite fiber membrane achieved both a higher strength (0.43-0.65 MPa), but also good flexibility (elongation up to 12.4-19.5%). The breaking tenacity reached 1.98-1.51MPa and the elongation was 7.12-7.30% after chemical treatment, which was higher than that of the chemically treated SF-gelatin fiber membrane. The dimensional stability of PLA/SF-gelatin composite fiber membrane was better than the electrospun SF-gelatin fiber membrane, moreover, the dissolubility decreased. Although the porosity of PLA/SF-gelatin composite fiber membrane was lower than that of the SF-gelatin membrane, which still had high porosity and thus increased the migration and growth.The interface can be formed between PLA and SF-gelatin layers by mutual insertion, physical adsorption and covalent bond, which caused the synergistic effect and then inhibited the shrinkage of SF-gelatin layer, improving the dimensional stability and flexibility. As a result, the breaking tenacity of PLA/SF-gelatin composite tubular scaffold was 1.28- 1.31MPa, the elongation reached 41.11% (4.5mm) and 37.5% (6mm), the bursting strength was 110kPa, and the suture strength was more than 1.0N/needles, which was up to the standard for vascular grafts. After chemical treatment, the breaking tenacity increased to 212.7kPa (4.5mm) and 198.6kPa (6mm), which was close to human saphenous vein pressure.The electrospun SF-based nanofiber membrane could support 3T3 fibroblast growth and proliferation, the hemolysis rate was less than 5% and thus it could not cause the hemolysis; the short-term subcutaneous implantation test showed that the minor inflammatory reactions surrounding the scaffolds, no significant difference. Together with mechanical properties, dissolvability and biological properties, PLA-SF/gelatin (70:30) composite nano-fiber membrane is more suitable for cell scaffolds, so the PLA-SF/gelatin (70:30) composite tubular scaffold demonstrated the enormous potential for vascular tissue engineering.
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