Design Of Fiber Reinforced Silk Fibroin Scaffolds And Application In Biological Tissue Repair Materials

Nowadays, silk has been expanded the scope of application from the traditional textile materials to biological materials and was widely used in tissue engineering, because of its superior strength, good biocompatibility and biodegradability. However, compared to native silk, the regenerated silk fibroin biomaterials, with poor biomechanical properties, could not satisfy the requirements of physiological activity and transplant, resulting in the fracture of materials. Considering that the performance of silk materials mainly depended on their nano-assembly structures. Using the excellent mechanical properties of silk fibers or regulating the nanostructures of silk is preferred to improve the strength of silk fibroin scaffolds for specific applications in tissue engineering.Here, based on the structure and mechanical characteristics of natural blood vessels under physiological conditions, the inner and middle layers were fabricated by electrospinning silk fibroin(SF) and poly(L-lactic acid-co-ε-caprolactone)(PLCL) were tuned sequentially at different SF/PLCL ratios, providing similar mechanical properties to native blood vessels. Degummed silk–reinforced outer layer was used to withstand high pressure. Mechanical properties of the small diameter vascular grafts were investigated and compared to those of native blood vessels. Then the vascular grafts achieved good satisfied biomechanical property as native blood vessels. In vitro tests showed a good cytocompatibility and the small diameter vascular grafts represent a suitable candidate for small diameter vascular replacement.Based on silk fibroin nano-assembly mechanism, we controlled the mechanical properties by adjusting the silk nanostructure. Firstly, we got silk fibroin nanofibers solution by controlling the concentration rate and temperature. We then added the nanofibers to silk fibroin solutions to prepare anisotropy scaffolds under the electric field. When the total silk fibroin concentration of mixed system was 2%, the contents of silk fibroin nanofiber would effect structure and mechanical properties of the anisotropic scaffold. The anisotropic scaffold with 1:1 ration nanofiber solution to silk fibroin solution showed the best mechanical properties. When the total silk fibroin concentration of mixed system was 7%, with the increasing contents of silk fibroin nanofiber dramatically affected the orientation and mechanical properties of anisotropic scaffold.Overall, we fabricated a three-layers small diameter vascular graft with excellent mechanical properties and good cytocompatibility by combination braiding and electrospinning. Besides, we achieved controlled construction and mechanical properties anisotropy scaffolds by adjusting the mixing ratios and concentration of silk fibroin solution with different nanostructures.