The Study Of Regenerated Antheraea Pernyi/Bombyx Mori Silk Fibroin Blend Porous Materials

In recent years, the unique chemical and mechanical properties of Bombyx mori (B. mori) silk fibroin have made this protein polymer highly attractive for biomedical uses. However, the Antheraea pernyi (A. pernyi) silk fibroin containing the tripeptide sequence Arg-Gly-Asp (RGD), which is known to exhibit specific interactions with mammal cells, has better biocompatibility than B. mori to provides significant feasible proofs for staring silk fibroin-based tissue healing engineering scaffolds, artifical skin and tissue inducing materials. This paper takes a systemic research on the structure, properties and biocompability of the regenerated A.pernyi/B.mori blend porous materials as well as effect on the defect of dorsum of sprague-dawley (SD) rats.The A.pernyi/B.mori silk fibroin blend solutions were chemically cross linked of 20% EDC, 10% NHS and 20% MES (relative to total silk fibroin quantity), whose mixed ratios were 100/0, 80/20, 60/40, 40/60, 20/80 and 0/100, respectively. The blend porous materials were prepared by freeze-drying, which freezing the mixture solutions on -80 oC, -60 oC, -40 oC and -20 oC, respectively. By means of X-ray diffraction and FT-IR spectroscopy, the molecular conformation of the crosslinked and uncrosslinked A.pernyi/B.mori silk fibroin blend porous materials which prepared from diffierent mixed ratios. The results showed that the content of random coil andα-helix structures in the blend porous materials decreased as the content of B.mori silk fibroin increased, as well as moreβ-sheet structure was formed in the porous materials after crosslinked. The thermal stability of blend porous materials prepared by different mixed ratio was examed by means of DTG analysis, the results showed that the thermal stability of blend porous materials being stronger as the content of A.pernyi silk fibroin increased, and crosslinked porous materials is more thermal stable than uncrosslinked ones. The compressibility, expansivity, water solubility, pore size, porousity and pore density of blend porous materials prepared from different condition were investigated. The outcome indicated that compressibility, water solubility and expansivity being smaller as the content of B.mori silk fibroin increase when freezing at the same temperature; the compressibility, water solubility and expansivity being larger as the freezing tempareture rise if they have the same mixed ratio. When the content of B.mori silk fibroin increased and the freezing temperature drop, the pore size being smaller and the pore density being larger.The attachment, spreading, proliferation and morphology of L929 cell on the A.pernyi/B.mori silk fibroin blend film and porous materials were observed after cells have been seed for 1d, 3d, 5d, 7d and 9d by microscopy and MTT. The results showed that the proliferation of cells on A.pernyi silk fibroin was stronger than that of B.mori silk fibroin and collagen, the proliferation of cells on the blend film were all between the A.pernyi silk fibroin and B.mori silk fibroin. The results from confocal microscopy observation indicated that cells proliferate better on EDC crosslinked A.pernyi silk fibroin porous materials than on PVA scaffold. The MTT value of cells on porous matrial was bigger than that of film as their has the same ratio of A.pernyi silk fibroin and B.mori silk fibroin at the same cultured time.The animal model used here was sprague-dawley (SD) rats with a 20-mm×20-mm gap defect in the. The defects were repaired using A. pernyi silk fibroin porous materials and B.mori silk fibroin porous materials in experimental group, while the PVA scaffolds as negative group. The recovery of the defect dorsum was evaluated postoperatively at the 5th, 10th, 15th, and 25th day using macroscopic, histological and immunohistochemical. In vivo, at 10 days after implantation, morphological results showed that neo-blood vessel were formed in the boundary of the silk fibroin porous materials and PVA scaffold, and neo-blood vessel became more as the time increase. Immunohistochemical results showed that A. pernyi silk fibroin porous material and B.mori silk fibroin porous material have low immunogenicity, and can support histo-regeneration of defect dorsum of SD rats.