Preparation And Characterization Of Porous Hydroxyapatite/Silk Fibroin Composite Scaffolds

Natural bone is mainly composed of hydroxyapatite (HA) and collagen protein. The synthetic HA is brittle, which does not meet the performance requirement of tissue engineering in the mechanical properties. The collagen extracted the animal always causes the inflammation and other immune responses. On the other hand, Bombyx mori silk fibroin (SF) has wide sources, and its biocompatibility and mechanical properties are all very well. In this work, by biomimicing the composition and structure of nature bone, the porous HA/SF composite scaffolds were fabricated by blending the SF and HA followed by freeze-drying. The morphologies, composition, physical and chemical properties of the composite scaffolds were investigated by SEM, XRD, FTIR and TGA, etc. The results showed that the composite scaffolds had interconnected pores with smooth pore walls and no separation of phases was found. The pore size was ca. 200μm. XRD and FTIR showed that the SF hadβ-sheet conformation. The TG data showed that the SF was decomposited at 310-350℃, much higher than the SF in random structure.In order to improve the osteoblast adhesion and proliferation on the composite scaffolds, we synthesized a silk-RGD fusion protein by gene recombination technology, which was used to modify the pore surface of above composite scaffolds by soaking. The cell lines MG-63 and MC3T3-E1 were used to evalue the cell adhesion, proliferation and differentiation on the composite scaffolds. The results showed that the cell adhesion on the silk-RGD modified scaffolds was higher than that on the control (i.e., unmodified scaffolds), which depended on the concentration of silk-RGD. After being cultured for 7 d in vitro, the cell proliferation rates of MG-63 and MC3T3-E1 increased by 21% and 50%, respectively, compared with the control. For MC3T3-E1 cells, the alkaline phosphatase (ALP) activity data showed an improvement of cell differentiation on the silk-RGD modified scaffolds, but no significant difference was found on the MG-63 cells.Summary, the silk-RGD modified HA/SF composite scaffolds had good biocompatibility, which may be a promising material for the bone tissue engineering.