| It is well known that silk fibroin protein is important natural protein obtained from silkworm silk, it consistis of 18 kinds of amino acid. Silk fibroin is a polymer material with the properties of innocuity, non-polluting, non-stimulating effect, biodegradable and superior biocompatibility. Silk fibroin as a bio-medical textile materials, has owned broad and deep application in the biomedical field and become one of the study objects for tissue engineering scaffolds in recent years.The research group took medical applications as the background, chooses the silk fibroin as an organic phase ,which is with excellent biocompatibility for cartilage tissue engineering seed cells , and tried to combineβ-wollastonite with a good induction for bone as inorganic phases,prepared silk fibroin/β-wollastonite composite porous scaffolds, and studied the structure and properties to broaden its application prospects in bone repair and tissue engineering.The main work and conclusions are listed as follows:1. The silk fibroin/β-wollastonite composite porous scaffolds were successfully prepared through using the blend and freeze-drying method under controlling the conditions .2. The surface morphology, porous structure and pore wall`s microstructure of the silk fibroin/β-wollastonite composite porous scaffolds were characterized by using SEM,FTIR,XRD. The effect ofβ-wollastoniton causing the conformation change of silk fibroin was studied and these results were showed as follows:(1)The SEM results indicated that by freeze-drying, the pores of the silk fibroin /β- wollastonite composite porous scaffolds were linked to each other, and the shape of these pores were irregular polygonal and distributed uniformly. The porosity was from 83~ 87%,, and average pore diameter was from 100 ~ 300μm. The composite scaffold remained good structure,β-wollastonite was dispersed uniformly in the pore walls and formed the type of organic/inorganic network structure.(2)The XRD and FTIR analysis implied that the formation ofβ-wollastonite particles might induce the conformational transition of silk fibroin from the typical Silk I to the typical Silk II structure partly .Because in aqueous solution the group in silk fibroin protein molecules andβ-wollastonite formed intermolecular hydrogen bonds and complex micro-structure, that promoted the secondary structure of silk fibroin changed from the random toβ-sheet structure in part.3. The mechanical properties, thermal properties, water absorption and hydrophilic properties of silk fibroin/β-wollastonite composite porous scaffolds were measured, and discussed the impact of composite properties by addingβ-wollastonite, these results had been studied as follows:(1)Mechanical performance test showed that pure silk fibroin scaffolds were in poor mechanical properties, compared with pure silk fibroin scaffold material, the compressive modulus and compressive strength of composite scaffolds had an obvious improvement, and the more ratio ofβ-wollastonite were added, the better mechanical properties were showed.(2)TGA and DTG thermal analysis showed that the initial decomposition temperature of composite scaffold in different proportions had increased compared to pure silk fibroin scaffold.The result indicated that the change was mainly becauseβ-wollastonite caused the silk fibroin protein conformation transformation and increased the thermal stability.(3)Hydrophilic properties and water absorption tests showed that composite porous scaf- folds showed better performance than pure silk fibroin scaffold, due to the good hydrophilicity withβ-wollastonite improved the water absorption properties of composite scaffolds .4. The silk fibroin/β-wollastonite composite porous scaffolds were used to experiments in vitro biological activity in simulated body fluid (SBF), in vitro degradation in Tris-HCl buffer and cell culture,and results were showed as follows:(1)In vitro bioactivity tests by SBF showed that silk fibroin/β-wollastonite composite porous scaffolds can quickly induce carbonated hydroxyapatite (CHA ) deposited on scaffolds surface after immersion in SBF for 1 days,when soaked after 3 days, a large number of CHA particles layer deposited on the surface in composite scaffolds by XRD, FESEM and EDS,which were in the similar morphology and structure with hydroxyapatite in natural bone. The results showed that the composite scaffold had good in vitro bioactivity, and improved the bioactivity of pure silk fibroin obviously.(2)In vitro degradation behavior showed that silk fibroin/β-wollastonite composite porous scaffolds immersed in Tris-HCl buffer after 10 weeks , the degradation rate was up to 41.64% and pH value was maintained at 7.35,which avoided the sharp decline of pH by acid degradation composition for pure silk fibroin . The result indicated that the composite scaffolds had good degradability.(3)The cell culture experiment indicated that on the silk fibroin/β-wollastonite composite porous scaffolds osteoblasts cell had better attachment,proliferation and Alkaline phosphate activity than pure silk fibroin scaffold,which may beβ-wollastonite had played an important role in cell proliferation. The experiment showed composite scaffolds had good biocompatibility.Above all,these results indicated that the silk fibroin/β-wollastonite composite porous scaffolds,prepared by blend and freeze-drying method, showed many excellent characteristics, such as good hydrophilicity, degradability, well bioactivity and fine biocompatibility. The composite porous scaffold was not only can adjust the mechanical properties to match with the bone tissue, but also can enhance the bonding capacity between silk fibroin protein and bone tissue.This provided reference and new methods for silk fibroin material to apply in bone tissue repair and tissue engineering in future.
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