Preparation and characterization of the silk fibroin/hydroxyapatite composites

In order to improve hydroxyapatite(HAP) brittleness and osteo-inductivity,HAP was prepared using the co-precipitation method.Silk-fibroin(SF) was obtained by salt-resolving.The SF/HAP composite was derived by mixing HAP sols with SF sols.The phase composition and morphology of HAP and SF/HAP composites were investigated using X-ray diffraction(XRD),scanning electron microscopy(SEM) and Fourier infrared spectroscopy(FIR).The compressive strength of the SF/HAP composites was also measured.The biological activity of the SF/HAP composites was observed while thermostatic held in simulated body fluid(SBF).The results show that HAP mixes with SF in the SF/HAP composites at the nano-scale.The SF in the SF/HAP composites mainly has the typical silk Ⅱ conformation(β-sheet).The pectral peak of acyl Ⅴ of β-sheet conformation disappears and the positions of the other spectral peaks of β-sheet conformation in the SF/HAP composites are changed,which indicates that the chemical bonds are formed between SF and HAP granules.When the SF/HAP composite is dipped in SBF for eighteen days,the needle-like HAP sheet is formed on the surface.The compressive strength of the SF/HAP composites reaches 63 MPa.It is clear that the SF/HAP composite is a desirable biomedical material for the repairing of bone defects with an excellent bioactivity,osteo-inductivity and high mechanical strength.