Preparation and characterization of the silk fibroin/ hydroxyapatite composites

In order to improve hydroxyapatite ( HAP) brittleness and osteo -inductivity , HAP was prepared usingthe co-precipitation method. Silk-fibroin (SF) was obtained by salt-resolving. The SF/ HAP composite was derivedby mixing HAP sols with SF sols. The phase composition and morphology of HAP and SF/ HAP composites wereinvestigated using X-ray diff raction (XRD) , scanning elect ron microscopy (SEM) and Fourier inf rared spect roscopy( FIR) . The compressive st rength 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 result s show that HAPmixes with SF in the SF/ HAP composites at the nano-scale. The SF in the SF/ HAP composites mainly has the typical silk Ⅱconformation (β-sheet) . The pect ral peak of acyl Ⅴofβ-sheet conformation disappears and the positionsof the other spect ral peaks ofβ-sheet conformation in the SF/ HAP composites are changed , which indicates that thechemical 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 st rength of the SF/ HAP compositesreaches 63 MPa. It is clear that the SF/ HAP composite is a desirable biomedical material for the repairing of bonedefect s with an excellent bioactivity , osteo-inductivity and high mechanical st rength.