Preparation Of Silk Sericin/Hydroxyapatite Composite Bone Scaffold

Bone is the main support of the human body, main storage site of calcium and phosphorus ions. In daily life, bone damage and bone defects are very common, there for hard tissue replacement has been one of the most attrctive aspects of biomedical engineering. Hydroxyapatite(HA), the main mineral composition of bone, has excellent biocompatibility, biological activity, bone conduction characteristics and can form strong bone-bonding with natural bone which make it an ideal bone-repair material. But it also has its own shortcomings, such as a low compressive strength, poor fatigue resistance and bioabsorbancy. Osteoporosis, migration and destruction may occur after implantation, thus limiting the clinic application of hydroxyapatite. Bombyx mori(B.mori) silkworm sericin(SS) is a kind of globular protein extracted from silk, relative molecular mass is 1.4～31.4. It is composed of 18 amino acid, among those Ser(33.43%),Asp(16.71%) and Gly(13.49%) are of high content. SS has excellent phsicochemical characters and superior biocompatibility, so the combination of HA and SS might be a significant hint to develop a good bone substitude material by incorporating the distinctive properties of HA and B.mori SS.In this study, Hydroxyapatite(HA) powder was prepared by coprecipitation of Ca(OH)2 and H3PO4. SS solution was prepared by putting silk in boiled water for 30min.SS/HA composite porous scaffolds with different composite ratios were prepared by means of freeze-drying to simulate the composition and structure of natural bone. Homogeneous SS/HA composite was obtained. SEM pictures showed that HA were evenly distributed in the SS/HA composite porous scaffolds. FTIE and XRD spectra revealed no noticable change in the strucure of SS and HA. In the aspect of mechanics, compression modulus increased with the increase of HA component ratios in the scaffold. But, the pore ratio and mechanical strength of the scaffold were low.