Influence Of Silk Fibroin/Hydroxyapatite Composite On The Properties Of Calcium Phosphate Cement

Objective: To fabricate silk fibroin/hydroxyapatite composite, and add it into calcium phosphatecement to improve the mechanical property, and to evaluate other properties of the modified cement.Methods:1. Fabricate silk fibroin/hydroxyapatite composite by self-assembly of mineralized silkfibroin, and characterize the composite by Fourier transform infrared(FTIR) spectra and X-raydiffractomete（rXRD）.2. Add the composite into the powder phase of calcium phosphate cements at theweight fractions of1%,2%,3%and4%and applying silk fibroin solution as liquid phase. Thecompressive strength of all these cements were measured and compared with calcium phosphate cementapplying deionized water as liquid phase.3. The anti-washout property of CPC applied silk fibroinsolution and deionized water was observed and compared.4. The crystal morphology of the end productof pristine and modified CPC were characterized by XRD, and morphology of the fracture surface wasobserved by scanning electron microscope(SEM).5. Culture the osteoblasts with the extract of materialsand measure the cytotoxicity of silk fibroin and silk fibroin/hydroxyapatite composite by MTT method.Results:1.The pattern of FTIR and XRD reflected that the production was silkfibroin/hydroxyapatite composite.2. The compressive strength of CPC applied DI water as liquid phasewas about31MPa, while applied silk fibroin solution as the liquid phase was about35MPa, andgradually increased to45MPa as the weight fraction of silk fibroin/hydroxyapatite composite increasedfrom1%to3%(p<0.05), and a decrease to about43MPa of compressive strength was observed whenthe weight fraction of silk fibroin/hydroxyapatite up to4%(p<0.05).3. The capability of anti-washoutwas also enhanced when applied silk fibroin solution as liquid phase of cement compared to deionizedwater.4. The XRD pattern shows that adding silk fibroin and silk fibroin/hydroxyapatite into CPC hasno obvious influence on the crystal morphology of the end product.5.In the control test of evaluate thecellular activity by MTT method, no cytotoxicity was observed neither silk fibroin nor silkfibroin/hydroxyapatite composite was added into calcium phosphate cement.Conclusion: Adding3wt%Silk fibroin/hydroxyapatite into CPC has a strengthen effect in the mechanical property of CPC. And applying silk fibroin solution as the liquid phase of CPC can improvethe anti-washout property. The end product does not changed neither silk fibroin nor silkfibroin/hydroxyapatite composite was added into calcium phosphate cement. Meanwhile, nocytotoxicity was observed in cytotoxicity test. More ideal mechanical strength and better anti-washoutproperty expanded the use of calcium phosphate cements.