Silk Fibroin And Calcium Phosphate Composite Biomaterials Research On Vertebroplasty And Osteochondral Defect Repair

As the increasing number of orthopedic diseases and the development of medical technology,orthopedic tissue engineering gains much more attention since it could provide a new way for therapy.Biomaterials plays an important role in tissue engineering,among them,silk fibroin is a nature polymer with good biocompatibility and plasticity which is being widely used in biomedical,calcium phosphate is also widely used due to its similar chemical constituents to bone.In this study,we aimed on using these two biomaterials to prepare enhanced calcium phosphate cement and tri-layered scaffold for veterbroplasty and osteochondral defect repair.Firstly,silk fibroin solution(SF)were treated by Ca(OH)2 solution to obtain treated silk fibroin solution(tSF),DLS and Zeta potential analysis shows that tSF has larger sized particles and stronger negative potential,FTIR shows that tSF has more random formed silk fibroin chains than that in SF.Then tSF were mixed with calcium phosphate cement(CPC)and thus improved the anti-washout properties and injectability of CPC,more than that,the mechanical properties remarkably enhanced.After characterized on CPCs,we found a more dense structure and higher HA formation in tSF/CPC group.Therefore,we hypothesis the mechanism of the CPC reinforcement that,tSF provided more HA crystal nucleation sites by the negative potential group on its stretched chains,and CPC could transformed into smaller sized HA fast under alkaline environment and binding each other efficiently by SF chains then formed dense structure and increased in conversion rate of HA thus to enhance the mechanical properties of CPCs.Good biocompatibility of tSF/CPC showed in vitro test.The Vertebral body biomechanical experiment shows the tSF/CPC is promising for further application in veterbralplasty.A silk fibroin/hydroxyapatite biomimic tri-layered scaffold that consists of silk fibroin layer,mineralized dense silk fibroin layer and hydroxyapatite layer were prepared.SEM images of the scaffold shows hydroxyapatite layer as bone layer possess interconnecting pores with a size of 300-500 μm.Silk fibroin layer as cartilage layer has a pore size of 100μm and dense silk fibroin layer as mineralized layer possess a dense and oriented structure.Tensile test of scaffold shows the tri-layer scaffold had a strong bonding force between bone layer and cartilage layer and thus to avoid the separation of these two layers.BMSCs attachment on scaffold implied a good biocompatibility of scaffold.The tissue-engineered osteochondral composite group shows good results in rabbit femoral condyle defect repair.