Study On Functionalized Nano Selenium/Electrospun Nanofiber Composite Preparation And Application In Bone Tissue Repair

Bone tissue repair scaffold provides a promising strategy for large bone defects.Scaffolds for bone repair are facing two challenges: one is that scaffolds should have enough osteoinductive ingredients to promote bone regeneration,the other is to support remodeling of blood vessels in bone tissue to avoid ischemic osteonecrosis.In view of the clinical needs,biomimetic scaffolds have been developed to improve the histocompatibility and bone repair.Compared with other scaffolds,electrospun fiber scaffolds have a similar structure to natural extracellular matrix(ECM)and have unique application advantages in bone repair.However,in order to achieve effective bone repair,the coordination of bioactive components and angiogenic factors should be considered.Therefore,based on the need of bone repair,combined,it is an important strategy to construct a kind of composite scaffold material with the specific topological structure of the fibril scaffold,which can regulate cell behavior,then to promote bone formation and vascularization.It is the development trend of scaffold to realize more comprehensive and efficient function for bone repair through combining with chemistry,biology,material engineering and other disciplines to develop scaffold material system.More experimental research on the internal relationship between the components in a material system is needed.Therefore,a new fibril composite loaded with nano selenium was developed in this research.Firstly,the fibril scaffold with good biocompatibility was prepared by electrospinning,then the functionalized nano selenium was desposited on the surface of the scaffold,to construct the bioactive surface with specific topological morphology,which could effectively regulate the behavior of stem cells and endothelial cells.It is hoped that the improvement of the differentiation of stem cells and the migration of endothelial cells can promote osteogenesis and vascularization.The specific research contents are as follows,(1)Preparation of polycaprolactone(PCL)/Gelatin fiber scaffold and its regulation on cell morphologyPorous fiber scaffold with different PCL/Gelatin mass ratio were prepared by electrospinning.The effects of different PCL/Gelatin mass ratio on the morphology,surface wettability,mechanical properties and in vitro degradation of scaffold were studied.Also,the effects of PCL/Gelatin mass ratio and electrospinning voltage on fiber orientation were studied.Results show that the oriented fiber structure can effectively guide the orientation of cells,whcih can be applied to the repair of specific tissues,such as bone tissue,nerve tissue and so on.(2)Regulation of stem cell differentiation by the polycaprolactone/Gelatin loaded with functionalized nano selenium composite fibril scaffoldDesign,synthesize and characterize EGCG@Se nanoparticles.Then EGCG@Se were surface immobilized on fiber by direct deposition to obtain P/G-EGCG@Se composite.By adjusting the deposition concentration of Se,the fibril composite with different chemical composition and surface morphology were obtained.The Se content of fibril composite from high to low named P/G-EGCG@Se-5,P/G-EGCG@Se-4,P/G-EGCG@Se-3,P/G-EGCG@Se-2 and P/G-EGCG@Se-1.Study the effects of surface chemical composition and surgace morphology of fibril composite materials on the adhesion,proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells(MSCs).Results showed that the relatively lower content of Se was more conducive to the adhesion,proliferation and osteogenic differentiation of MSCs.At the same time,EGCG could synergistically promote the osteogenic differentiation,upregulating bone specific gene expression and increasing calcium deposition.In addition,moderate sueface morphology can promote the adhesion of MSCs.(3)Regulation of endothelial cell behavior by the polycaprolactone/Gelatin loaded with functionalized nano selenium composite fibril scaffoldStudy P/G-EGCG@Se fibril composite effects on endothelial cell behavior.Results showed that when Se content was relatively low(down to P/G-EGCG@Se-2),the combination of Se and EGCG,integrating certain surface morphology can most effectively promote the endothelial cell spreading,and then promote the cell migration.In conclusion,combined with chemical and physical factors,this work can improve the surface bioactivity of fibril composite,which can be applied to bone tissue repair,promote bone formation and angiogenesis.