Preparation And Biological Properties Of Heterogeneous Coaxial Collagen Fiber Materials

Bone repair materials are one of the most widely used biomedical materials with the greatest actual demand at present.The development of ideal bone repair and bone replacement materials has become an important research direction in clinical medicine and biomaterials.Compared with synthetic materials,biomimetic bone repair materials based on collagen and hydroxyapatite have obvious advantages such as good biocompatibility and induction of bone regeneration,which is one of the most important directions in the research and development of bone repair materials.The polymer-induced liquid phase precursor theory(PILP)biomimetic mineralization is the mainstream model for the preparation of collagen/calcium phosphate biomimetic bone repair materials.However,there are still some significant defects,such as low salinity,low binding degree of mineralized products and collagen,and great difference between the structure of mineralized products and natural bone.Therefore,on the basis of PILP biomimetic mineralization strategy,this paper attempts to adopt a new drop mineralization process and in situ mineralization on collagen fiber recombination gel to explore new means of preparing bone repair materials,further improve material properties and enhance the degree of biomimetic mineralization of products.The main research contents are as follows:(1)Selection and optimization of mineralization processPreparation of collagen fiber for raw material with bovine tendon collagen restructuring gel,polyacrylic acid(PAA)as inducers,by drops of higher concentration of calcium and phosphate ions solution,in situ mineralization in collagen fiber reorganization of the gel,and joining methods,addition amount of PAA and calcium chloride solution and potassium hydrogen phosphate solution to join for the amount of speed and main process parameters optimization.The results of transmission electron microscopy showed that the collagen fibers could be mineralized by in-situ addition of calcium and phosphate ions on the collagen fibers.The results of XRD and IR analysis show that the inorganic phase of the mineralized products prepared by this method basically exists in amorphous form.The results of thermogravimetric analysis show that the biomimetic mineralized products have high mineralization rate.The results of optimization of process parameters showed that the optimum mineralization effect was obtained when adding 10 mg PAA directly,controlling the adding rate of calcium chloride and dipotassium hydrogen phosphate to 70?L/h and adding amount of calcium chloride and dipotassium hydrogen phosphate to 1.5m L /h.(2)Study on the influence of static pressure on mineralization behavior and effectOn the basis of the research on the optimization of mineralization process and conditions,static pressure was further introduced as the regulation means of mineralization behavior to explore the influence of static pressure field on the biomimetic mineralization behavior of collagen/calcium phosphate and the structural properties of the products.The results of transmission electron microscopy and scanning electron microscopy showed that free calcium ions and phosphate ions were easy to aggregate under pressure,and formed clusters of calcium phosphate,and the degree of crystallization of calcium phosphate was gradually increased with the extension of pressure time.The results of structural and property analysis of the mineralized products show that the addition of pressure will form the crystalline inorganic phase,and with the extension of pressure time,the content and crystallinity of the inorganic phase in the mineralized products will gradually increase,and thus improve the thermal stability,but its swelling ratio and anti-compression ability will be reduced to a certain extent.(3)Influence of crosslinking on mineralization behavior and product propertiesOn the basis of the above research,different cross-linking agents were further introduced into the mineralization process as regulation means to explore the influence of cross-linking on the properties of collagen/calcium phosphate biomimetic mineralization products.The experimental results show that the introduction of different crosslinkers does not change the microstructure of the bionic mineralized products,but the properties of the mineralized products such as pore structure,water absorption,mechanical properties,mineralization degree and thermal stability have different changes.Among them,after cross-linking,the mineralization degree and bearing capacity of the mineralized products will be significantly reduced,but the swelling ratio and thermal stability of the mineralized products are improved.Furthermore,the cell compatibility of the crosslinked mineralized products was systematically evaluated.The results showed that the cell compatibility of the mineralized products was decreased by different crosslinking methods.Compared with glutaraldehyde,the samples cross-linked by EDC-NHS50% and Genipine 100% were more conducive to the growth of cells.