Preparation Of Oriented Ordered Hydroxyapatite Fibers And Characterization Of Their Morphology And Properties

Hydroxyapatite(Ca10(PO4)6OH2,HA)is the main inorganic component of human bones and teeth and is widely used in bone tissue engineering for its excellent biocompatibility,bioactivity,and osteoinductive properties.Its low specific gravity and high-temperature resistance also make it a promising material for industrial applications.However,the poor mechanical properties of conventional block HA materials have led to their use in nondynamically loaded applications in the form of three-dimensional scaffolds.The single threedimensional block form is difficult to meet the specific needs of practical applications,and the one-dimensional form of HA fibers is relatively easier to design and optimize for excellent application properties,which is one of the current hot topics of research in the field of biomaterials.In this study,HA fibrous materials with ordered orientation were prepared by both wet extrusion and solvent heat methods,and the products were characterized physicochemically and mechanically.The one-dimensional HA/polymer composites were prepared by injection molding in wet extrusion,and the state and property changes of different polymers(both oleic acid and chitosan/gelatin combinations)combined with HA nanofibers were investigated.SEM,XRD,FTIR,TGA,and mechanical studies were used to characterize the products of HA synthesis in different proportions.The results show that the ratio of HA nanofibers to organic matter has a profound effect on the physical,chemical,and mechanical properties of the composites.The desired properties are more likely to be obtained when the proportion of HA nanofibers in the composite reaches 70%.Meanwhile,the stability conditions of hydroxyapatite(HA)suspensions were analyzed using zeta potential and DLVO theory,and the results showed that a solid content of no more than 2%could ensure the stability and dispersion of the mixed suspensions.In the investigation of the effect of carbonate content on the morphology and properties of one-dimensional HA fiber products prepared by the solvothermal method,HA materials with different morphology and phase composition were synthesized in the solvothermal reaction system by controlling the carbonate addition and using oleic acid as a template.When the carbonate content reached 0.004 mol and[OH-]/[CO32-]=10,the reaction system produced oriented and ordered HA nanofibers in clusters.The product has good flexibility and certain mechanical strength,mimicking the arrangement of inorganic materials in human bones,and has a high potential for application.The effects of ionic interference and charge balance(CO32-,OH-,PO43-,Na+,Ca2+)on the microstructure,phase composition,and thermal stability of HA nanofiber bundles in the solvothermal system during the chemical reaction were further investigated based on TEM,TGA,DSC,and other characterization and analysis results.The mechanism of formation and assembly of HA nanofibers is proposed and the role of van der Waals forces in this process is discussed.In the investigation of the effect of hydroxide content on the morphology and properties of 1D HA fiber products prepared by the solvothermal method,HA materials with different morphology and phase composition were synthesized in the solvothermal reaction system by controlling the amount of hydroxide addition,and the microscopic morphology of the reaction products was characterized and analyzed by TEM,TGA and DSC tests,in which the morphology and arrangement of the nanofibers,the changes in lattice,cell,and crystallinity compared to the normal products,were compared and differentiated from the carbonate ions.