Construction Of Hydroxyapatite Porous Scaffold With Hierarchical Structure And Its Biological Performance

Hydroxyapatite(HAp)is the main inorganic component of human bone tissue.Because of its good biocompatibility and scaffold system,it can provide cells with a suitable environment for adhesion,proliferation and differentiation,and exhibits excellent bone repair properties.It has attracted much attention in recent years.How to reasonably optimize the HAp scaffold to have good osteogenic activity and antibacterial activity is still facing challenges.Studies have shown that the surface micro-nano structure,pore state and chemical composition of the HAp scaffold have an important influence on its osteogenic performance.This thesis uses the behavior of guar gum in a specific environment to construct a three-dimensional calcium phosphate material system with different dimensions,and uses this as a structural unit to further prepare a three-dimensional porous HAp scaffold with a hierarchical structure.The forming mechanism,physical and chemical properties and biological properties of the scaffold have been systematically studied.The following is the specific content:(1)Construction of guar gum(GG)gel structure based on transition metal hydroxide clusters.A new type of GG gel system was constructed,which realized simple and efficient rapid crosslinking of GG colloids and obtained zero-dimensional,one-dimensional and two-dimensional GG gel systems.Due to the strong affinity between the transition metal hydroxide and the GG molecule,the transition metal hydroxide can act as a cross-linking agent in the GG network structure and promote the rearrangement of the GG chain molecules in three-dimensional space and maintain stability Colloid structure.In addition,we systematically studied the gel behavior of the GG/Cu mixed colloid in an alkaline environment,and investigated the existence of transition metal hydroxide nanoparticles in the GG gel network.Based on the above results,the gel mechanism of the composite system is proposed.The construction strategy of the gel system provides a new idea for the application of GG colloid in other fields.(2)Preparation of copper-containing layered hollow HAp beads by rapid gel method.In order to construct a HAp ball material with rich pore structure,cavity structure and antibacterial properties,so as to meet the needs of bone fillers for bone defect repair,based on the rapid setting properties of GG,a hollow hierarchical structure ball HAp with antibacterial activity was designed and prepared.On the one hand,the disordered stacking of the sheet-like constituent units of the material gives it a rich pore structure,which is expected to be used as a drug carrier for bone repair;on the other hand,the generation of a cavity structure greatly increases the specific surface area of the material,and improve the drug carrying capacity of the material.At the same time,the addition of copper ions in the HAp lattice can change the degradation behavior and ion release rate of the beads,and endow the material with excellent antibacterial activity.The system has good biocompatibility and provides a new idea for the development of multifunctional bone filler systems.(3)Micro-nano hierarchical structure copper and strontium co-doped HAp fiber scaffold.The improvement of bone repair performance of calcium phosphate bone tissue engineering scaffold is closely related to the surface topology,pore connectivity and chemical composition of the material.In order to further improve the osteogenic activity of the scaffold material and endow the material with multifunctional characteristics,a copper-strontium co-doped HAp fiber scaffold system was designed and prepared.The system uses GG/calcium phosphate gel fiber as a structural unit,and forms a fiber porous scaffold through molding,drying and calcining.The winding and stacking of a single fiber in a three-dimensional space gives the scaffold a three-dimensional connected pore structure.In addition,the mutual stacking of sheet-like structural units on the fiber surface gives the scaffold a rich pore and microporous structure;the introduction of Sr and Cu in the scaffold system makes the scaffold possess good osteogenic activity and antibacterial activity.The porous fiber scaffold system shows good biocompatibility and is expected to be used in the field of bone repair.