Preparation Of Cerium-doped ?-tricalcium Phosphate Magnetic Chitosan Scaffold And Its Application In Bone Repair

As the largest living and hard tissue organ of the human body,bone bears the responsibility of vital activities.However,due to the aging of the population,various orthopedic diseases and bone trauma,are very likely to cause defects,which brings great pain and inconvenience to people's lives.Therefore,finding more and better alternatives to bone tissue has always been the focus and hotspot of research in the field of biomedical materials.Tricalcium phosphate??-TCP?has good biocompatibility and osteogenic properties due to its similarity to natural bone components.Chitosan?CS?is also widely used as a natural polysaccharide in bone repair materials.The radius of Ce³⁺is similar to that of calcium ions,but its charge is larger than that of calcium ions,and it has more affinity for intracellular calcium ion sites,so it may affect the function of bone cells and interfere with the process of bone remodeling.In my research,I adopted three-step calcination method to prepare tricalcium phosphate??-TCP?powder and tricalcium phosphate powder doped with rare earth element Cerium?Ce/?-TCP?,and prepared ferroferric oxide?Fe₃O₄?powder through hydrothermal method.Furthermore,combined?-TCP with CS,Ce/?-TCP with CS,Ce/?-TCP with CS and Fe₃O₄ through Combining and Mixing method and freeze-drying method,to prepare tricalcium phosphate/chitosan scaffolds??-TCP/CS?,Cerium-doped tricalcium phosphate/chitosan scaffold?Ce/?-TCP/CS?and Cerium-doped tricalcium phosphate/chitosan magnetic scaffold?Ce/Fe/?-TCP/CS?.To analyze the morphology,functional groups,chemical composition and image structure of the prepared materials through XRD,SEM,TEM,FTIR and other detection methods.The?-TCP powder obtained by the three-step calcination method is agglomerated in the form of irregular small particles,and the particle size is about 2⁴?m.The Ce/?-TCP powder preparedby the same three-step calcination method still exist in the form of irregular small particles as?-TCP powder,and the particle size does not change significantly,while the appearance has changed to some extent because of the change of the unit cell parameter.The?-TCP/CS scaffold,Ce/?-TCP/CS scaffold and Ce/Fe/?-TCP/CS scaffold prepared by combing and mixing method and the freeze-drying method all have three-dimensional porous structure,in addition to make the material having the properties of mechanical strength,biological activity and chemical structure similar to natural bone,the three-dimensional porous structure can also transport nutrients and waste metabolism through metabolism.Tricalcium phosphate powder and rare earth powder particles are coated or attached to chitosan to form a film surface.Human adipose-derived mesenchymal stem cells?hADSCs?and human bone marrow mesenchymal stem cells?hBMSCs?were used as models,using alkaline phosphatase staining,alizarin red staining,CCK-8 kit,immunoglobulin imprinting,fluorescent triad and Micro-CT and other methodsto perform in vivo and in vitro biological experiments of the prepared materials to verify their biocompatibility and osteoinductivity.The cell culture experiments of hADSCs and hBMSCs demonstrated that the prepared?-TCP/CS scaffold,Ce/?-TCP/CS scaffold and Ce/Fe/?-TCP/CSscaffold all have goodbiocompatibility and bone inductivity,cells can spread,stick and grow wonderfully on the occasion.When the concentration of the rare earth element Ce is controlled within a certain range?0¹0?m?,the proliferation and differentiation of the cells are promoted.However,when the concentration of rare earth element Ce²⁺reaches up to 100?m,it will inhibit the growth of cells.It was also found that the combing and mixing method which used to doping Fe₃O₄ into the scaffold material can also promote the adhesion of cells and repaired the defect of mouse skull through cell viability and Micro-CT.In summary,cerium doped tricalcium phosphate/chitosan nanohybrid porous scaffold material has important significance and broad application prospect for bone defect repair area.