Preparation And Performance Of Hierarchical Bioceramics

The massive bone defect remains a challenge in clinic.The key factors of repairing the massive bone defect are improving the bioactivity and mechanical performances of bone biomaterials to match the new bone regeneration.There are some studies about enhancing the bioactivity and mechanical properties of biomaterials from the perspective of designing the composition of biomaterials,for example,utilizing the bioactive factors to accelerate the bone forming and using metal materials to enhance the mechanical strength of biomaterials.However,prepared materials using these methods exhibit lots of shortages.Thus,designing the high-performance biomaterials from the perspective of structure might be important and effective in repairing the massive bone defect.The purpose of this thesis is improving the bioactivity and mechanical performances of bioceramics using the biomimetic strategy and replicating the natural hierarchical structures.The main conclusions of this thesis are following:1.Inspired by the constitution,structure and function of hot dog,we utilized the strategy of combining DIW 3D printing with bidirectional freezing and successfully prepared the hierarchical hot dog-like scaffolds which consisted of hollow tube embedded by bioceramic rods with uniformly aligned lamellar microstructures.The prepared hot dog-like scaffolds exhibited hierarchical microstructure with improved specific surface area,which significantly enhanced the drug/protein delivery,cell proliferation and osteogenic differentiation of r BMSCs.Owing to the hierarchical lamellar microstructures and Ica delivery in scaffolds,the hot dog-like scaffolds could significantly promote the formation of new bone tissue.The hot dog-like scaffolds can be used for the multifunctional biomaterials for drug delivery,which is similar with the “hot dog” that provides the energy and nutrients for the body.Thus,we achieve the imitation of “hot dog” from the structure to the functions.This study breaks the limitation of the bone formation in the structs of scaffold and reveals a universal method for the design of hierarchical structures,which might open a new direction for the regenerative medicine,drug delivery and tissue engineering.2.Inspired by the “brick-and-mortar” microstructure of nacre,we combined the bidirectional freezing and resin infiltration and successfully fabricated lamellar silicate-based bioceramic composites with excellent mechanical properties matching to the cortical bone,breaking the limitation of stress shielding effect of high strength of implant biomaterials.Additionally,the lamellar silicate-based bioceramic composites could efficiently control the release rate of bioactive ions,which played significant roles in the proliferation of r BMSCs and PDLCs.Interestingly,accompanied by the degradation of bioceramics and release of bioactive ions,the new bone tissue could well grow into inner of lamellar silicate-based bioceramic composites and form the bioceramic/new bone/resin sandwich-like microstructures.Overall,the study indicated a future direction in designing high performance of bone implant biomaterials from the viewpoint of biomimics.3.Inspired by the growth mechanism and texture structure of natural bone,we propose a powerful and universal BAS approach for the fabrication of “real bone”-like textured meta-bioceramics.The prepared textured bioceramics exhibit the mechanical performances that totally match the cortical bone,due to the “real bone”-like texture structure and the interesting interface toughening mechanism.In addition,it is found that the texture structure is important for modulating the cell fates and accelerating the bone regeneration in vivo.Thus,we realize the “real bone” from the growth mechanism and texture structure to the mechanical performances and biological functions.This “real bone”-like biomaterials break the limitations of the current orthopedic materials and might trigger a revolution in this field.Notably,the BAS approach could be easily extended to the fabrication of other ceramic such as textured structural and functional ceramics.This work opens a new avenue for the fabrication of high-performance textured ceramics,broadens the horizons for the interface toughening mechanism of carbon-containing composites and the structure design of bone implant materials.In summary,we have fabricated hierarchical bioceramics with great bioactivity and excellent mechanical performances from the perspective of bionic.The strategy of combing the bionic and tissue engineering would be effective in toughening the bioceramics and repairing the massive bone defect.