Research Of Copper-containing Mesoporous Bioactive Glass/Sodium Alginate Composite Bone Tissue Engineering Scaffolds Based On Ultra-low Temperature Extruding Deposition Technology

In the field of bone repair,bone tissue engineering is currently recognized as the most potential and promising bone defect repairing trial.As a key factor determining tissue regeneration,bone tissue engineering scaffold is of significance in research.The biomechanical composition of bone is very complicated,and an ideal bone repairing scaffold is supposed to have outstanding physical,chemical and biological properties.Sodium alginate is widely used in the fabrication of bone tissue engineering scaffolds because of its excellent biocompatibility,non-immunogenicity,biodegradability and low source price.However,the defects in three-dimensional forming properties,mechanical properties and bone induction ability limit its application in the field of bone repair.In this thesis,copper-containing mesoporous bioactive glass/sodium alginate composite antimicrobial scaffolds are fabricated based on the ultra-low temperature pneumatic extruding deposition system and freeze-drying technology,with sodium alginate as the matrix material and copper-containing mesoporous bioactive glass as the functional component.Comprehensive evaluation analysis has been made on the composite scaffolds from physical,chemical and biological properties to their application prospect in the field of bone repair.The main conclusions are as follows:?1?Preparation and characterization of copper-containing mesoporous bioactive glass.The mesoporous bioactive glasses xCu-MBG?x=0,2,5 mol%?with different copper concentration are prepared through sol-gel and self-assembly process.Transmission electron microscopy and N₂ adsorption-desorption analysis show that xCu-MBG has uniform mesoporous structure.It's also found that with the increase of the molar ratio of copper ions,the microscopic morphology of bioactive glasses doesn't change significantly,while the mesoporous parameters decrease slightly.Finally,antimicrobial experiments and SBF simulated humoral immersion experiments confirm that 5Cu-MBG has good antibacterial ability and biocompatibility.?2?Fabrication and characterization of sodium alginate scaffolds.Sodium alginate scaffolds?4,5 and 6w/v%?are prepared by ultra-low temperature pneumatic extruding deposition system and freeze-drying technology,combined with cross-linking treatment by CaCl₂.These scaffolds are then observed by optical microscope and scanning electron microscope.The results show that they not only have controllable macroscopic three-dimensional structure,but also have uniform and interconnected microporous structure,with porosity are distribution between 80.4%⁸3.3%.The scaffolds have good swelling performance and the saturation mass swelling ratios are about 20²4 times.After cross-linking,the Young's modulus of sodium alginate scaffolds with different mass fraction increased from 0.32,0.42 and 0.47MPa to 0.49,0.55 and 0.63MPa,respectively.?3?Fabrication and characterization of copper-containing mesoporous bioactive glass/sodium alginate composite scaffolds.Copper-containing mesoporous bioactive glass with different concentration?0,1,1.5,and,2,w/v%?and sodium alginate?5 w/v%?composite scaffolds are prepared by ultra-low temperature pneumatic extruding deposition system and freeze-drying technology.It's observed that with the increase of the content of bioactive glass,the micropores of composite scaffolds decrease and the fiber structures become denser,with porosity decreasing from 81.8%to 76.7%.The swelling rate increases with the increase of the content of bioactive glass at first,then reduces.Still they are all higher than the swelling rate of pure sodium alginate scaffolds.The Young's modulus of these scaffolds are increased from 0.55 Mpa to 0.79,0.98 and 1.04 MPa.The mineralization ability and antibacterial properties in vitro are gradually improved.The cell experiments show that the composite scaffolds with a concentration of bioactive glass at 1 or 1.5 w/v%have improvement on the proliferation of MC3T3-E1 cells,but excessive bioactive glass?2w/v%?will lead to the alkalinity of the culture medium and the inhibition of biological activity.With comprehensive consideration,SA-CuMBG1.5 scaffold not only has good swelling rate,mechanical properties,in vitro mineralization ability and antibacterial properties,but also has a strong ability to promote cell proliferation,which could be a potential candidate for bone tissue engineering scaffold.