Performance Study Of 3D Printed PLA-nHA-nMgO Composite Porous Scaffold

Objective:To construct polylactic acid(PLA)composite porous scaffolds doped with nano-magnesium oxide(n Mg O)and nano-hydroxyapatite(n HA)using 3D printing technology,and to investigate the mechanical properties,degradation characteristics,hydrophilicity,biocompatibility and osteogenic activity of the new composite scaffolds,aiming to provide personalized and new bone replacement materials for the repair and reconstruction of various types of jaw bone defects.Methods:The first part of the experiment was the preparation of composite porous scaffolds,in which PLA,n HA and n Mg O were mixed according to a pre-set ratio,and then the mixed raw materials for the composite scaffolds were prepared by dispersion,shaking and grinding.The raw materials were added to the 3D printer with pre-set parameters and modeling diagrams,and the personalized composite porous scaffolds doped with n HA and n Mg O were prepared using the fusion deposition method.The second part of the experiment is the performance study of the composite porous scaffolds.The microstructural characteristics of the scaffolds were observed by scanning electron microscopy(SEM),and the hydrophilicity of the composite scaffolds was detected by water contact angle measurement.The compressive properties of each group of scaffolds were examined by a universal mechanical testing machine,and the stress-strain curves of the materials were plotted and analyzed.The scaffolds were immersed in phosphate buffered solution(PBS)and simulated body fluid(SBF)for several days,and the weight loss of the scaffolds over time and the change of p H of the simulated body fluid were observed,respectively.Mouse embryonic osteoblast precursor cells(MC3T3-e1)were cultured in vitro and co-cultured with this cell using the immersion solution of the composite scaffold,after which the biocompatibility of the material was verified using the CCK-8 method and immunofluorescence staining.Finally,the cell culture medium was replaced with osteogenic induction medium,and the osteogenic activity of the composite scaffold was verified by alkaline phosphatase(ALP)staining assay and alizarin red staining assay.Results:The surface of the PLA-n HA-n Mg O composite porous scaffold printed according to the pre-set parameters showed a dense arrangement of micropores,which were square with a side length of 500μm and a spacing of 250μm.The molding effect of the stent doped with both n HA and n Mg O was better than that of the stent mixed with n HA alone,and the EDS detected that the two nanoparticles were uniformly doped into the stent,and the hydrophilicity of the composite stent was significantly improved.By analyzing the stress-strain curves of the scaffolds,it can be concluded that the compressive strength of the scaffolds doped with both n HA and n Mg O nanoparticles was improved,and the composite scaffold with 3%mass fraction of n Mg O had the best compressive strength.The composite scaffolds doped with n Mg O exhibited an inhibition of early degradation and an acceleration of late degradation in the degradation experiments,while the scaffolds doped with n HA alone degraded more slowly than PLA scaffolds.CCK-8 experiments and cell fluorescence staining experiments confirmed that the composite scaffolds doped with n Mg O had both good biocompatibility and cell growth-promoting effects.The osteogenic activity of the composite scaffolds showed that n HA and n Mg O had a bidirectional effect on promoting MC3T3-e1 osteogenic activity,and the promotion effect was most significant when the mass fraction of n Mg O in the composite scaffolds was 3%.Conclusion:1.The composite porous scaffold of PLA-n HA-n Mg O prepared based on3D printing technology showed significant improvements in plasticity,mechanical properties,cytological activity and osteogenic activity compared with the conventional scaffold compared with the PLA scaffold alone.2.The OH~-generated by the hydration of n Mg O in the composite scaffold effectively neutralized the acidic products of PLA scaffold during degradation in the human body,which can provide a more favorable p H environment for cell growth by providing a more favorable p H environment.