Research On Stereolithography 3D Printed Biomimetic Bioactive Ceramic Bone Repair Scaffold

Bone defects caused by a series of reasons such as frequent trauma and tumor resection have always been a problem that needs to be solved urgently in orthopedic clinics.Bone tissue engineering came into being a promising treatment method,giving scaffolds the function of actively inducing bone tissue regeneration and repair,thereby achieving permanent replacement of diseased tissue.However,the current bioceramic scaffolds of bone tissue engineering are often passively adapted to the biological environment after implantation.Insufficient biological activity,low mechanical strength,and the mismatch between the degradation rate and growth rate of new bone tissue are the key problems restricting the clinical application of bioceramic scaffolds.In this study,from the perspective of bionics,the bioceramic scaffolds with triplyperiodic minimal surface(TPMS-gyroid)structure were prepared by using stereolithography 3D printing technology;the effects of the bioglass-β-tricalcium phosphate(BG-TCP)composite ratio on the mechanical properties and degradation properties of materials were studied,and the biological effects related to osteogenesis in vitro and in vivo were investigated;the preparation of bioceramic scaffolds with different inter-connecting pore sizes was explored,and the influence of controllable macroscopic structure on osteogenesis in vivo was further studied.The research contents and conclusions of this paper are as follows:1.The BG-TCP composite bioceramic material system based on β-tricalcium phosphate(β-TCP)and bioglass(BG)was developed,and its application in the repair of rats’ femoral defects was studied.Firstly,ceramic slurries with appropriate rheological properties suitable for SLA 3D printing technology were prepared.The x BG-TCP(x=0,5,15,25 wt%)composite bioceramic scaffolds with TPMS-gyroid porous structure were successfully prepared.Compared with β-TCP scaffolds,BG-TCP bioceramic scaffolds have higher compressive strength and superior degradation performance.In terms of osteogenic activity in vitro,all bioceramic scaffolds have good biocompatibility and can well support the adhesion and proliferation of bone marrow mesenchymal stem cells(BMSCs)and endothelial progenitor cells(EPCs).Moreover,compared with β-TCP scaffolds,BG-TCP bioceramic scaffolds can effectively promote the osteogenic differentiation of BMSCs,the tubular formation of EPCs,and the expression of related angiogenic genes.In addition,the results of femoral defects repair in rats with scaffold implantation showed that the bone tissue successfully grow into the interior of the pore channels of x BG-TCP bioceramic scaffolds,and the bone repair effect of BG-TCP bioceramic scaffolds were better thanβ-TCP scaffolds.2.On the basis of the above studies of x BG-TCP composite bioceramic scaffolds,the components of 15BG-TCP with relatively superior biological performance were selected for subsequent studies.Further regulated the inter-connecting pores sizes of bioceramic scaffolds,and investigated its application in the repair of rabbits’ femoral defects.The TPMS-gyroid structure(Gyroid-S< Gyroid-M< Gyroid-L)bioceramic scaffolds were fabricated with different pore sizes by using SLA 3D printing technology,which were contrasted with the slip casting shaped artificial bone.The results showed that the mechanical strength of TPMS-gyroid structure bioceramic scaffolds increased with the decrease of pore size,but all of them were superior to the control ceramic scaffolds.Meanwhile the SLA 3D printed ceramic scaffolds have higher porosity and uniform distribution of pore size whichi were open pores than the slip casting shaped bioceramic scaffolds.Further in vivo studies found that the Gyroid-S bioceramic scaffolds were able to induce the formation and regeneration of more new bone in the rabbit femoral defect model.The above results indicate that controlling the structure of bioceramic scaffolds using molding process is a simple and effective way to tune the mechanical and degradation properties,and can further promote the osteogenic and vasculogenic activities of scaffold materials.In summary,this paper uses SLA 3D printing technology to endow the material with better mechanical strength,tunable degradation properties,and potential to induce osteogenesis and vascularization by adjusting components and structures.It provides an important scientific basis for the design of personalized bioceramic scaffolds and the study of novel bone regeneration repair materials,which has a huge prospect of clinical application.