Basic Research On The Preparation Of Artificial Bone Scaffolds By 3D Printing

Background & ObjectiveWith the advancement of medical technology,more and more researchers are combining mechanical materials with 3D printing technology to investigate the feasibility of artificial bone scaffolds for bone defects.3D printing technology has various types,and fused filament fabrication(FFF)technology is widely used because of its easy operation and material diversity.In the material selection of artificial bone scaffold,as different materials have different advantages and disadvantages,a single material cannot meet the demand of preparing artificial bone scaffold,researchers have selected two or more materials to mix to make composite materials,which complements the shortcomings of a single material and amplifies its own advantages,so that the material performance can be optimized and then used as an ideal bone graft material for medical treatment.Currently,polybutylene terephthalate(PBAT)and poly(lactic acid)(PLA)composites are a hot topic of research.However,so far,there are not many reports in the literature on the preparation of PBAT/PLA artificial bone scaffolds.In this paper,polybutylene terephthalate(PBAT)and polylactic acid(PLA),a biodegradable artificial bone scaffold material,were prepared by 3D printing fused filament fabrication technology(FFF),and their properties were evaluated.Then,in vitro cellular experiments were conducted to confirm the cytocompatibility and osteogenic induction ability of the scaffold material through cell-material contact,laying the foundation for the subsequent animal experiments and clinical applications.Methods1.Firstly,the PBAT/PLA composite filament was prepared by using a multifunctional epoxy chain extender styrene-glycidyl ester(ADR)and a single-helical extruder,and the PBAT/PLA samples for tensile testing were prepared by an FFF 3D printer;the thermal stability,rheological properties and mechanical properties of the scaffolds were investigated;Three-cycle minimal surface structures(TPMS)with uniform and gradient wall thicknesses were designed separately using Rhinoceros software,and the internal structure and deformation behavior of the stents were shown by computed tomography(CT)scan.2.3D printing of PBAT/PLA artificial bone scaffold to study the cytotoxicity of mouse fibroblasts(L929)and the osteogenic properties of mouse embryonic osteoblasts(MC3T3-E1 subclone14).The experiment was divided into three groups: control group,PBAT/PLA group,and PBAT/PLA group loaded with PRP(platelet-rich plasma).The cells were co-cultured with the scaffold and placed in a cell dressing box for 96 h to obtain the extract,and the absorbance was measured by CCK-8 method at 24 h,48h and 96 h to assess the cytotoxicity of the material;the live cell staining was observed by inverted fluorescence microscopy at the same time points;The alkaline phosphatase(ALP)kit was used at d 7 and d 14 to detect the ALP content and the BCA kit to detect the amount of total protein secreted by the cells,and then the ALP activity was derived from the formula to assess the osteogenic induction capacity of the material.Results1.The material PBAT/PLA has tensile properties,thermal stability,rheological properties,compressibility,and good printability;subsequently,two periodic very small surface structures,including Schwarz P and Gyroid,were designed and 3D printed,and in particular,the uniform and gradient thickness of TPMS was achieved by Rhinoceros software,and its internal variation structure was confirmed layer by layer by CT scan,and the load-bearing capacity and energy absorption(EA)of the TPMS-G sample were superior to the TPMS-P structure,which was also confirmed in the CT scan section.2.The cell proliferation rate was found to increase with time by CCK-8 method,and the cells were stained green under inverted fluorescence microscopy,which were live cells with good cell morphology;the 3D printed PBAT/PLA scaffold promoted ALP secretion from MC3T3-E1subclone14 osteoblasts,and the ALP activity increased with time,indicating that the material has good osteogenic induction ability.Conclusion1.3D printed PBAT/PLA scaffold has good performance.2.In vitro cellular experiments confirmed that this composite scaffold structure is non-cytotoxic,promotes cell proliferation and the scaffold material has good osteogenic induction ability,which can be further investigated;cytotoxicity,proliferation assay and ALP secretion in the PRP loaded scaffold group are better than the scaffold group.