Research on sintering process of tricalcium phosphate bone tissue engineering scaffold based on three-dimensional printing / 生物医学工程学杂志

Tricalcium phosphate (TCP) is one of the most widely used bioceramics for constructing bone tissue engineering scaffold. The three-dimensional (3D) printed TCP scaffold has precise and controllable pore structure, while with the limitation of insufficient mechanical properties. In this study, we investigated the effect of sintering temperature on the mechanical properties of 3D-printed TCP scaffolds in detail, due to the important role of the sintering process on the mechanical properties of bioceramic scaffolds. The morphology, mass and volume shrinkage, porosity, mechanical properties and degradation property of the scaffold was studied. The results showed that the scaffold sintered at 1 150℃ had the maximum volume shrinkage, the minimum porosity and optimal mechanical strength, with the compressive strength of (6.52 ± 0.84) MPa and the compressive modulus of (100.08 ± 18.6) MPa, which could meet the requirements of human cancellous bone. In addition, the 1 150℃ sintered scaffold degraded most slowly in the acidic environment compared to the scaffolds sintered at the other temperatures, demonstrating its optimal mechanical stability over long-term implantation. The scaffold can support bone mesenchymal stem cells (BMSCs) adherence and rapid proliferation and has good biocompatibility. In summary, this paper optimizes the sintering process of 3D printed TCP scaffold and improves its mechanical properties, which lays a foundation for its application as a load-bearing bone.

Mechanical Properties Analysis and Improved Design of Scaffolds for Bone Tissue Engineering Based on Finite Element Method / 医用生物力学

Objective To analyze the mechanical properties of bone tissue engineering scaffolds with different pore structure and porosity, and improve the mechanical properties of scaffolds by changing pore structure. Methods Square pore, spherical pore and cylindrical pore with different porosities from 55% to 75% were established by SolidWorks software, and the surface-volume ratio of different structures was calculated. The stress distribution and equivalent compression modulus of different scaffolds were obtained by ANSYS Workbench software. According to the stress distribution results, the scaffold with rectangular pore structure and cuboid element structure was improved instead of square pores. Results With the increase of porosity, the surface-volume ratio of the three structures increased. For the same porosity, the surface-volume ratio of square pores and spherical pores was larger, while that of cylindrical pores was the smallest. The modulus and porosity of the three structures were approximately linear. The modulus of the square pore and the cylindrical pore were similar. The stress analysis on the square pore and two improved structures with 60% porosity showed that for the two improve structures, the wall stress on 4 edges parallel to the direction of applied stresses could be reduced by 15%. Conclusions The surface-volume ratio and mechanical property of square pores were more advantageous than spherical pores and cylindrical pores with the same porosity, and the two improved structures could improve the mechanical properties of square pores. The two improved pores enriched the structure of tissue engineering scaffolds. The research findings provide the mechanical references for their clinical application.

Polyvinyl butyral improves the properties of 3-dimensional nano-zirconia porous scaffolds for bone tissue engineering / 医学研究生学报

Objective The nano-zirconia scaffolds we previously prepared had a good 3-dimensional ( 3D ) connectivity but did not achieve the ideal sintering rate and compressive strength .The objective of this study was to explore the enhancing effect of polyvinyl butyral ( PVB) as a dispersant on the compressive strength of 3D nano-zirconia porous scaffolds for bone tissue engineering . Methods We prepared the slurry containing different concentrations of PVB and ana-lyzed the improving effect of PVB on the mechanical properties of the scaffolds by sediment experiment , compressive strength test and scan-ning electron microscopy . Results The sediment experiment showed no significant stratification in the slurry with 0.2wt%PVB, white suspension in the upper layer and white precipitate in the lower layer , with a significantly higher compressive strength of the scaffold ([0.324 ±0.030] MPa) than that of the scaffold prepared by adding other concentrations of PVB to the slurry (P <0.01).And the compressive strength of the scaffold constructed by adding no dispersant ([0.109 ±0.021] MPa) was remarkably lower than that of the scaffold constructed by adding PVB to the slurry (P<0.05).Scanning electron microscopy demonstrated that the scaffold prepared by adding 0.2wt%PVB to the slurry had a complete porous structure with the fewest and most sparsely distributed surface cracks as compared with other PVB concentration groups . Conclusion PVB can signifi-cantly improve the stability of zirconia slurry , enhance the compressive strength of the nano-zirconia porous scaffold , and make the scaf-fold more applicable to bone tissue engineering .