AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos Platz, Switzerland; Department of Biomaterials Science and Technology, Faculty of Science and Technology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, the Netherlands.
AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos Platz, Switzerland.
Acta Biomater. 2021 Apr 15;125:322-332. doi: 10.1016/j.actbio.2021.02.022. Epub 2021 Feb 22.
Micro-extrusion-based 3D printing of complex geometrical and porous calcium phosphate (CaP) can improve treatment of bone defects through the production of personalized bone substitutes. However, achieving printing and post-printing shape stabilities for the efficient fabrication and application of rapid hardening protocol are still challenging. In this work, the coaxial printing of a self-setting CaP cement with water and ethanol mixtures aiming to increase the ink yield stress upon extrusion and the stability of fabricated structures was explored. Printing height of overhang structure was doubled when aqueous solvents were used and a 2 log increase of the stiffness was achieved post-printing. A standard and fast steam sterilization protocol applied as hardening step on the coaxial printed CaP cement (CPC) ink resulted in constructs with 4 to 5 times higher compressive moduli in comparison to extrusion process in the absence of solvent. This improved mechanical performance is likely due to rapid CPC setting, preventing cracks formation during hardening process. Thus, coaxial micro-extrusion-based 3D printing of a CPC ink with aqueous solvent enhances printability and allows the use of the widespread steam sterilization cycle as a standalone post-processing technique for production of 3D printed personalized CaP bone substitutes. STATEMENT OF SIGNIFICANCE: Coaxial micro-extrusion-based 3D printing of a self-setting CaP cement with water:ethanol mixtures increased the ink yield stress upon extrusion and the stability of fabricated structures. Printing height of overhang structure was doubled when aqueous solvents were used, and a 2 orders of magnitude log increase of the stiffness was achieved post-printing. A fast hardening step consisting of a standard steam sterilization was applied. Four to 5 times higher compressive moduli was obtained for hardened coaxially printed constructs. This improved mechanical performance is likely due to rapid CPC setting in the coaxial printing, preventing cracks formation during hardening process.
基于微挤压的 3D 打印复杂几何形状和多孔磷酸钙（CaP）可以通过制造个性化的骨替代物来改善骨缺损的治疗效果。然而，实现打印和后打印形状稳定性对于高效制造和应用快速硬化方案仍然具有挑战性。在这项工作中，探索了同轴打印自凝固 CaP 水泥与水和乙醇混合物的方法，旨在增加挤出时的油墨屈服应力和制造结构的稳定性。当使用水基溶剂时，悬垂结构的打印高度增加了一倍，并且在打印后获得了 2 个数量级的刚度增加。标准和快速蒸汽灭菌方案作为硬化步骤应用于同轴打印的 CaP 水泥（CPC）油墨上，与没有溶剂的挤出过程相比，构建物的抗压模量提高了 4 到 5 倍。这种机械性能的提高可能是由于 CPC 快速凝固，防止了硬化过程中裂纹的形成。因此，同轴微挤压 3D 打印含有水基溶剂的 CPC 油墨可提高可打印性，并允许将广泛使用的蒸汽灭菌周期用作单独的后处理技术，以生产 3D 打印个性化 CaP 骨替代物。
用去离子水：乙醇混合物的同轴微挤压 3D 打印自凝固 CaP 水泥增加了挤出时的油墨屈服应力和制造结构的稳定性。当使用水基溶剂时，悬垂结构的打印高度增加了一倍，并且在打印后获得了 2 个数量级的刚度增加。采用标准的快速蒸汽灭菌作为硬化步骤。对于硬化的同轴打印结构，获得了 4 到 5 倍更高的抗压模量。这种机械性能的提高可能是由于同轴打印中 CPC 的快速凝固，防止了硬化过程中裂纹的形成。
