Bachtiar Emilio O, Erol Ozan, Millrod Michal, Tao Runhan, Gracias David H, Romer Lewis H, Kang Sung Hoon
Department of Mechanical Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218, USA; Hopkins Extreme Materials Institute, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218, USA.
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, 600 North Wolfe St, Baltimore, MD 21205, USA.
J Mech Behav Biomed Mater. 2020 Apr;104:103649. doi: 10.1016/j.jmbbm.2020.103649. Epub 2020 Jan 23.
Recent advancements in 3D printing have revolutionized biomedical engineering by enabling the manufacture of complex and functional devices in a low-cost, customizable, and small-batch fabrication manner. Soft elastomers are particularly important for biomedical applications because they can provide similar mechanical properties as tissues with improved biocompatibility. However, there are very few biocompatible elastomers with 3D printability, and little is known about the material properties of biocompatible 3D printable elastomers. Here, we report a new framework to 3D print a soft, biocompatible, and biostable polycarbonate-based urethane silicone (PCU-Sil) with minimal defects. We systematically characterize the rheological and thermal properties of the material to guide the 3D printing process and have determined a range of processing conditions. Optimal printing parameters such as printing speed, temperature, and layer height are determined via parametric studies aimed at minimizing porosity while maximizing the geometric accuracy of the 3D-printed samples as evaluated via micro-CT. We also characterize the mechanical properties of the 3D-printed structures under quasistatic and cyclic loading, degradation behavior and biocompatibility. The 3D-printed materials show a Young's modulus of 6.9 ± 0.85 MPa and a failure strain of 457 ± 37.7% while exhibiting good cell viability. Finally, compliant and free-standing structures including a patient-specific heart model and a bifurcating arterial structure are printed to demonstrate the versatility of the 3D-printed material. We anticipate that the 3D printing framework presented in this work will open up new possibilities not only for PCU-Sil, but also for other soft, biocompatible and thermoplastic polymers in various biomedical applications requiring high flexibility and strength combined with biocompatibility, such as vascular implants, heart valves, and catheters.
3D打印技术的最新进展彻底改变了生物医学工程，它能够以低成本、可定制和小批量制造的方式生产复杂且功能化的设备。软质弹性体对于生物医学应用尤为重要，因为它们能提供与组织相似的机械性能，同时具有更好的生物相容性。然而，具有3D打印能力的生物相容性弹性体非常少，人们对生物相容性3D可打印弹性体的材料特性了解甚少。在此，我们报告了一种新的框架，用于3D打印一种缺陷最少的柔软、生物相容且生物稳定的聚碳酸酯基聚氨酯硅氧烷（PCU-Sil）。我们系统地表征了该材料的流变学和热性能，以指导3D打印过程，并确定了一系列加工条件。通过参数研究确定了最佳打印参数，如打印速度、温度和层高，目的是在通过微型CT评估3D打印样品时，在使孔隙率最小化的同时最大化几何精度。我们还表征了3D打印结构在准静态和循环加载下的机械性能、降解行为和生物相容性。3D打印材料的杨氏模量为6.9±0.85MPa，断裂应变率为457±37.7%，同时表现出良好的细胞活力。最后，打印了包括患者特异性心脏模型和分叉动脉结构在内的柔性自立结构，以展示3D打印材料的多功能性。我们预计，这项工作中提出的3D打印框架不仅将为PCU-Sil开辟新的可能性，也将为其他柔软、生物相容且热塑性的聚合物在各种需要高柔韧性、强度以及生物相容性的生物医学应用中开辟新的可能性，如血管植入物、心脏瓣膜和导管。
