Department of Chemical Engineering, Stanford University, Stanford, CA, United States of America.
Department of Materials Science and Engineering, Stanford University, Stanford, CA, United States of America.
Biofabrication. 2022 May 19;14(3). doi: 10.1088/1758-5090/ac6bbe.
Three-dimensional (3D) bioprinting is a promising technique for spatially patterning cells and materials into constructs that mimic native tissues and organs. However, a trade-off exists between printability and biological function, where weak materials are typically more suited for 3D cell culture but exhibit poor shape fidelity when printed in air. Recently, a new class of assistive materials has emerged to overcome this limitation and enable fabrication of more complex, biologically relevant geometries, even when using soft materials as bioinks. These materials include support baths, which bioinks are printed into, and sacrificial inks, which are printed themselves and then later removed. Support baths are commonly yield-stress materials that provide physical confinement during the printing process to improve resolution and shape fidelity. Sacrificial inks have primarily been used to create void spaces and pattern perfusable networks, but they can also be combined directly with the bioink to change its mechanical properties for improved printability or increased porosity. Here, we outline the advantages of using such assistive materials in 3D bioprinting, define their material property requirements, and offer case study examples of how these materials are used in practice. Finally, we discuss the remaining challenges and future opportunities in the development of assistive materials that will propel the bioprinting field forward toward creating full-scale, biomimetic tissues and organs.
三维(3D)生物打印是一种有前途的技术,可将细胞和材料空间图案化到构建体中,以模拟天然组织和器官。然而,在可打印性和生物功能之间存在权衡,其中较弱的材料通常更适合 3D 细胞培养,但在空气中打印时形状保真度较差。最近,出现了一类新的辅助材料,可以克服这一限制,甚至可以使用柔软的材料作为生物墨水,来制造更复杂、更具生物学相关性的几何形状。这些材料包括支撑浴,生物墨水打印到支撑浴中,以及牺牲墨水,牺牲墨水本身被打印出来,然后再被去除。支撑浴通常是屈服应力材料,在打印过程中提供物理约束,以提高分辨率和形状保真度。牺牲墨水主要用于创建可渗透的空隙和图案网络,但它们也可以直接与生物墨水结合,改变其机械性能,以提高可打印性或增加孔隙率。在这里,我们概述了在 3D 生物打印中使用此类辅助材料的优势,定义了它们的材料性能要求,并提供了这些材料在实践中如何使用的案例研究示例。最后,我们讨论了辅助材料在开发中的剩余挑战和未来机遇,这些机遇将推动生物打印领域朝着创建全规模、仿生组织和器官的方向前进。