Microsystems Section, Mechanical Engineering, Eindhoven University of Technology, 5612 AZ Eindhoven, the Netherlands.
Galatea Laboratory, Institute of Electrical and Microengineering, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-2002 Neuchâtel, Switzerland.
Proc Natl Acad Sci U S A. 2021 Aug 31;118(35). doi: 10.1073/pnas.2104930118.
Among the many complex bioactuators functioning at different scales, the organelle cilium represents a fundamental actuating unit in cellular biology. Producing motions at submicrometer scales, dominated by viscous forces, cilia drive a number of crucial bioprocesses in all vertebrate and many invertebrate organisms before and after their birth. Artificially mimicking motile cilia has been a long-standing challenge while inspiring the development of new materials and methods. The use of magnetic materials has been an effective approach for realizing microscopic artificial cilia; however, the physical and magnetic properties of the magnetic material constituents and fabrication processes utilized have almost exclusively only enabled the realization of highly motile artificial cilia with dimensions orders of magnitude larger than their biological counterparts. This has hindered the development and study of model systems and devices with inherent size-dependent aspects, as well as their application at submicrometer scales. In this work, we report a magnetic elastomer preparation process coupled with a tailored molding process for the successful fabrication of artificial cilia with submicrometer dimensions showing unprecedented deflection capabilities, enabling the design of artificial cilia with high motility and at sizes equal to those of their smallest biological counterparts. The reported work crosses the barrier of nanoscale motile cilia fabrication, paving the way for maximum control and manipulation of structures and processes at micro- and nanoscales.
在众多在不同尺度上发挥作用的复杂生物执行器中，细胞器纤毛代表了细胞生物学中的基本执行单元。纤毛在亚微米尺度上产生运动，主要由粘性力驱动，在脊椎动物和许多无脊椎动物的出生前后，它驱动着许多关键的生物过程。人工模拟运动纤毛一直是一个长期存在的挑战，同时也激发了新材料和方法的发展。磁性材料的使用是实现微观人工纤毛的有效方法；然而，所使用的磁性材料成分的物理和磁学性质以及制造工艺几乎仅能够实现尺寸比其生物对应物大几个数量级的高度运动的人工纤毛。这阻碍了具有固有尺寸相关方面的模型系统和器件的开发和研究，以及它们在亚微米尺度上的应用。在这项工作中，我们报告了一种磁弹性体的制备工艺，结合了定制的模塑工艺，成功地制造了具有亚微米尺寸的人工纤毛，具有前所未有的挠度能力，能够设计出具有高运动性和与最小生物对应物尺寸相等的人工纤毛。所报道的工作跨越了纳米级运动纤毛制造的障碍，为微纳尺度的结构和过程的最大控制和操纵铺平了道路。
