Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States.
Materials Science and Engineering, University of California, San Diego, La Jolla, California 92093, United States.
J Am Chem Soc. 2020 Nov 11;142(45):19402-19410. doi: 10.1021/jacs.0c10065. Epub 2020 Oct 30.
The mechanical and functional properties of many crystalline materials depend on cooperative changes in lattice arrangements in response to external perturbations. However, the flexibility and adaptiveness of crystalline materials are limited. Additionally, the bottom-up, molecular-level design of crystals with desired dynamic and mechanical properties at the macroscopic level remains a considerable challenge. To address these challenges, we had previously integrated mesoporous, cubic ferritin crystals with hydrogel networks, resulting in hybrid materials (polymer-integrated crystals or PIX) which could undergo dramatic structural changes while maintaining crystalline periodicity and display efficient self-healing. The dynamics and mechanics of these ferritin-PIX were devoid of directionality, which is an important attribute of many molecular and macroscopic materials/devices. In this study, we report that such directionality can be achieved through the use of ferritin crystals with anisotropic symmetries (rhombohedral or trigonal), which enable the templated formation of patterned hydrogel networks in crystallo. The resulting PIX expand and contract anisotropically without losing crystallinity, undergo prompt bending motions in response to stimuli, and self-heal efficiently, capturing some of the essential features of sophisticated biological devices like skeletal muscles.
许多晶体材料的机械和功能特性取决于晶格排列在外部扰动下的协同变化。然而，晶体材料的灵活性和适应性是有限的。此外，在宏观尺度上设计具有所需动态和机械性能的晶体的自下而上、分子水平的设计仍然是一个相当大的挑战。为了解决这些挑战，我们之前已经将介孔立方铁蛋白晶体与水凝胶网络集成在一起，得到了具有可显著改变结构同时保持晶体周期性并显示高效自修复的杂化材料（聚合物整合晶体或 PIX）。这些铁蛋白-PIX 的动力学和力学性质没有方向性，这是许多分子和宏观材料/器件的一个重要属性。在这项研究中，我们报告说，通过使用具有各向异性对称性的铁蛋白晶体（菱形或三角）可以实现这种方向性，这使得可以在结晶中模板形成图案化水凝胶网络。所得的 PIX 可以各向异性地膨胀和收缩而不失去结晶度，能够快速响应刺激进行弯曲运动，并有效地自我修复，从而捕获了一些复杂生物设备（如骨骼肌）的基本特征。
