Chemical Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459, Singapore.
Phys Rev Lett. 2018 Jan 26;120(4):048003. doi: 10.1103/PhysRevLett.120.048003.
Grafting linkers with open ends of complementary single-stranded DNA makes a flexible tool to tune interactions between colloids, which facilitates the design of complex self-assembly structures. Recently, it has been proposed to coat colloids with mobile DNA linkers, which alleviates kinetic barriers without high-density grafting, and also allows the design of valency without patches. However, the self-assembly mechanism of this novel system is poorly understood. Using a combination of theory and simulation, we obtain phase diagrams for the system in both two and three dimensional spaces, and find stable floppy square and CsCl crystals when the binding strength is strong, even in the infinite binding strength limit. We demonstrate that these floppy phases are stabilized by vibrational entropy, and "floppy" modes play an important role in stabilizing the floppy phases for the infinite binding strength limit. This special entropic effect in the self-assembly of mobile DNA-coated colloids is very different from conventional molecular self-assembly, and it offers a new axis to help design novel functional materials using mobile DNA-coated colloids.
将带有互补单链 DNA 开口端的接头接枝，可形成一种灵活的工具来调节胶体之间的相互作用，从而有利于复杂自组装结构的设计。最近，人们提出用可动 DNA 接头来包覆胶体，这不仅缓解了高密度接枝带来的动力学障碍，还可以设计出非补丁型配位数。然而，该新型系统的自组装机制尚不清楚。我们通过理论和模拟的结合，获得了二维和三维空间中该系统的相图，并发现当结合强度较强时，即使在无限结合强度极限下，也会出现稳定的柔软方形和 CsCl 晶体。我们证明这些柔软相是由振动熵稳定的，并且在无限结合强度极限下，“柔软”模式在稳定柔软相方面起着重要作用。这种在可动 DNA 包覆胶体自组装中出现的特殊熵效应与传统的分子自组装有很大不同，它为使用可动 DNA 包覆胶体设计新型功能材料提供了一个新的方向。
