Erb Randall M, Son Hui S, Samanta Bappaditya, Rotello Vincent M, Yellen Benjamin B
Duke University, Department of Mechanical Engineering and Materials Science, Center for Biologically Inspired Materials and Material Systems, Box 90300, Hudson Hall, Durham, North Carolina 27708, USA.
Nature. 2009 Feb 19;457(7232):999-1002. doi: 10.1038/nature07766.
The assembly of complex structures out of simple colloidal building blocks is of practical interest for building materials with unique optical properties (for example photonic crystals and DNA biosensors) and is of fundamental importance in improving our understanding of self-assembly processes occurring on molecular to macroscopic length scales. Here we demonstrate a self-assembly principle that is capable of organizing a diverse set of colloidal particles into highly reproducible, rotationally symmetric arrangements. The structures are assembled using the magnetostatic interaction between effectively diamagnetic and paramagnetic particles within a magnetized ferrofluid. The resulting multipolar geometries resemble electrostatic charge configurations such as axial quadrupoles ('Saturn rings'), axial octupoles ('flowers'), linear quadrupoles (poles) and mixed multipole arrangements ('two tone'), which represent just a few examples of the type of structure that can be built using this technique.
用简单的胶体构建单元组装复杂结构，对于制造具有独特光学性质的建筑材料（例如光子晶体和DNA生物传感器）具有实际意义，并且对于增进我们对分子到宏观长度尺度上发生的自组装过程的理解至关重要。在此，我们展示了一种自组装原理，该原理能够将各种胶体颗粒组织成高度可重复的旋转对称排列。这些结构是利用磁化铁磁流体中有效抗磁性和顺磁性颗粒之间的静磁相互作用组装而成的。所得的多极几何形状类似于静电荷配置，如轴向四极子（“土星环”）、轴向八极子（“花朵”）、线性四极子（极）和混合多极排列（“双色”），这些只是使用该技术可以构建的结构类型的几个例子。
