Self-assembly of amorphous biophotonic nanostructures by phase separation
Self-assembly of amorphous biophotonic nanostructures by phase separation
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DOI：
10.1039/b902775k
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发表时间：
2009-01-01
期刊：
影响因子：
3.4
通讯作者：
Prum, Richard O.
中科院分区：
文献类型：
--
作者：
Dufresne, Eric R.;Noh, Heeso;Prum, Richard O.
动物王国中一些最鲜艳的颜色不是由色素创造的，而是由纳米结构的光的波长选择性散射创造的。在这里，我们调查准有序纳米结构的鸟类羽毛倒钩，产生生动的非虹彩颜色。这些β-角蛋白和空气纳米结构被发现在两个基本的形态：曲折的通道和无定形包装的球体。每一类纳米结构都是各向同性的，并且在组成上具有明显的特征长度变化尺度。这些局部结构相关性导致在窄的光学频率范围内的强后向散射，并且随入射角的变化很小。这种光学特性在社会和性交流中起着重要作用。为了有效，鸟类需要精确控制这些纳米结构的发展，但人们对它们如何生长知之甚少。我们假设，多个谱系的鸟类已经收敛地进化到利用相分离和动力学逮捕的自组装海绵状的颜色产生的纳米结构在羽毛倒钩。观察到的鸟类纳米结构是惊人的相似，在流体混合物的相分离过程中自组装的通道和球体的形态是相分离的特征，分别通过旋节分解和成核和生长。这些不稳定的结构被β-角蛋白基质的动力学停滞锁定，可能是通过超分子β-角蛋白纤维的缠结或交联。利用自组装的力量，鸟类可以在羽毛发育过程中以相对较小的物理和化学变化稳健地实现各种各样的纳米级形态。
Some of the most vivid colors in the animal kingdom are created not by pigments, but by wavelength-selective scattering of light from nanostructures. Here we investigate quasi-ordered nanostructures of avian feather barbs which produce vivid non-iridescent colors. These beta-keratin and air nanostructures are found in two basic morphologies: tortuous channels and amorphous packings of spheres. Each class of nanostructure is isotropic and has a pronounced characteristic length scale of variation in composition. These local structural correlations lead to strong backscattering over a narrow range of optical frequencies and little variation with angle of incidence. Such optical properties play important roles in social and sexual communication. To be effective, birds need to precisely control the development of these nanoscale structures, yet little is known about how they grow. We hypothesize that multiple lineages of birds have convergently evolved to exploit phase separation and kinetic arrest to self-assemble spongy color-producing nanostructures in feather barbs. Observed avian nanostructures are strikingly similar to those self-assembled during the phase separation of fluid mixtures; the channel and sphere morphologies are characteristic of phase separation by spinodal decomposition and nucleation and growth, respectively. These unstable structures are locked-in by the kinetic arrest of the beta-keratin matrix, likely through the entanglement or cross-linking of supermolecular beta-keratin fibers. Using the power of self-assembly, birds can robustly realize a diverse range of nanoscopic morphologies with relatively small physical and chemical changes during feather development.