Ostwald's rule of stages governs structural transitions and morphology of dipeptide supramolecular polymers
Ostwald's rule of stages governs structural transitions and morphology of dipeptide supramolecular polymers
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DOI：
10.1038/ncomms6219
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发表时间：
2014-11-01
影响因子：
16.6
通讯作者：
Gazit, Ehud
中科院分区：
文献类型：
--
作者：
Levin, Aviad;Mason, Thomas O.;Gazit, Ehud
分子结构单元自组装成纳米和微米尺度的超分子结构开辟了高分子科学的新前沿。这种超分子物种不仅具有丰富的动态功能作为其核心相互作用的非共价性质的结果，但也提供了独特的结构特征。虽然现在知道了很多关于这种结构的方式，通过它们的形态和大小分布在响应外部刺激，动力学和热力学驱动力，导致它们从可溶性单体物种转化为有序的超分子实体仍然难以捉摸。在这里，我们专注于Boc-二苯基丙氨酸，一个典型的例子，一个肽具有高倾向超分子自组织，并描述了通过它形成一系列具有不同结构特征的纳米组装的途径。我们的研究结果表明，成核过程是多步骤的性质和收益的Ostwald的步骤规则，通过可溶性单体的聚结导致形成的纳米球，然后进行熟化和结构转换，形成最终的超分子组装。我们表征的结构和热力学的不同阶段，在这个过程中，并揭示了复杂的性质的过渡，可以发生在离散的结构状态之间的这类超分子聚合物。
The self-assembly of molecular building blocks into nano-and micro-scale supramolecular architectures has opened up new frontiers in polymer science. Such supramolecular species not only possess a rich set of dynamic features as a consequence of the non-covalent nature of their core interactions, but also afford unique structural characteristics. Although much is now known about the manner in which such structures adopt their morphologies and size distributions in response to external stimuli, the kinetic and thermodynamic driving forces that lead to their transformation from soluble monomeric species into ordered supramolecular entities have remained elusive. Here we focus on Boc-diphenylalanine, an archetypical example of a peptide with a high propensity towards supramolecular self-organization, and describe the pathway through which it forms a range of nano-assemblies with different structural characteristics. Our results reveal that the nucleation process is multi-step in nature and proceeds by Ostwald's step rule through which coalescence of soluble monomers leads to the formation of nanospheres, which then undergo ripening and structural conversions to form the final supramolecular assemblies. We characterize the structures and thermodynamics of the different phases involved in this process and reveal the intricate nature of the transitions that can occur between discrete structural states of this class of supramolecular polymers.