In this work, we elucidated the structural organization of stimuli-responsive peptide-polydiacetylene (PDA) conjugates that can self-assemble as 1D nanostructures under neutral aqueous conditions. The amino acid sequences bear positively or negatively charged domains at the periphery of the peptide segments to promote solubility in water while also driving assembly of the individual and combined components into β-sheets. The photopolymerization of PDA, as well as the sensitivity of the resulting optical properties of the polymeric material to external stimuli, highly depends on the structural organization of the assembly of amphiphilic peptide-diacetylene units into 1D-nanostructures. Solid-state NMR measurements on C-labeled and N-labeled samples show that positively charged and negatively charged peptide amphiphiles are each capable of self-assembly, but self-assembly favors antiparallel β-sheet structure. When positively and negatively charged peptide amphiphiles interact in stoichiometric solutions, cooperative coassembly dominates over self-assembly, resulting in the desired parallel β-sheet structure with a concomitant increase in structural order. These results reveal that rational placement of oppositely charged residues can control β-strand organization in a peptide amphiphile coassembly, which would have implications on the adaptive properties of stimuli-responsive biomaterials such as the peptide-PDAs studied here.

中文翻译：

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协同β-片层共组装控制两亲肽-聚二乙炔缀合物的分子间取向


在这项工作中，我们阐明了刺激响应肽-聚二乙炔（PDA）缀合物的结构组织，该缀合物可以在中性水条件下自组装为一维纳米结构。氨基酸序列在肽片段的外围带有带正电或负电的结构域，以促进在水中的溶解度，同时还驱动单个和组合成分组装成β-折叠。 PDA 的光聚合，以及由此产生的聚合材料光学特性对外部刺激的敏感性，很大程度上取决于两亲肽-丁二炔单元组装成一维纳米结构的结构组织。 C 标记和 N 标记样品的固态 NMR 测量表明，带正电荷和带负电荷的肽两亲物均能够自组装，但自组装有利于反平行 β 片层结构。当带正电和负电的肽两亲物在化学计量溶液中相互作用时，协同共组装比自组装占主导地位，从而产生所需的平行 β-折叠结构，并伴随结构顺序的增加。这些结果表明，带相反电荷的残基的合理放置可以控制肽两亲物共组装体中的 β 链组织，这将对刺激响应生物材料（例如本文研究的肽-PDA）的适应性产生影响。