Chemically reversible hydrogels The dynamic reorganization of some cellular biopolymers in response to signals has inspired efforts to create artificial materials with similar properties. Freeman et al. created hydrogels based on peptide amphiphiles that can bear DNA strands that assemble into superstructures and that disassemble in response to chemical triggers. The addition of DNA conjugates induced transitions from micelles to fibers and bundles of fibers. The resulting hydrogels were used as an extracellular matrix mimic for cultured cells. Switching the hydrogel between states also switched astrocytes between their reactive and naïve phenotypes. Science, this issue p. 808 Large-scale redistribution of molecules in a supramolecular material generates chemically reversible superstructures. Soft structures in nature, such as protein assemblies, can organize reversibly into functional and often hierarchical architectures through noncovalent interactions. Molecularly encoding this dynamic capability in synthetic materials has remained an elusive goal. We report on hydrogels of peptide-DNA conjugates and peptides that organize into superstructures of intertwined filaments that disassemble upon the addition of molecules or changes in charge density. Experiments and simulations demonstrate that this response requires large-scale spatial redistribution of molecules directed by strong noncovalent interactions among them. Simulations also suggest that the chemically reversible structures can only occur within a limited range of supramolecular cohesive energies. Storage moduli of the hydrogels change reversibly as superstructures form and disappear, as does the phenotype of neural cells in contact with these materials.

中文翻译：

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超结构网络的可逆自组装

化学可逆水凝胶 一些细胞生物聚合物响应信号的动态重组激发了创造具有相似特性的人造材料的努力。弗里曼等人。创造了基于肽两亲物的水凝胶，这些水凝胶可以携带 DNA 链，这些 DNA 链组装成超结构，并响应化学触发而分解。DNA 偶联物的添加诱导了从胶束到纤维和纤维束的转变。所得水凝胶用作培养细胞的细胞外基质模拟物。在状态之间切换水凝胶也会在反应性和幼稚表型之间切换星形胶质细胞。科学，这个问题 p。808 超分子材料中分子的大规模重新分布会产生化学可逆的超结构。自然界中的软结构，例如蛋白质组装，可以通过非共价相互作用可逆地组织成功能性且通常是分层的体系结构。在合成材料中对这种动态能力进行分子编码仍然是一个难以实现的目标。我们报告了肽-DNA 结合物和肽的水凝胶，它们组织成交织的细丝的超结构，这些细丝在添加分子或电荷密度变化时分解。实验和模拟表明，这种反应需要由它们之间的强非共价相互作用指导的分子的大规模空间重新分布。模拟还表明，化学可逆结构只能在有限的超分子内聚能范围内发生。随着超结构的形成和消失，水凝胶的存储模量发生可逆变化，