Shape-Memory Effect by Sequential Coupling of Functions over Different Length Scales in an Architectured Hydrogel.,Biomacromolecules

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Shape-Memory Effect by Sequential Coupling of Functions over Different Length Scales in an Architectured Hydrogel.
Biomacromolecules ( IF 5.5 ) Pub Date : 2019-12-17 , DOI: 10.1021/acs.biomac.9b01390
Zewang You _{1,

2,

3} , Marc Behl _{1,

3} , Stephan L Grage ₄ , Jochen Bürck ₄ , Qian Zhao ₅ , Anne S Ulrich _{4,

6} , Andreas Lendlein _{1,

2,

3}

Affiliation

The integration of functions in materials in order to gain macroscopic effects in response to environmental changes is an ongoing challenge in material science. Here, functions on different hierarchical levels are sequentially linked to translate a pH-triggered conformational transition from the molecular to the macroscopic level to induce directed movements in hydrogels. When the pH is increased, lysine-rich peptide molecules change their conformation into a β-hairpin structure because of the reduced electrostatic repulsion among the deprotonated amino groups. Coupled to this conformation change is the capability of the β-hairpin motifs to subsequently assemble into aggregates acting as reversible cross-links, which are used as controlling units to fix a temporary macroscopic shape. A structural function implemented into the hydrogel by a microporous architecture-enabled nondisruptive deformation upon compression by buckling of pore walls and their elastic recovery. Coupled to this structural function is the capability of the porous material to enhance the diffusion of ions into the hydrogel and to keep the dimension of the macroscopic systems almost constant when the additional cross-links are formed or cleaved as it limits the dimensional change of the pore walls. Covalent cross-linking of the hydrogel into a polymer network acted as gear shift to ensure translation of the function on the molecular level to the macroscopic dimension. In this way, the information of a directed shape-shift can be programmed into the material by mechanical deformation and pH-dependent formation of temporary net points. The information could be read out by lowering the pH. The peptides reverted back into their original random coil conformation and the porous polymer network could recover from the previously applied elastic deformation. The level of multifunctionality of the hydrogels can be increased by implementation of additional orthogonal functions such as antimicrobicity by proper selection of multifunctional peptides, which could enable sophisticated biomedical devices.

中文翻译：

在建筑水凝胶中，通过不同长度尺度上的函数的顺序耦合进行形状记忆效应。

在材料中集成功能以响应环境变化获得宏观效果是材料科学领域的一个持续挑战。在这里，不同层次上的功能被顺序地链接起来，以将pH触发的构象转变从分子水平转变为宏观水平，从而诱导水凝胶中的定向运动。当pH增加时，由于去质子化的氨基之间的静电排斥力降低，富含赖氨酸的肽分子将其构象改变为β-发夹结构。与此构象变化相关的是，β-发夹基序随后组装成可逆交联的聚集体的能力，该聚集体用作控制单元以固定临时的宏观形状。通过微孔结构在水凝胶中实现的结构功能使微孔壁屈曲压缩并产生弹性回复后，可实现无破坏性变形。与此结构功能相关的是，当形成或裂解其他交联键时，多孔材料增强离子向水凝胶中的扩散并保持宏观系统的尺寸几乎恒定的能力，因为它限制了聚合物的尺寸变化。孔壁。水凝胶进入聚合物网络的共价交联起变速作用，以确保将分子水平上的功能转化为宏观尺寸。通过这种方式，可以通过机械变形和临时网点的pH依赖形成，将定向变形的信息编程到材料中。可以通过降低pH值来读取信息。肽恢复到其原始的无规卷曲构象，并且多孔聚合物网络可以从先前施加的弹性变形中恢复。水凝胶的多功能的水平可以例如通过多官能肽，其可以使复杂的生物医学装置的适当选择antimicrobicity被增加执行附加的正交函数。

更新日期：2020-01-14

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