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In Situ Phase Transition of Elastin-Like Polypeptide Chains Regulates Thermoresponsive Properties of Elastomeric Protein-Based Hydrogels.
Biomacromolecules ( IF 6.2 ) Pub Date : 2020-03-25 , DOI: 10.1021/acs.biomac.0c00206
Tianyu Duan 1 , Hongbin Li 1
Affiliation  

Engineering protein-based hydrogels that can change their physical and mechanical properties in response to environmental stimuli have attracted considerable interest due to their promising applications in biomedical engineering. Among environmental stimuli, temperature is of particular interest. Most thermally responsive protein hydrogels are constructed from thermally responsive elastin-like polypeptides (ELPs), which exhibit a lower critical solution temperature (LCST) transition, or nonstructured elastomeric proteins fused with ELPs. Here we report the engineering of thermally responsive elastomeric protein-based hydrogels by fusing ELPs to elastomeric proteins made of tandemly arranged folded globular proteins. By fusing ELP sequence (VPGVG)n to an elastomeric protein (GR)4, which is made of small globular protein GB1 (G) and random coil sequence resilin (R), we engineered a series of protein block copolymers, Vn-(GR)4. The fusion proteins Vn-(GR)4 exhibit temperature-responsive behaviors in aqueous solution that are different from that of Vn-ELPs, as they did not exhibit the macroscopic phase transitions in the turbidity test. Instead, V48-(GR)4 and V72-(GR)4 form micelles at temperatures higher than the transition temperature of V48 and V72 at the same concentration. Using the well-developed ruthenium-mediated photochemical cross-linking method, Vn-(GR)4 polymers can be cross-linked into hydrogels, in which Vn-ELP serve as side chains of the hydrogel network. These hydrogels exhibited thermoresponsive properties due to the temperature dependent phase transition behaviors of the incorporated Vn-ELPs blocks. At elevated temperatures, the Vn-ELPs side chains in the hydrogel network underwent aggregation, leading to secondary physical cross-linking. The aggregation of the Vn-ELPs resulted in higher Young’s modulus and reduced swelling ratio. Furthermore, the amplitude of such property changes can be tuned by side chain length and composition. These results demonstrate that in situ phase behaviors of ELP side chains can regulate thermoresponsiveness of protein-based hydrogels. We anticipate that this method can be applied to other elastomeric proteins for potential biomedical applications.

中文翻译:

弹性蛋白样多肽链的原位相变调节了基于弹性蛋白的水凝胶的热响应特性。

基于工程蛋白的水凝胶可以响应环境刺激而改变其物理和机械性能,由于它们在生物医学工程中的应用前景广阔,因此引起了人们的极大兴趣。在环境刺激中,温度特别重要。大多数热响应蛋白水凝胶是由显示较低临界溶液温度(LCST)转变的热响应弹性蛋白样多肽(ELP)或与ELP融合的非结构弹性蛋白构成的。在这里,我们通过将ELP融合到由串联排列的折叠球状蛋白制成的弹性蛋白中,报告了基于热响应弹性蛋白的水凝胶的工程设计。通过将ELP序列(VPGVG)n融合到弹性蛋白(GR)4由小球状蛋白质GB1(G)和无规卷曲序列resilin(R)制成,我们设计了一系列蛋白质嵌段共聚物V n-(GR)4。融合蛋白V n-(GR)4在水溶液中表现出与V n -ELPs不同的温度响应行为,因为它们在浊度测试中没有表现出宏观的相变。相反,V48-(GR)4和V72-(GR)4在高于相同浓度下V48和V72的转变温度的温度下形成胶束。使用发达的钌介导的光化学交联方法,V n-(GR)4聚合物可以交联成水凝胶,其中V n -ELP充当水凝胶网络的侧链。由于掺入的V n -ELPs嵌段的温度依赖性相变行为,这些水凝胶表现出热响应性质。在升高的温度下,水凝胶网络中的V n -ELPs侧链发生聚集,导致二级物理交联。V n的集合-ELPs导致更高的杨氏模量和降低的溶胀率。此外,可以通过侧链的长度和组成来调节这种性质变化的幅度。这些结果表明,ELP侧链的原位相行为可以调节基于蛋白质的水凝胶的热响应性。我们预计该方法可以应用于潜在的生物医学应用的其他弹性蛋白。
更新日期:2020-03-25
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