Thioesters are an essential functional group in biosynthetic pathways, which has motivated their development as reactive handles in probes and peptide assembly. Thioester exchange is typically accelerated by catalysts or elevated pH. Here, we report the use of bifunctional aromatic thioesters as dynamic covalent cross-links in hydrogels, demonstrating that at physiologic pH in aqueous conditions, transthioesterification facilitates stress relaxation on the time scale of hundreds of seconds. We show that intramolecular hydrogen bonding is responsible for accelerated exchange, evident in both molecular kinetics and macromolecular stress relaxation. Drawing from concepts in the vitrimer literature, this system exemplifies how dynamic cross-links that exchange through an associative mechanism enable tunable stress relaxation without altering stiffness.

中文翻译：

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具有缔合硫酯交联的动态水凝胶的内部催化


硫酯是生物合成途径中的重要官能团，这推动了它们作为探针和肽组装中的反应手柄的发展。硫酯交换通常通过催化剂或升高 pH 值来加速。在这里，我们报告了使用双功能芳香族硫酯作为水凝胶中的动态共价交联，证明在水性条件下的生理pH下，转硫酯化促进了数百秒时间尺度的应力松弛。我们表明，分子内氢键负责加速交换，这在分子动力学和大分子应力松弛中都很明显。该系统借鉴了 vitrimer 文献中的概念，举例说明了通过关联机制交换的动态交联如何在不改变刚度的情况下实现可调节的应力松弛。