中央二硫键连接驱动弹性蛋白样多肽中的瞬态网络形成，实现低浓度水凝胶
A Central Disulfide Junction Drives Transient Network Formation in Elastin-Like Polypeptides, Enabling Low-Concentration Hydrogels
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中文总结 AI 辅助
本研究探究两种结构相近的可缔合三嵌段共聚物的自组装，发现中央二硫键连接可促使C16-(40)2-C16在低至2.5 wt%浓度下形成透明瞬态网络水凝胶，为低浓度水凝胶制备提供新思路。
中文摘要 AI 辅助
在水溶液中研究了由中央亲水弹性蛋白样多肽（ELP）嵌段和短脂肪酸端基（C16）组成的可缔合三嵌段共聚物的自组装行为。其中一个体系中，ELP包含80个五肽单元（C16-80-C16）；另外两个体系中，C16-ELP40链通过其末端半胱氨酸残基氧化偶联形成中央二硫键，得到C16-(40)2-C16。尽管这两种聚合物的分子量和组成几乎相同，但它们表现出显著不同的自组装行为：C16-80-C16形成大的疏水聚集体，处于动力学捕获状态，无法形成动态连接的网络；相比之下，C16-(40)2-C16形成非常小的缔合节点，聚集数仅约3条链，这些节点与更大的簇共存，并在更高浓度下动态相互连接，在低至2.5 wt%的浓度下形成透明水凝胶。振荡流变学显示，该体系存在瞬态麦克斯韦网络，由C16端基的可逆缔合相关的单一弛豫过程控制。小角X射线散射（SAXS）、光散射、冷冻透射电镜（cryo-TEM）和分子模拟均支持中央二硫键连接促进瞬态网络形成的模型。
英文摘要
The self-assembly of associative triblock copolymers composed of a central hydrophilic elastin-like polypeptide (ELP) block and short fatty acid end groups (C16) was investigated in aqueous solution. In one system, the ELP contains 80 pentapeptide units (C16-80-C16), whereas in the other two C16-ELP40 chains were oxidatively coupled through their terminal cysteine residues to form a central disulfide bond, yielding C16-(40)2-C16. Despite their nearly identical molecular weights and compositions, the two polymers exhibit markedly different self-assembly behaviors. C16-80-C16 forms large hydrophobic aggregates that remain kinetically trapped and do not develop a dynamically connected network. In contrast, C16-(40)2-C16 forms very small associative nodes with an aggregation number of only $\sim$3 chains. These nodes coexist with larger clusters and become dynamically interconnected at higher concentrations, leading to transparent hydrogels at concentrations as low as 2.5 wt %. Oscillatory rheology reveals a transient Maxwell network governed by a single relaxation process associated with the reversible association of the C16 end groups. SAXS, light scattering, cryo-TEM, and molecular modeling consistently support a model in which the central disulfide junction promotes transient network formation.
