Recombinant silk proteins provide a route toward sustainable and biocompatible materials. For making such materials, the assembly process from dilute protein into a functional material is central. The assembly mechanism in engineered materials is by necessity different from the natural ones—this poses challenges but also opens opportunities for scaling up and for developing novel properties. The phase behavior of a mini-spidroin, NT-2Rep-CT is studied, which is a widely studied variant of recombinant silk. NT-2Rep-CT can be triggered to assemble by lowering the pH, but even at high pH—considered as storage conditions—it can be in various states, such as forming condensates, clusters, gels, and soluble protein. It is shown how its assembly phases evolve through both metastable and dynamically arrested states. The observed behavior of silk protein solutions is highly complex, and elements thereof from phase diagrams associated with polymers, colloidal systems, and globular proteins are found. Based on the characterization of cluster formation and structural intermediates, a minimalist phase diagram is proposed for NT-2Rep-CT and argues that the understanding and insight into silk assembly via its phase behavior, and especially the arrested states, is central for designing recombinant silk proteins and their processing for materials applications.

中文翻译：

---

亚稳态液-液相分离和老化导致微型蛛丝解决方案具有很强的加工路径依赖性


重组丝蛋白为可持续和生物相容性材料提供了一条途径。为了制造此类材料，从稀释蛋白质组装成功能材料的过程是核心。工程材料的组装机制必然不同于天然材料——这带来了挑战，但也为扩大规模和开发新特性提供了机会。研究了迷你蛛丝蛋白 NT-2Rep-CT 的相行为，它是一种广泛研究的重组丝变体。 NT-2Rep-CT 可以通过降低 pH 值来触发组装，但即使在高 pH 值（被视为储存条件）下，它也可以处于各种状态，例如形成冷凝物、簇、凝胶和可溶性蛋白质。它显示了其组装阶段如何通过亚稳态和动态停滞状态演变。观察到的丝蛋白溶液的行为非常复杂，并且从与聚合物、胶体系统和球状蛋白相关的相图中发现了其元素。基于簇形成和结构中间体的表征，为 NT-2Rep-CT 提出了一个极简相图，并认为通过其相行为，特别是捕获状态来理解和洞察丝组装，对于设计重组丝至关重要蛋白质及其材料应用加工。