액정, 코아세르베이트 및 나노피브릴 기반 실크 섬유 방사 메커니즘

초록

Silk fiber spinning converts concentrated aqueous protein dopes into high-performance filaments under ambient conditions, yet its mechanistic basis remains actively debated. Historically, liquid crystalline ordering, micelle-based self-assembly, liquid-liquid phase separation (LLPS)/coacervate formation, and nanofibril-based hierarchical assembly have been proposed as competing frameworks. This review reinterprets these models as condition-dependent stages of a multistep process rather than mutually exclusive theories. We introduce a multidimensional condition-pathway map wherein specific combinations of pH, ionic environment, protein concentration, and flow conditions select distinct structural intermediates and transition pathways. Critically, LLPS-induced concentration amplification and flow-enhanced liquid crystalline alignment are demonstrated to operate as sequential and synergistic mechanisms. The framework incorporates molecular-level interactions, including cation-π contacts and kosmotropic anion effects, that govern phase boundaries and condensate stability. The applicability of each model is systematically examined across four silk systems: spider dragline silk, silkworm silk, regenerated silk fibroin, and recombinant spidroins, recognizing system-specific mechanistic variations. This integrated perspective clarifies how apparently conflicting experimental observations can be reconciled within a unified condition-dependent framework and provides design principles for biomimetic spinning and next-generation protein fiber engineering.

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