Decoding silkworm spinning programmed by pH and metal ions

• DOI: 10.1016/j.scib.2023.12.050
• Publication Date: 2023-12-29T17:30:40Z
• Authors: Kai Song; Yejing Wang; Wenjie Dong; Zhenzhen Li; Qingyou Xia; Ping Zhu; Huawei He
• Keywords: Fibroin

Silk is one of the toughest fibrous materials known despite spun at ambient temperature and pressure with water as a solvent. It great challenge to reproduce high-performance artificial fibers comparable natural silk by bionic for incomplete understanding silkworm spinning in vivo. Here, we found that amphipol digitonin stabilized structure fibroin (NSF) large-scale screening vitro, then studied close-to-native ultrastructure hierarchical assembly NSF gland lumen. Our study showed formed reversible flexible nanofibrils mainly composed random coils sedimentation coefficient 5.8 S diameter about 4 nm, rather than micellar or rod-like assembled aggregation globular molecules. Metal ions were required nanofibril formation. The successive pH decrease from posterior (PSG) anterior (ASG) resulted gradual increase hydrophobicity, thus inducing sol-gelation transition nanofibrils. randomly dispersed PSG ASG-1, self-assembled into anisotropic herringbone patterns ASG-2 near spinneret ready spinning. findings reveal controlled self-assembly mechanism multi-scale architecture programmed metal gradient, which provides novel insights silk-secreting insects bioinspired design fibers.