Nature Communications, 7 March, 2026, DOI：https://doi.org/10.1038/s41467-026-70477-1

Cryo-ET comparison of the hierarchical ultrastructure of silkworm, spider, and artificial silk fibers

Kai Song, Haonan Zhang, Xueli Zhang, Yan Li & Ping Zhu

Abstract

Spider and silkworm silks are renowned for their exceptional mechanical properties, which arises from their ultrastructural organization. However, this architecture remains incompletely understood. Here, we apply cryo-electron tomography to examine the hierarchical organization of silkworm, spider, and artificial silks. In silkworm silk, we observe nanofibrils of ~3.6?nm in diameter, interconnected by abundant bridges and representing the smallest fibrillar features currently accessible by cryo-ET. These nanofibrils align with the fiber axis and are organized into a herringbone pattern, with stacked layers building the micron-scale filament. Spider silk displays densely packed nanofibrils with near-perfect axial alignment and minimal voids. In contrast, silkworm silk shows regionally heterogeneous gaps, whereas artificial silk lacks the ordered packing characteristic of natural materials. These observations provide a structural basis for understanding silk formation and may guide future biomimetic fiber design.

Article link：https://www.nature.com/articles/s41467-026-70477-1