Spider silk-inspired dual-crosslinked bioadhesive for wet tissue adhesion

• A dual-crosslinked hydrogel adhesive enables robust adhesion in wet tissue environments. • Inspired by spider silk architecture, the design overcomes the mechanical weakness of catechol-based hydrogels. • The wet adhesion strength is enhanced by over 100 % compared to traditional hydrogels, reaching 60.13 kPa; wound closure rate improved by 20 %. • The structure–property relationship of the hydrogel system is systematically elucidated, with insights into the underlying microscopic mechanisms. Clinical applications urgently require hydrogel-based bioadhesives with strong wet adhesion. Catechol-based hydrogels, inspired by mussel adhesion mechanisms, have previously demonstrated excellent wet adhesive performance. However, their intrinsically amorphous polymer chains and loose three-dimensional networks result in poor overall mechanical strength, which constrains further improvement of wet adhesion. In contrast, spider silk derives its outstanding mechanical properties from a unique hierarchical structure of interlaced β-sheet nanocrystalline and amorphous domains. Drawing inspiration from spider silk, we developed a biomimetic dual-crosslinked hydrogel (pTS). In this design, the β-sheets of silk fibroin (SF) mimic crystalline domains, while covalent bonds in poly(tannic acid) (pTA) and hydrogen bonds with SF emulate amorphous regions. This architecture yields a dual-crosslinked network with hydrogen bond-mediated physical and covalent bond-driven chemical crosslinks. By introducing tannic acid (TA) self-polymerization as a tunable parameter, we elucidated how the degree of polymerization regulates the hydrogel’s mechanical and adhesive properties. Notably, the pTS hydrogel exhibited markedly enhanced wet adhesion strength—more than twice that of the conventional TS hydrogel counterparts—reaching 60.13 kPa. In vivo, pTS accelerated wound closure, significantly increasing the healing rate by nearly 20 % over the control group. This work proposes a biomimetic strategy for engineering high-performance wet bioadhesives.