Molecular origin for toughness of hydrogel artificial spider silk for surgical sutures

The pursuit of biomimetic fibers with simultaneous high toughness and strength persists, despite their inherent trade-offs. However, for artificial spider silk based on gel fiber, it is still unclear for the molecular chain attributes related to the improvement of the strength and toughness. Here, a hydrogel fiber was prepared by mimicking the molecular structure of natural spider silk, and we delved into the molecular chain structure characteristics related to the strength, toughness and damping capacity of gel fiber, such as crosslinking density, molecular chain orientation and hydrogen bond interaction. The results indicate that a certain increase in crosslinking density and molecular chain orientation contributes to the enhancement of tensile strength, while the toughness and damping remain essentially unaltered. The thermal dissociation of hydrogen bond could enhance the toughness in a specific range, while the humidity destruction of hydrogen bond would reduce the toughness. Through well-regulation control of the weight ratio of polyacrylamide (PAM) to poly(acrylic acid) (PAA), the PAM@PAA gel fibers could reach maximum breaking strength of 1.02 GPa, maximum toughness of 149 MJ m⁻³, and damping capacity of 95%. PAM@PAA gel fiber has demonstrated excellent wound healing performance and biocompatibility in vivo evaluation as a surgical suture, which indicates its potential in biomedical applications.