Fiber-Enforced Hydrogels: Hagfish Slime Stabilized with Biopolymers including κ-Carrageenan.

Hagfish slime, a remarkable soft and elastic hydrogel, is formed by hagfish as a defense mechanism against predation. The extremely fast slime formation, the high water content, and protein threads up to 30 cm in length make it a promising material for the development of hydrogels with embedded fibers. However, under environmental conditions, i.e., in agitation in seawater, the slime collapses. To address the limited structural stability but use the potential of the protein threads as a backbone in fiber enforced materials, we generated composite structures of hagfish slime with biopolymers. Hagfish slime mixed with chitosan reveals that the slime's mucin fraction has a negative charge due to strong aggregation of both components. The gels formed by κ-carrageenan and starch show synergistic effects by exhibiting high values of water content, elasticity, and viscosity. We demonstrated that in combination with negatively charged biopolymers, fiber enforced hydrogels can be formed. This fiber enforced material has a pronounced cohesiveness and stability, thus combining both properties of biopolymers and hagfish slime.