Tough adhesive bilayer hydrogels.

Adhesive hydrogels have the potential to address unmet clinical needs in the fields of wound closure, hemostasis, and soft-tissue reinforcement. However, commercial adhesives are limited by weak adhesion to internal organs and poor mechanical performance, especially in the fully swollen state. This study reports a bilayer hydrogel that combines an alginate-acrylamide double-network gel on one side and a highly entangled polyacrylamide gel on the other side to synergistically achieve robust mechanical and tissue-adhesive properties in the swollen state. Cohesion between both layers was achieved by controlling the diffusion of acrylamide between them during polymerization. The bilayer construct achieved stronger mechanical properties under tensile stress and higher performance in burst pressure tests than the double-network gel alone. The improved mechanical performance in the fully swollen state of bilayer hydrogels may expand the range of biomedical applications.