Mechanically Reinforced and Injectable Universal Adhesive Based on a PEI–PAA/Alg Dual-Network Hydrogel Designed by Topological Entanglement and Catechol Chemistry

Universal adhesion of hydrogels to diverse materials is essential to their extensive applications. Unfortunately, tough adhesion of wet surfaces remains an urgent challenge so far, requiring robust cohesion strength for effective stress dissipation. In this work, a dual-network hydrogel polyethylenimine-poly(acrylic acid)/alginate (PEI-PAA/Alg) with excellent mechanical strength is realized via PEI-PAA complex and calcium alginate coordination for universal adhesion by the synergistic effort of topological entanglement and catechol chemistry. The dual networks of PEI-PAA/Alg provide mechanically reinforced cohesion strength, which is sufficient for energy dissipation during adhesion with universal materials. After the integration of mussel-inspired dopamine into PAA or Alg, the adhesive demonstrates further improved adhesion performance with a solid adherend and capability to bond cancellous bones. Notably, the dopamine-modified adhesive exhibits better instant adhesion and reversibility with wet surfaces compared with commercial fibrin. Adhesion interfaces are investigated by SEM and micro-FTIR to verify the effectiveness of strategies of topological entanglement. Furthermore, the adhesive also possesses great injectability, stability, tissue adhesion, and biocompatibility. In vivo wound healing and histological analysis indicate that the hydrogel can promote wound closure, epidermis regeneration, and tissue refunctionalization, implying its potential application for bioadhesive and wound dressing.