Mussel Adhesive Protein Inspired Chitin Nanowiskers Enhanced Adhesive Hydrogels for Wet Adhesion

Aiming at the challenges of low mechanical adhesion and weak wet adhesion potential faced by the traditional adhesive hydrogels, a new design strategy for adhesive hydrogel is reported in this study. Inspired by the mussel adhesive protein and the synergistic effect between cations and catechols in wet adhesion, PAHU-CS-CNF hydrogel is synthesized via one-pot method copolymerizing acrylic acid (AA), hydroxyethyl methacrylate (HEMA) and 3-trienopentadecyl-1,2-catechol (UH) with protonated chitosan (CS) and chitin nanowiskers (CNF) in aqueous solution. Since the reversible physical interactions include electrostatic attraction, hydrophobic association among alkyl chains, pi-pi stacking of benzene rings, cation-pi, hydrogen bonding and topological entanglement, the secondary networks formed by these physical bonds provide good energy dissipation for the hydrogel deformation. The synergistic effects of cations, catechols, and the water absorbability of PAHU-CS-CNF hydrogel that destructs the hydration layer on the contact interface, enable the hydrogel to form solid interfacial physical and chemical bonds interactions with wet porcine skin surface. These unique structures and mechanisms of PAHU-CS-CNF hydrogel lead to good mechanical properties (fracture strength similar to 276.4 kPa, toughness similar to 633 kJ/m(3)), excellent adhesion properties to porcine skin (interfacial toughness in wet state similar to 831 J/m(2), interfacial toughness underwater similar to 236 J/m(2), wound closure adhesion strength on skin similar to 26.2 kPa, wound closure adhesion strength on liver similar to 16.5 kPa), and the hydrogel is not easy to adhere to skin tissue in the presence of serum, given potential to prevent the wound tissue from secondary damage. The hydrogel has a great selective adhesion on biological tissue over nonbiological substrates. The PAHU-CS-CNF adhesive hydrogel may be potentially applied in the field of sutureless wound closure. [GRAPHICAL ABSTRACT]