A Topological Stitching Strategy for Biocompatible Wet Adhesion Using Mussel-Inspired Polyurethane

The biomedical and surgical applications of hydrogels demand effective methods to adhere hydrogels to diverse substrates including living tissues. Here we present a mussel mimetic polyurethane as topological suture material for tough adhesion of hydrogels by introducing catechol moieties into polymer chains. Solution of the stitching polyurethane can be injected onto the surface of a hydrogel, followed by diffusing spontaneously into the hydrogel, then get triggered by oxidant for in situ gelation. Oxidative cross-linkage of catechol-modified polyurethane after penetration into hydrogels or living tissues could establish enough covalently entangled networks to afford desired adhesion strength. The mussel mimetic polyurethane demonstrates excellent adhesion strength of hydrogels to universal substrates including inorganics, polymers, and biomaterials, with no requirements for specific functional groups or chemical modification. The adhesion energy achieved by the topological stitching strategy can reach up to 350 J/m². Moreover, the stitching polymer shows good biocompatibility and the potential for debonding under the catalysis of elastase. This work will possibly become a promising strategy candidate for adhesion in wet environments.