Gelation of highly entangled hydrophobic macromolecular fluid for ultrastrong underwater in situ fast tissue adhesion

Although strong underwater bioadhesion is important for many biomedical applications, designing adhesives to perform in the presence of body fluids proves to be a challenge. To address this, we propose an underwater and in situ applicable hydrophobic adhesive (UIHA) composed of polydimethylsiloxane, entangled macromolecular silicone fluid, and a reactive silane. The hydrophobic fluid displaced the boundary water, formed an in situ gel, bonded to tissues, and achieved exceptional underwater adhesion strength. Its underwater lap shear adhesion on porcine skin was significantly higher than that of cyanoacrylate and fibrin glues, demonstrating excellent water resistance. The burst pressure of UIHA on porcine skin was 10 times higher than that of fibrin glue. The cytocompatible UIHA successfully sealed ruptured arteries, skin, and lungs in rats, pigs, rabbits, and dogs. Together, the gelation of highly entangled hydrophobic macromolecular fluid provided a means to prepare underwater bioadhesives with strong bonding to tissues and excellent water resistance.