Because of their similarities to biological tissues, hydrogel patches have been widely investigated as adhesives to treat wounds and injuries. The specific case of gastrointestinal tract perforation, however, is particularly complex; the hydrogel must be able to withstand acidic pH, be mechanically deformable and, ideally, be deliverable in a minimally invasive manner. Chaoqiang Fan, Malcom Xing, Shiming Yang and colleagues designed an expandable hydrogel with a mushroom-like shape that can block stomach perforation wounds and can be delivered by an endoscope. Because of its double-network design, with mixed soft and rigid components, the obtained hydrogel was both pH-resistant and elastic. Further coating of the hydrogel with silica nanoparticles improved its adhesion to the gastrointestinal wall. Loading the hydrogel with pH-regulating drugs and growth factors also promoted tissue healing. Owing to its hyperboloid shape, the hydrogel was especially effective at blocking puncture wounds and was successfully tested in isolated rabbit and minipig stomachs.