Mechanically Programmed Janus Hydrogel Patch for Hydration-Triggered Gastrointestinal Sealing

Gastrointestinal leakage is difficult to control because intestinal tissue is wet, deformable, and exposed to intraluminal pressure. An effective sealant must reinforce early wound apposition while minimizing pathological adhesion to surrounding organs. Here, we present a mechanically programmed Janus hydrogel patch that functions as a one-shot, hydration-triggered actuator for sutureless gastrointestinal sealing.

The patch consists of a tissue-facing gallic acid-conjugated chitosan (CG) layer and a peritoneal-facing crosslinked hyaluronic acid (cHA) backing. CG provides gallol-mediated wet adhesion, while cHA provides a hydrated anti-adhesive and swelling-responsive network. The CG/cHA bilayer was fabricated by sequential freezing and lyophilization, followed by secondary network compaction. This step densifies the CG adhesive interface and stores recoverable elastic energy in the cHA backing.

Upon exposure to physiological fluid, the compressed cHA layer rapidly undergoes hydration-triggered self-deployment. Under confinement, this expansion is converted into active tamponade pressure, generating approximately 4–26 mmHg. This transient pressure reinforces the critical early sealing stage by pressing the adhesive interface against the defect, while the hydrated cHA surface subsequently serves as an anti-adhesive barrier. UV–Vis spectroscopy, 1H NMR, rheology, and FE-SEM confirmed gallol conjugation, cHA network formation, and compaction-induced densification. Ex vivo intestinal models showed compaction- and confinement-enhanced burst resistance. In a high-mortality sutureless cecal puncture model, optimized CG-HA achieved complete survival, reduced pathological adhesion, and supported organized mucosal restoration. These findings suggest that hydration-triggered mechanical programming can create active biointerface hydrogel patches for sutureless gastrointestinal repair.