Water-Triggered Pre-activation of Hydrogel Patch for Instant Robust Bioadhesion.

Bioadhesives represent promising alternatives to sutures and staples for skin wound repair; however, existing systems are often limited by complex fabrication processes, poor adhesion under wet conditions, insufficient mechanical strength, and biocompatibility concerns. To address these challenges, we propose a prehydration-activated, dry-state adhesion strategy. Herein, an acrylic acid-methacrylic acid copolymer hydrogel patch (AM gel) is fabricated via a simple one-pot synthesis and exhibits a unique hydration-triggered activation behavior. Upon exposure to water, the carboxylic acid (-COOH) groups inherent in the AM gel ionize, releasing protons and generating a highly reactive interfacial state, thereby converting the material into a preactivated hydrogel. Upon subsequent contact with skin, the activated gel forms strong, durable adhesion to stratum corneum proteins bearing amino (-NH2) groups through complementary interfacial interactions. As a result, the AM hydrogel achieves an exceptional shear adhesive strength of 174.99 ± 6.55 kPa and maintains stable adhesion for over 30 min. In addition, the AM gel exhibits robust mechanical properties, excellent biocompatibility, and high compliance with soft tissues, highlighting its potential as a reliable, low-irritation adhesive platform for wound closure and wearable medical devices.