Guanidinium-Functionalized Double-Sided Tape as a Robust Tissue Adhesive Combining Bulk Water Clearance and Interfacial Dehydration

Water presents a fundamental challenge for tissue adhesives, requiring both the removal of bulk water and the interfacial hydration layer to achieve robust adhesion. Most marine-organism-inspired phenolic adhesives fail to meet key requirements for clinical use, including rapid, strong adhesion under physiological conditions, long-term stability, and scalable fabrication. Herein, we report a scalable guanidinium-functionalized double-sided tape (Gd⁺-DST) incorporating tannic acid that acts as a cross-linker and a phenolic adhesive component. This DST adheres within 5 s and achieves a record-high wet adhesion on porcine skin with interfacial toughness up to 1200 J m^-2 and shear strength up to 210 kPa after being underwater for 24 h. This performance arises from a synergistic mechanism: the Gd⁺-DST matrix rapidly absorbs and removes bulk water while suppressing swelling via chain rearrangement, and guanidinium-mediated multifaceted interactions and chaotropic properties promote interfacial dehydration and hydrophobic reorganization. These processes enable spontaneous, time-dependent adhesion reinforcement without external stimuli. Our Gd⁺-DST is flexible and biocompatible and gradually disintegrates under physiological conditions while also serving as a platform for drug loading and delivery. This study establishes a practical, multifunctional underwater adhesive with clinical relevance and offers molecular-level insights into water removal adhesion mechanisms.