Strong, Chemically Stable, and Enzymatically on-Demand Detachable Hydrogel Adhesion Using Protein Crosslink.

Achieving strong adhesion between hydrogels and diverse materials is greatly significant for emerging technologies yet remains challenging. Existing methods using non-covalent bonds have limited pH and ion stability, while those using covalent bonds typically lack on-demand detachment capability, limiting their applications. In this study, we demonstrate a general strategy of covalent bond-based and detachable adhesion by incorporating amine-rich proteins in various hydrogels and inducing the interfacial crosslinking of the hydrogels using a protein-crosslinking agent. The protein crosslink offers topological adhesion and can reach strong adhesion energy of ≈750 J m -2 . We characterize the chemistry of the adhesion and show that the inclusion of proteins inside the hydrogels does not alter the hydrogels' properties. The adhesion remained intact after treating the adhered hydrogels with various pH solutions and ions, even at an elevated temperature. The detachment is triggered by treating proteinase solution at the bonding front, causing the digestion of proteins, thus breaking up the interfacial crosslink network. In addition, we show that this approach can be used to adhere hydrogels to diverse dry surfaces, including glass, elastomers, and plastics. The stable chemistry of protein crosslinks opens the door for various applications in a wide range of chemical environments. This article is protected by copyright. All rights reserved.