An All-in-One Tannic Acid-Containing Hydrogel Adhesive with High Toughness, Notch Insensitivity, Self-Healability, Tailorable Topography, and Strong, Instant, and On-Demand Underwater Adhesion

Hydrogels that are mechanically tough and capable of strong underwater adhesion can lead to a paradigm shift in the design of adhesives for a variety of biomedical applications. We hereby innovatively develop a facile but efficient strategy to prepare hydrogel adhesives with strong and instant underwater adhesion, on-demand detachment, high toughness, notch-insensitivity, self-healability, low swelling index, and tailorable surface topography. Specifically, a polymerization lyophilization conjugation fabrication method was proposed to introduce tannic acid (TA) into the covalent network consisting of polyethylene glycol diacrylate (PEGDA) of substantially high molecular weight. The presence of TA facilitated wet adhesion to various substrates by forming collectively strong noncovalent bonds and offering hydrophobicity to allow water repellence and also provided a reversible cross-link within the binary network to improve the mechanical performance of the gels. The long-chain PEGDA enhanced the efficacy and stability of TA conjugation and contributed to gel mechanics and adhesion by allowing chain diffusion and entanglement formation. Moreover, PEGDA/TA hydrogels were demonstrated to be biocompatible and capable of accelerating wound healing in a skin wound animal model as compared to commercial tissue adhesives and can be applied for the treatment of both epidermal and intracorporeal wounds. Our study provides new, critical insight into the design principle of all-in-one hydrogels with outstanding mechanical and adhesive properties and can potentially enhance the efficacy of hydrogel adhesives for wound healing.

Automated summary

This study innovatively developed a strategy to prepare hydrogel adhesives with strong underwater adhesion and high toughness, demonstrating potential biomedical applications in accelerating wound healing. The incorporation of tannic acid into a covalent network significantly enhanced the adhesion properties of the hydrogels and provided reversible cross-linking for improved mechanical performance, showing promising prospects for enhancing the efficacy of hydrogel adhesives for wound healing.