Tannic acid based multifunctional hydrogels with mechanical stability for wound healing.

Conventional wound dressings have poor tissue adhesion and mechanical stability, restricting their applications in dynamic motion environments. Tannic acid (TA) was ideal candidates for current dressing materials due to their well-known antioxidant and anti-inflammatory properties. However, the inevitable polymerization problem of TA limited the one-step synthesis of dressings. Herein, we reported a simple one-pot method to prepare double-network hydrogels containing N-acryloyl glycinamide (NAGA), N-hydroxyethyl acrylamide (HEAA) and TA. The resulting NHT hydrogel exhibited excellent tensile properties, fatigue resistance, and notch insensitivity to ensure mechanical stability under large deformation and stress in vitro. The NHT hydrogel also demonstrated room-temperature self-healing, broad adhesion to various substrates, synergistic swelling ability. In addition, catechol and benzene rings from TA helped shield against UV radiation and acted as free radical scavengers to relieve oxidative stress in wound damage. As a result, full-layer wounds in mice treated with NHT patches showed a higher healing rate, in which epithelialization was completed within 14 days. The integrated function enables hydrogel to maintain mechanical stability in dynamic motion environments with high strain and defects, with great potential for future clinical translation.