Tempo-Functionalized Janus Hydrogel Crosslinked by Tandem Dynamic Covalent Bonds for Internal Organ Injury Repair and Deep Second-Degree Burn Wound Healing

Wound dressings with asymmetrical adhesion performances and biological activity are urgently needed for the treatment of tissue/organ injuries. Herein, an antioxidative and Janus hydrogel (Tempo-FPF) composed of 2,2,6,6-tetramethylpiperidine-1-oxyl functionalized poly(ethylene imine) (PEI-Tempo), 2-formylphenylboronic acid (2-FPBA) and poly(vinyl alcohol) (PVA) is developed based on tandem dynamic iminoboronate and boronate ester bonds. The addition of PEI and 2-FPBA onto the top of the precursor hydrogel formed by PEI-Tempo, 2-FPBA, and PVA can endow the Tempo-FPF hydrogel with asymmetric adhesion properties owing to the differences in crosslinking density and hydrophilicity between the two sides. Moreover, profiting from Tempo functionalization, the Tempo-FPF hydrogel exhibits outstanding free radical scavenging ability. In vivo outcomes of gastric perforation and liver incision treatments in rats reveal that the Tempo-FPF hydrogel can not only enable firm injury site sealing to inhibit gastric acid leakage and bleeding but also prevent the occurrence of tissue/organ adhesion. In vivo deep second-degree burn wound study demonstrates that the Tempo-FPF hydrogel can attenuate oxidative stress-induced inflammation response within the wound site to accelerate the reconstruction of skin tissues. This work provides a promising strategy for the design of potent antioxidative hydrogel dressings with on-demand adhesion behaviors for in vivo tissue/organ injury repair.