Silver–Catechol Dynamic Redox Chemistry Provides Hydrogel Dressings with Sustained Antioxidant and Antibacterial Activity for Chronic Wound Care

Reactive oxygen species (ROS) overproduction and bacterial infection are prevalent challenges in diabetic wound management. Hence, hydrogel dressings with antioxidant and antibacterial (A&A) activity hold great promise for improving diabetic wound healing. However, the lack of sustained A&A activity of current hydrogel dressings necessitates frequent dressing replacements. This not only disrupts the delicate healing process but also triggers dressing-associated costs, complications, and environmental issues. Herein, a long-acting hydrogel dressing, NPs-PSH, that maintains A&A activity for over 8 days is presented. By engineering silver-deposited cuttlefish ink nanoparticles (AgCINPs) as nanoredox reactors, a silver–catechol dynamic redox chemistry is established. It combines catechol–quinone redox cycling and the catechol–Ag⁺ redox reaction synergistically, realizing the enduring regeneration of antioxidant catechol groups and the controlled release of antibacterial Ag⁺. By incorporating AgCINPs, NPs-PSH can continuously scavenge ROS and eradicate bacteria. Moreover, NPs-PSH exhibits favorable bioadhesion (14.21 kPa), biocompatibility, conductivity (0.42 S m^–1), and toughness (506.15 kJ m^–3). In a diabetic rat model, NPs-PSH demonstrates enhanced wound-healing efficacy by promoting epithelialization, reducing inflammation, and enhancing vascular regeneration, without frequent dressing changes (wear time up to 7 days). This study may provide a paradigm for the development of long-acting therapeutic strategies and undisturbed wound healing.