Sprayable, antimicrobial and immunoregulation hydrogel loading exosomes based on oxidized sodium alginate for efficient wound healing at skin graft donor sites and health detection.

Skin grafting techniques are widely used for large burns, trauma, and various acute and chronic wounds, contributing greatly to the repair of traumatic tissue. However, donor site repair and regeneration are often neglected, resulting in infection and delayed healing. Therefore, it is crucial to reduce the rate of donor site infection and improve the speed and quality of healing. The low-oxidized sodium alginate (OSA) grafting ε-polylysine (OSA-g-EPL) prepared through the Schiff base reaction was used to load with mesenchymal stem cell exosomes (Exo), and crosslinked by Ca to form a gel film (HAE) on the surface of the wound by spraying. EPL provided the hydrogel with good antimicrobial properties, and Exo promoted the polarization of the M2 macrophage, shortened the inflammatory phase of the wound and rapidly transitioned to the proliferation phase, thus accelerating the wound healing process and avoiding the transition to chronic wounds. The excellent electrical conductivity and sensing properties of the hydrogel could be used to monitor the behavioral activities of mice in real time to determine their wound recovery. Therefore, this strategy will provide a promising prospect for efficient and high-quality treatment of donor site wounds.