Enzyme-free oxygen-supplying containers for wound healing with immunomodulation

Immune modulation is essential for wound healing because the transition from inflammation to regeneration regulates macrophage activity, angiogenesis, and extracellular matrix remodeling. Oxygen is a key regulator of this process by promoting reactive oxygen species-mediated signaling and supporting early monocyte/macrophage recruitment. Oxygen also promotes M2 macrophage polarization, creating an anti-inflammatory microenvironment for regeneration. Although oxygen-delivering biomaterials have been developed, their application is limited by cytotoxicity caused by oxygen-generating agents and their byproducts. Here, we developed an oxygen-supplying container by immobilizing catalase on its surface via a calcium peroxide-mediated polydopamine coating. Upon the addition of hydrogen peroxide, immobilized catalase decomposed hydrogen peroxide to generate oxygen-enriched media. Preformed gelatin hydrogels composed of thiolated and maleimide-conjugated gelatin were immersed in oxygen-enriched media to fabricate agent-free, oxygen-delivering hydrogels. This strategy enabled transient hyperoxic oxygen delivery without incorporating oxygen-generating agents into the hydrogel matrix. The oxygen-delivering hydrogels accelerated wound closure, and a transient oxygen supply of 26.2% pO₂ for at least 30 min was sufficient to enhance wound healing. Mechanistically, oxygen delivery reduced F4/80-positive macrophage accumulation from 13.4% to 7.9% while increasing CD206-positive M2 macrophages from 48.4 to 68.3 cells per field, indicating a rapid transition toward a regenerative immune state. Furthermore, oxygen delivery promoted proliferation, fibroblast differentiation, and collagen I maturation, while RNA sequencing showed enhanced ECM-related gene expression. These results suggest that our oxygen-supplying container holds promise as an enzyme-free platform for oxygen delivery to promote wound healing, along with immunomodulatory effects.