Multifunctional bilayer radiative cooling dressing for regenerative wound healing under heat stress

Wound healing is influenced by local temperature. Sunlight-induced heating elevates wound temperature, which in turn exacerbates inflammation and infection risks, ultimately delaying regeneration. Despite this critical challenge, current dressings lack any capability for thermal protection. We present a bilayer radiative cooling dressing designed for passive cooling, antibacterial, and antioxidative protection. The top radiative cooling layer is a polyvinyl alcohol matrix with silicon dioxide nanoparticles and eugenol, while the bottom layer contains C-phycocyanin, a natural antioxidant and antibacterial agent. This dressing achieved a solar reflectance of 0.92 (0.3-2.5 μm) and thermal emissivity of 0.92 (8-13 μm), allowing effective heat dissipation. Under outdoor conditions, it maintained surface temperatures up to 15.2 °C below ambient. In a murine full-thickness wound model exposed to simulated sunlight, the dressing suppressed excessive heating (<40 °C) and enhanced repair, achieving 90 ± 2% wound contraction, nearly twice that of a commercial adhesive bandage (47.97 ± 3.45%). These findings integrate passive radiative cooling with antioxidative and antibacterial agent delivery, offering thermal protection and accelerated regenerative healing under heat stress conditions.