Regulating wound moisture for accelerated healing: A strategy for the continuous drainage of wound exudates by mimicking plant transpiration

Abstract Exudate regulation, which helps maintain an optimal moisture content in the wound bed and protects the surrounding skin from maceration, is a prerequisite for wound healing. In this study, inspired by the natural hierarchical structure of sugarcane, in which vascular bundles are responsible for transporting water and parenchyma cells are responsible for storing sucrose, we fabricated a continuously self-draining sugarcane stem-based dressing to remove exudates from overhydrated wounds. Sugarcane cellulosic frameworks (SCF), obtained via alkali and de-sugaring treatments of natural sugarcane substrates (SS), were coated with gold nanorods (AuNRs) to facilitate photothermal responsiveness under near-infrared (NIR) irradiation. By mimicking plant transpiration and incorporating a stimulus-responsive feature, natural SS were transformed into exudate-managing dressing materials for accelerated wound healing. As the obtained sugarcane frameworks (Au@SCF) contained abundant vascular bundles and exhibited photothermal responsiveness, it was able to self-drain exudates continuously with a high evaporation efficiency (95%). In order to endow the dressing with antibacterial properties, Ag nanoparticles (AgNPs) was incorporated with Au@SCF to form Ag@Au@SCF. The healing process in a wound model was more rapid with Ag@Au@SCF with NIR irradiation than with a commercial dressing. Moreover, as the parenchyma cells in Ag@Au@SCF formed closed chambers after de-sugaring, Ag@Au@SCF facilitated effective thermal insulation (thermal conductivity of 0.04 W m-1k-1) for protecting the underlying wound, even when the temperature of the top surface was high (53 °C). As this hierarchical structure is naturally existent in other Poaceae plants, which are sustainable green resources, our findings may provide a new strategy for the fabrication of versatile and efficient self-draining dressings for exudate management and wound healing.