Superhydrophobic and superhydrophilic polyurethane sponge for wound healing

• Facile and robust single-sided superhydrophobic surface-modification on superhydrophilic PU sponge. • Superhydrophilic inner layer keeps the breathability, moisture retention and softness. • Superhydrophobic outer layer enables highly robust resistance to abrasion, UV irradiation and acid/alkaline. • Superhydrophobic coating can well resist bacterial invasion, biofouling, and enhance the strength and flexibility. • aSS-PU dressing shows enhanced wound healing capacity, and almost a white appearance. In this work, we successfully constructed an asymmetric superhydrophobic/superhydrophilic polyurethane sponge (aSS-PU) for wound healing. Briefly, the fluorinated zinc oxide nanoparticles (F-ZnO NPs) were anchored on one surface of polydopamine(PDA)-pre-modified superhydrophilic polyurethane sponge (S-PU) via polydimethylsiloxane (PDMS) binder by a simple one-step spraying method. The obtained light-colored aSS-PU well combined the functions of preventing bacterial invasion and anti-fouling of superhydrophobic top surface and the functions of moisture management and biocompatibility of the bottom S-PU, and simultaneously kept the excellent breathability and comfort of the high porosity and low-density structure. Additionally, the PDA/F-ZnO/PDMS functionalized superhydrophobic coating on aSS-PU not only had excellent chemical and mechanical stability, well stand sandpaper abrasion, UV irradiation and strong acids/alkaline, but also greatly enhanced the mechanical strength and flexibility of the PU sponges. The aSS-PU exhibited superior bacterial barrier properties, which could prevent bacterial invasion for at least 7 days compared with<1 day of commercially available medical gauzes and polyurethane sponge wound dressings. In a mouse full skin infected wound model, the aSS-PU also showed excellent promotion in wound healing. Therefore, the aSS-PU provides a potential novel sponge dressing for wound healing.