Hemostatic, antiextravasation, and prehealing drug droplet directional transportation of antibacterial Janus wound plaster based on the structural and wettability gradients

Abstract Uncontrolled bleeding and bacterial infections are major causes of wounds that do not heal. However, developing a wound plaster that can stop bleeding, resist blood extravasation, and realize directional transportation of drugs to promote wound healing remains a significant challenge. This study developed a superhydrophilic/hydrophobic PVA/CS/Ag@TPU Janus membrane with structural and wettability gradients. Water is absorbed from blood via the superhydrophilic layer attached to the wound and charge interactions between introduced chitosan (CS) and platelets promote blood clotting. The capillary pressure resistance (∆p > 0) from the superhydrophilic layer to the hydrophobic layer can prevent blood from permeating, reducing blood loss. A favorable ∆p ( < 0 ) based on structural and wettability gradients can realize the directional transportation of drugs that promote wound healing from the hydrophobic to superhydrophilic layer. The incorporation of CS and Ag endows Janus wound plaster with intrinsic antibacterial activity (99.9%). The bacterial antiadhesion capability of wound plaster can be achieved due to the resisting effect of the hydrated layer that formed on the hydrophilic layer, its low adhesion, and antibacterial capability. Experiments on mice with full-thickness skin defects showed that the wound-healing rate using the Janus membrane after dosing with a drug increased from 87.65% (without the drug) to approximately 100%. Moreover, it could accelerate wound healing, regenerate epidermal and granulation tissue, promote collagen formation, and reduce the scar area. This gradient-design strategy opens an avenue for next-generation wound dressings.