Hydrophilic/Hydrophobic Gradient Janus Membrane for Directional Exudate Management and Drug Diffusion-Swelling Release

Substantial wound exudate not only complicates treatment but also leads to wound infections, which significantly impede the wound-healing process. While multilayer nanofibrous dressings capable of unidirectional fluid transport represent an effective strategy for exudate management. However, enhancing the efficiency of unidirectional fluid delivery to promote the multifunctionality of dressings remains challenging. This work presents a porous multilayered fibrous dressing featuring a hydrophobic–hydrophilic gradient between the hydrophilic polyacrylonitrile/sodium polyacrylate/tetracycline hydrochloride (PAN/SPA/TCH) layers and hydrophobic polylactic acid/zinc oxide (PLA/ZnO) layers. The polyacrylonitrile/polydopamine (PAN/PDA) composite served as an adhesive interlayer to strengthen cohesion and enable the successful integration of PLA/ZnO and PAN/SPA/TCH layers through electrostatic adsorption. Meanwhile, the PDA-modified PAN layer not only provides moisture buffering and transport but also improves the wetting ability, thereby enhancing the liquid transport rate. The multilayered fibrous dressing demonstrated rapid unidirectional liquid transport with a unidirectional moisture conductivity of up to 717%. Meanwhile, the pore-size gradient of 12.4, 9.8, and 8 mm from the PLA/ZnO to PAN/SPA/TCH layer generates a capillary pressure difference which drives directional water transport, achieving a droplet permeation time of 3.69 s. Furthermore, in vitro controlled-release experiments indicated the loaded model drug TCH achieves sustained release over 96h through a synergistic combination of diffusion and polymer swelling mechanisms, exhibiting commendable antimicrobial properties. This fibrous dressing combines effective exudate management with built-in antimicrobial and antiadhesion capabilities, offering an integrated therapeutic strategy for wound healing.