Polyphenol self-polymerized three-layer Janus membranes with unidirectional fluid transport and bioactivity

Uncontrolled exudate accumulation and bacterial colonization are two major obstacles to wound healing. Here we report a three-layer Janus fibrous membrane that integrates exudate management, broad-spectrum antibacterial activity, and reactive oxygen species (ROS) scavenging within a scalable, one-step fabrication platform. The membrane was constructed by electrospinning polycaprolactone (PCL) and PCL/gelatin layers, after which a polyphenol self-polymerizing coating was deposited on the bottom PCL face by immersion in alkaline Tris buffer. Six natural polyphenols—tannic acid (TA), catechol (CC), pyrogallol (PG), gallic acid (GA), hydroxytyrosol (HT), and epigallocatechin gallate (EGCG)—were screened under identical conditions. The coating converted the bottom face from hydrophobic (∼130°) to strongly hydrophilic (20–30°), generating a wettability gradient that drives spontaneous unidirectional fluid transport from the wound interface toward the outer barrier layer. Among the six chemistries evaluated, poly-TA and poly-EGCG coatings delivered the strongest overall performance: > 90% inhibition of both S. aureus and E. coli, DPPH and ABTS radical-scavenging efficiencies of ∼70% and ∼90%, respectively, and > 85% RAW 264.7 macrophage viability under H₂O₂-induced oxidative stress at 1 mg mL⁻¹ . Performance across all endpoints correlated positively with ortho-phenolic hydroxyl count, a structure–activity relationship consistently borne out by antibacterial, cell-free antioxidant, and intracellular ROS assays. These findings demonstrate that a single polyphenol immersion step can simultaneously confer asymmetric wettability and multifunctionality on electrospinning membranes, offering a practical and chemically versatile route toward next-generation wound dressings. Structure–activity analysis links this gradient of performance to the number and ortho-positioning of phenolic hydroxyls in each monomer. The strategy is mild, substrate-tolerant, and one-step, and offers a generalizable platform for multifunctional asymmetric wound dressings. Download: Download high-res image (148KB) Download: Download full-size image A three-layer Janus electrospinning membrane with wettability gradient was fabricated via one-step in-situ polyphenol self-polymerization, realizing unidirectional exudate transport, excellent antibacterial/antioxidant/cytoprotective activities, and concentration-dependent dual functions for potential wound dressing applications.