Multifunctional Three-Dimensional-Printed Bio-Ink from Waterborne Polyurethane and Natural Antioxidants for Advanced Wound Dressings

The development of multifunctional wound dressings capable of simultaneously addressing oxidative stress, bacterial infection, and tissue regeneration remains a major challenge in advanced wound care. Here, we report a printable, bioactive 3D-printed dressing based on a synergistic bio-ink composed of waterborne polyurethane (WPU), pomegranate peel-derived antioxidant polyphenols (POM), and TEMPO-oxidized cellulose nanofibrils (TOCNF). POM was incorporated into the WPU matrix during in situ polymerization to introduce pomegranate peel-derived antioxidant and antibacterial functionality, while TOCNF served as a rheology modifier enabling extrusion-based direct ink writing. The resulting ink exhibited pronounced shear-thinning behavior, rapid viscosity recovery, and tunable yield stress, enabling successful, stable extrusion-based printing of multilayer architectures. Printed freeze-dried wound dressings exhibited highly interconnected porous structures (>90% porosity), robust swelling capacity, structural integrity under physiological conditions, and compressive stability after hydration. The incorporation of POM enhanced antibacterial performance against both Staphylococcus aureus and Escherichia coli and provided strong free-radical scavenging activity. In vitro studies using HaCaT keratinocytes confirmed excellent cytocompatibility, enhanced metabolic activity, and significant attenuation of H2O2-induced oxidative stress. Notably, this wound dressing reduced intracellular reactive oxygen species levels and improved cell survival under oxidative challenge. This work establishes a strategy for integrating natural antioxidant bioactives into printable polyurethane networks to produce structurally programmable, biologically active wound dressings. The combination of rheologically optimized printability, hierarchical porosity, and multifunctional bioactivity highlights the potential of this platform for advanced wound-dressing applications and other oxidative-stress-related tissue-repair strategies.