Performance study of ZnO-TPU/CS bilayer composite electrospinning scaffold in skin wound healing.

Introduction: The high incidence of skin injuries and the limitations of conventional dressings highlight the need for advanced wound care materials. Electrospun nanofibrous scaffolds, with their extracellular matrix-like architecture, offer potential to enhance healing. Methods: A bilayer nanofibrous scaffold of thermoplastic polyurethane (TPU) and chitosan loaded with zinc oxide nanoparticles (ZnO) (TPU/CS@ZnO) was fabricated via electrospinning. The scaffold consisted of a hydrophobic TPU outer layer for waterproof protection and a hydrophilic TPU/CS@ZnO inner layer for bioactivity. Physicochemical properties were characterized by morphology, mechanical strength, and wettability. Cytocompatibility was evaluated in vitro, and wound healing efficacy was tested in vivo using a full-thickness skin defect model. Results: The scaffold displayed uniform fibres with a base-layer diameter of 231.81 ± 44.85 nm, tensile strength of 8.42 ± 0.58 MPa, and Young's modulus of 17.96 ± 0.78 MPa. Water contact angles confirmed hydrophilic and hydrophobic layer characteristics (52.68° ± 4.46° vs. 113.60° ± 2.85°). In vitro studies showed enhanced cell proliferation and adhesion, while in vivo experiments demonstrated over 90% wound closure at day 14, significantly faster than untreated groups. Histological analysis indicated contributions from cellular adhesion, angiogenesis, and immunomodulation. Discussion: The bilayer TPU/CS@ZnO scaffold integrates structural protection with biological activity, accelerating wound repair through multiple mechanisms. These findings support its potential as a multifunctional wound dressing, while further studies are needed to clarify molecular pathways and advance clinical application.