Zero-Poisson's-ratio knitted composite dressing with PDA-Cu biomimetic coating for large-strain dynamic joint wound care

Abstract

Chronic wounds at highly mobile sites such as joints, require dressings that tolerate repeated dynamic mechanical deformations while sustaining long-term bioactivity. We developed a three-layer composite medical dressing (CMD) that integrated a Zero-Poisson's-Ratio (ZPR) mechanical framework with a polydopamine‑copper (PDACu) biomimetic coating. A ZPR weft-knitted fabric provides mechanical reinforcement, medical absorbent cotton enables exudate management, and polydopamine-mediated chelation forms an in situ Cu²⁺-loaded coating on fiber surfaces.

Mechanical testing showed that geometric rearrangement of the ZPR structure conferred anisotropic adaptability under complex strains. Quantitative hysteresis analysis further revealed load-dependent energy dissipation and buffering, particularly under constant-stress cycling. After initial cyclic rearrangement, the hysteresis loss ratio rapidly converged and stabilized, indicating robust structural stability during repeated motion. This controlled mechanical response helps preserve coating integrity and reduce stress-induced failure at mobile wound sites. Together, these behaviors address the mechanical demands of joint wounds, where repeated multidirectional movement can disrupt conventional dressings and compromise therapeutic performance. In terms of bioactivity, the PDA-Cu system enabled kinetically controlled copper-ion release. The dressing exhibited sustained broad-spectrum antibacterial activity, effective free-radical scavenging, and a procoagulant effect, together with favorable blood compatibility and a low risk of hemolysis. By coupling deformation-adaptive mechanics with sustained chemical bioactivity, this structure-function strategy supports dressing integrity during limb movement while providing antibacterial, antioxidant, and hemostatic functions. These findings establish a quantitative basis for designing durable multifunctional dressings for chronic wounds at highly mobile sites and suggest potential to promote tissue repair.