(K,Na)NbO3-based lead-free ceramic/polyvinylidene fluoride piezoelectric composite for biomimetic wound healing via endogenous electric field simulation

KNN nanoparticles act as nucleating agents in PVDF films, promoting β-phase formation and enhancing piezoelectric properties. • The piezoelectric field generated by KNN/PVDF film promotes fibroblast migration. • Elevated TGF-β and VEGF expression accelerates angiogenesis and wound healing. Electrical stimulation that mimics endogenous electric fields represents a promising therapeutic strategy for wound healing. In this study, a lead-free piezoelectric composite film was fabricated by incorporating (K,Na)NbO 3 (KNN) ceramics into a polyvinylidene fluoride (PVDF) matrix via tape casting. The introduction of KNN fillers significantly enhanced the β-phase content and piezoelectric output of PVDF. Under ultrasound irradiation, the resulting KNN/PVDF film effectively promoted fibroblast proliferation and migration in vitro, achieving a 54.84% migration rate within 24 h and upregulating key wound-repair genes, including TGF-β and VEGF. In vivo, the composite film markedly accelerated the healing of full-thickness skin defects in rats, promoted neovascularization, and achieved approximately 95% wound closure by day 9. These results demonstrate that the KNN/PVDF composite film provides an effective wireless platform for biomimetic electrical stimulation in tissue regeneration.