A self-powered Zn/C micro-galvanic electrospun membrane enhances osteoimmunomodulation and accelerates cranial defect...

The repair of critical-sized cranial defects remains challenging because passive membranes provide limited biochemical and bioelectrical cues. In this study, we fabricated a spatially patterned P/C-Zn/C electrospun membrane comprising a Zn-containing central region and a carbon-containing peripheral ring. During 28 days of immersion, the membrane exhibited time-dependent Zn release, limited pH variation in the tested medium, morphological changes, and retained a measurable voltage-generating capability. Additional in vitro groups comprising P/C with exogenous Zn²⁺ and P/C subjected to external electrical stimulation were evaluated separately to examine the contributions of the two cues. The complete P/C-Zn/C membrane produced the greatest osteogenic response and the strongest shift toward an M2-associated macrophage marker profile among the tested groups. In a rat critical-sized calvarial defect model, P/C-Zn/C was associated with an increased proportion of F4/80⁺CD206⁺ cells, a pro-regenerative tissue gene-expression profile, increased bone volume and BV/TV, and improved defect bridging and collagen deposition. These findings support complementary ionic and electrical contributions to the osteogenic and immunomodulatory performance of the membrane, while direct in vivo electrical measurements and temporal immune profiling remain necessary.