Curvature-degradation coupling drives cellular functions and osteointegration in additively manufactured biodegradable Zn-Mg scaffolds.

Abstract

Geometric curvature is a fundamental regulator of cellular functions and bone tissue regeneration, yet its interplay with degradation in biodegradable metals remains elusive due to the insufficient curvature range of existing scaffold design. Here, we introduce additively manufactured Zn-Mg scaffolds inspired by Calabi-Yau manifolds and triply periodic minimal surface, enabling a broad curvature distribution while maintaining consistent pore size and porosity. In vitro, convex regions facilitated Zn ion diffusion and Ca/P mineral deposition, whereas concave regions accumulated Zn ion and suppressed mineral formation. This spatially heterogeneous ion microenvironment reshapes cellular behaviors compared to inert Ti controls. On Ti scaffolds, osteoblasts preferentially migrate toward negatively curved regions due to curvature-driven ECM deformation and focal adhesion signaling. In contrast, on Zn scaffolds, moderate Zn²⁺ release at convex regions promotes proliferation and mineralization, mediating the intrinsic negative-curvature preference. In vivo, Zn-Mg scaffolds promoted bone regeneration and demonstrated uniform osteointegration compared to Ti controls. These findings reveal curvature-degradation coupling effects and establish architectural design principles for biodegradable metal implants.