Topology-driven printability, mechanical integrity, and permeability in laser-printed biodegradable Mg scaffolds

Laser powder bed fusion (LPBF)-fabricated biodegradable magnesium (Mg) scaffolds show great promise for bone repair. However, their application is constrained by inherent thermophysical defects in LPBF and the trade-off between mechanical strength and mass transport in porous designs. Here, we fabricated porous Mg scaffolds with two biomimetic architectures, including a triply periodic minimal surface (Gyroid) and a stochastic Voronoi, via LPBF. Results demonstrate that geometry-specific features govern performance specialisation. The Gyroid, owing to uniform heat dissipation across its continuous minimal surface, achieves high dimensional precision and superior compressive strength, exhibiting a layer-by-layer folding deformation that produces a stable undulating plateau. In contrast, the Voronoi architecture, with its stochastic strut network, disperses stress, prevents through-thickness shear banding, and undergoes progressive densification with a smoothly rising plateau. Furthermore, the Voronoi scaffold offers a permeability of 12.5 × 10−8 m2, which falls closest to the physiological range of human cancellous bone, and attains a surface area fraction of ≈25% within the optimal osteogenic wall shear stress window associated with favourable osteogenic conditions, markedly outperforming the Gyroid (≈16%). Our study clarifies the distinct potential application niches of Gyroid and Voronoi scaffolds, providing a basis for the rational design of Mg scaffolds for biodegradable applications.