Mechanical properties, degradation behavior, and biocompatibility of porous iron scaffold fabricated by laser powder bed fusion

The design of porous structure can not only improve the degradation rate of iron (Fe) by significantly increasing the specific surface area, but also promote osteogenic differentiation by facilitating nutrient transport and improving cell adhesion. Moreover, biodegradable Fe scaffolds fabricated via laser powder bed fusion (LPBF) present a transformative opportunity to meet the criteria of ideal bone substitutes. This study demonstrates that the optimization of processing parameters and topological design can synergistically enhance Fe scaffolds' performances. By optimizing critical process parameters, near-full densification was achieved. Three topological architectures, namely body-centered cubic (B), diamond (D), and gyroid (G), were manufactured and evaluated for degradation behavior, biomechanical compatibility, and biocompatibility. After 28 days of degradation, all porous scaffolds demonstrated mechanical properties comparable to trabecular bone, effectively mitigating stress shielding risks while maintaining adequate load-bearing capacity. Notably, the G scaffold, which utilized triply periodic minimal surface geometry, exhibited uniform corrosion, progressive failure, and outstanding biocompatibility, achieving over 95 % cell viability in the 50 % extract solution, thus outperforming the B/D scaffolds.