Zn–Mg–Cu triply periodic minimal surface (TPMS) gradient scaffolds fabricated by selective laser melting with enhanced mechanical, degradation, and osteogenic properties

Zn–Mg–Cu TPMS gradient scaffolds were fabricated by selective laser melting. • Mg 2 Zn 11 and Cu 5 Zn 8 phases contributed to enhanced mechanical properties. • Gradient architecture and PDA coating regulated degradation behavior. • The integrated design improved surface bioactivity and promoted osteogenic differentiation. Biodegradable Zn-based scaffolds have attracted increasing attention for bone repair owing to their moderate degradation rate and favorable biological properties; however, achieving coordinated regulation of mechanical integrity, degradation behavior, and osteogenic activity remains challenging. Zn–Mg–Cu triply periodic minimal surface (TPMS) gyroid scaffolds with a radial pore-size gradient were fabricated by selective laser melting (SLM) and subsequently subjected to NaOH alkali-thermal activation and polydopamine (PDA) coating. The incorporation of Mg and Cu significantly enhanced the mechanical properties of the Zn alloy through solid-solution and second-phase strengthening. Meanwhile, the TPMS gradient porous architecture improved stress distribution and provided spatially graded pathways for electrolyte transport, thereby influencing degradation behavior and ion release characteristics. NaOH alkali-thermal treatment markedly improved surface wettability, and the PDA@Zn alloy scaffolds retained a hydrophilic interface; the complete surface treatment mitigated rapid ion release during the early stage of degradation. The scaffolds exhibited favorable compressive strength, controllable degradation behavior, and enhanced cytocompatibility. ICP-MS measurements revealed distinct Zn 2 + , Mg 2+ , and Cu 2+ release profiles, while the in vitro assays demonstrated favorable cell proliferation, osteogenic differentiation, and extracellular matrix mineralization. These biological responses may be associated with the combined effects of the released ions. Overall, the fabricated scaffolds exhibited favorable mechanical properties and controlled degradation behavior, while the complete surface treatment was associated with improved cytocompatibility and osteogenic activity.