Enhancing degradation behaviour, osteogenic capacity and angiogenic performance of additively manufactured porous Zn-Mg scaffold via a neobavaisoflavone-doped GelMA composite hydrogel coating

Additively manufactured Zn alloy porous implants hold remarkable potential and promise for bone defect repair, owing to their customizable structures and biodegradable features. However, the porous nature enlarges their exposed surface area, rendering them release excessive Zn2+, which is harmful to osteogenesis and angiogenesis. In this study, a neobavaisoflavone (NBIF)-doped gelatin methacrylate (GelMA) composite hydrogel coating was prepared on the Zn-Mg porous scaffold fabricated by laser powder bed fusion. The coating characteristics, degradation behaviour, and cell responses were systematically investigated. The results indicated that a stable coating with thickness of approximately 20 μm was chemically bonded to the scaffold surface. Moreover, NBIF were anchored within GelMA matrix, enhancing its structural integrity and stability. This NBIF-doped hydrogel coating significantly decelerated the release kinetics of Zn2+. After immersion, the coated scaffold maintained favourable mechanical properties, with a compressive strength of 46.11 MPa and an elastic modulus of 1.84 GPa. Furthermore, the coated scaffold exhibited superior biocompatibility and osteogenic properties, as evidenced by the upregulation of COL1, OCN, RUNX2 and ALP genes, and also demonstrated enhanced angiogenic capabilities. In the in vivo testing, significantly improved bone repair capacity for the coated scaffold were observed, indicating a promising candidate for bone repair applications.