Effects of Surface Treatments on Innovative Additively Manufactured Scaffolds: Implications for Biocompatibility in Bone Tissue Engineering

<b>Purpose</b>: The increasing demand for alternatives to autologous and resorbable bone grafts in the treatment of bone defects is driving research efforts. This study aims to evaluate the effects of different surface treatments on zinc-1%-magnesium (Zn-1Mg) alloy scaffolds on chondrocytes and osteoblasts, focusing on cytotoxicity, biocompatibility, and cell proliferation. <b>Methods</b>: Zn-1Mg alloy disks were manufactured additively by the powder bed fusion of metals using a laser beam (PBF-LB/M) and underwent different distinct surface treatments, including as-built treatment, sandblasting, Zn-1Mg-blasting, and electropolishing, respectively. Chondrocytes and osteoblasts were cultured separately on these additively manufactured Zn-1Mg alloy disks for 3, 7, and 14 days to assess biocompatibility and cellular growth. Cell viability, cytotoxicity, and proliferation were analyzed using DAPI staining, live/dead staining, fluorescence microscopy, and flow cytometry. Additionally, cellular morphology was investigated using Phalloidin/DAPI staining and scanning electron microscopy (SEM). Zn-1Mg scaffolds were also manufactured and subjected to the same surface treatments. All aforementioned experiments were repeated using Zn-1Mg scaffolds with co-cultured osteoblasts and chondrocytes. <b>Results</b>: All samples, irrespective of the surface treatment, showed similar effects compared to the reference surfaces in terms of cell viability, cytotoxicity, and proliferation for both chondrocytes and osteoblasts. SEM analysis revealed comparable cellular morphology across all scaffolds, with cells observed attaching and growing on all scaffold surfaces. This indicates that all scaffolds independent of different surface treatments exhibit good biocompatibility. <b>Conclusions</b>: The findings indicate that Zn-1Mg alloy samples with different surface treatments exhibit no significant differences in cytocompatibility with chondrocytes and osteoblasts. Zn-1Mg alloy scaffolds, composed of 99% zinc and 1% magnesium, demonstrate biocompatibility, with cells attaching and growing on all scaffold surfaces. These results suggest that Zn-1Mg alloy scaffolds manufactured additively by PBF-LB/M hold promise for use in resorbable bone graft applications.