Investigating the role of WEDM surface texturing in the degradation and biocompatibility of Mg–Zn–Ca alloy

Magnesium (Mg) alloy-based biodegradable implants are gaining popularity for their low density, high strength, and biocompatibility. The corrosion and wear performance of Mg is poor in physiological environments, leading to premature failure. Surface modification, particularly through surface texturing, reduces the effective contact area of Mg-Zn-Ca alloy with corrosive media and tribological partners, potentially optimizing its degradation kinetics and cytocompatibility. Wire Electric Discharge Machining (WEDM) offers a stable oxide layer on the surface, unlike laser surface texturing, which may thermally damage the Mg alloy. In this study, three types of textures, mainly Wavy Texture (WT), microchannels (MC), and micropillars (MP), were created using WEDM on the Mg-Zn-Ca samples, and their corrosion, wear, cytotoxicity, and cell adhesion performance were evaluated. Texturing on the surface of the samples enhanced the corrosion performance, from 3.14 mm/year for the untextured sample to 0.98 mm/year for the micropillar textured sample, representing a 68.8% reduction. This improvement after texturing is attributed to the superior surface finish (1.049 μm) and increased hydrophobicity (130.3°), equating to a 50.8% improvement. The coefficient of friction (COF) value decreased from 0.364 for an untextured sample to 0.208 for microchannels, a 42.9% reduction, due to the entrapment of debris in the textures and effective heat transfer. The samples' cell adhesion and cell viability have been improved after texturing. The combination of cytocompatibility, appropriate mechanical properties, and a reduced bio-corrosion rate highlights the potential of this surface texturing method, utilizing WEDM, as a promising approach to enhance biodegradable implant materials.