Laser Surface Modification of Rare Earth Containing Magnesium Alloy Through Simulated Body Fluid and Its Impact on Cell Viability

Abstract

Magnesium alloys have a good potential as structural biomaterials for temporary implant applications because of their self-degradation properties and biocompatibility. The surface condition is important for such applications, and lasers are often used to modify the surface characteristics of such components. In this context, the media through which the laser beam passes before reaching the surface to be irradiated is also of interest. In particular, laser irradiation in liquids affects the thermal energy delivery to the surface of the material, which in turns influences the formation of surface structures. In this work, rare earth containing WE54 Mg alloy has been irradiated under air and through a simulated body fluid (SBF) layer using a 500 watt pulsed Nd: YAG laser. As compared to direct laser surface treatment through air, laser irradiation through SBF generates new surface structures and deposition of ions issued from the SBF solution. Scanning electron microscope combined with energy dispersive spectroscopy (EDS) was used for the examination of surface structures formation and determination of elemental composition. Mesenchymal stem cells (MSC) culture was performed on laser modified WE54 alloy surface, and the MSC cytocompatibility on SBF-treated substrates was evaluated by the PrestoBlue™ assay test method. Cell reproducibility was observed on the SBF laser-treated surface which indicated that cell viability was improved by the surface treatment. The deposition of calcium and phosphorus ions on the WE54 surface was beneficial for cell viability. These results motivate the potential use of SBF-based films for biomedical purposes.