Application of a Bioactive Coating on Resorbable, Neodymium Containing Magnesium Alloys, and Analyses of their Effects on the In Vitro Degradation Behavior in a Simulated Body Fluid

Whilst bioactive coatings are commonly used as layers for non-resorbable implant materials, such as titanium or steel to improve cell adhesion, this study investigates the application of bioactive SiO2–CaO–P2O5 on resorbable magnesium alloys (Nd2 and LANd442). The bioactive coating was applied to the magnesium alloys by a dip-coating process, where a parameter set of 20 immersions and a 10 s drying time between each immersion generated a reproducible layer with regard to its thickness and homogeneity. In vitro mass loss, strength loss, and pH value measurements were used to determine the coating's effects on the degradation behavior in a simulated body fluid. Here, it could be observed that bioactive layers on magnesium alloys lead to an increased degradation in comparison to specimens in the uncoated states. In addition to this, pitting corrosion was determined for bioactive coated magnesium samples during comparatively early periods of the investigation. Due to the decreased corrosion resistance and induced pitting corrosion of bioactive coated magnesium alloys, it is suggested that one carefully tests if the enhanced cell adhesion, which occurs with bioactive coatings, warrants the increased degradation of magnesium based implant materials.