Deconstructing In Vitro Corrosion of Pure Mg: Influence of Serum Biomolecules and Phosphate Ions

Abstract

Anomalies have been reported between biocorrosion rates of Mg alloys determined in in vitro and in vivo environments. In vivo environments contain serum biomolecules together with inorganic ions, while in vitro environments typically used for testing may or may not include serum biomolecules. In vitro corrosion testing on pure Mg in a series of electrolyte compositions has identified the influence of different biomolecular and inorganic species on the biocorrosion of pure Mg. Electrochemical analyses and electron microscopy indicate that serum biomolecules tend to accelerate the corrosion of Mg, while phosphate ions in synergy with calcium ions inhibit Mg corrosion. However, serum concentrations >30 vol% in test media lead to decreased corrosion of pure Mg. This indicates that variations in Mg biocorrosion rates seen in in vitro and in vivo media could be attributed to differences in serum concentrations in the respective media.