Influence of Proteins and Cells on Corrosion of Mg

Mg based materials have been in the focus of increasing interest for temporary biomedical implants, where the device is only required for a certain time of healing. In spite of the large amount of work carried out in  the field, many critical issues still remain, such as limited understanding of the interactions between the corroding Mg (alloy) surface and the biological environment. Results concerning the effects of biomolecules, proteins (and/or) cells on Mg corrosion are scarce and somewhat controversial. For instance, both acceleration or inhibition of Mg corrosion has been reported by proteins in the electrolyte. As the different observations are related to different experimental approaches, it is not straightforward to elucidate the reasons for the seeming discrepancies or the underlying mechanisms.

The presentation will discuss some recent findings on interactions between Mg, proteins (mainly bovine serum albumin), and cells. Protein effects on corrosion were studied by electrochemical techniques on commercially-pure Mg and the Mg alloy AZ91. Surface analysis by XPS and ToF-SIMS indicate that proteins indeed adsorb on Mg surfaces and can inhibit corrosion but the effects are time- and material-dependent. In addition, the presence of proteins in solution change the composition of corrosion layers on the surface. Impedance spectroscopy investigations combined with in vitro cell culturing on Mg demonstrate a significant decrease of dissolution rate after certain time of cell growth.