BIOCORROSION RATE AND MECHANISM OF METALLIC MAGNESIUM IN MODEL ARTERIAL ENVIRONMENTS

A new paradigm in biomedical engineering calls for biologically active implants that are absorbed by the body over time. One popular application for this concept is in the engineering of endovascular stents that are delivered concurrently with balloon angioplasty. These devices enable the injured vessels to remain patent during healing, but are not needed for more than a few months after the procedure. Early studies of iron- and magnesium-based stents have concluded that magnesium is a potentially suitable base material for such a device; alloys can achieve acceptable mechanical properties and do not seem to harm the artery during degradation. Research done up to the onset of research contained in this dissertation, for the most part, failed to define realistic physiological corrosion mechanisms, and failed to correlate degradation rates between in vitro and in vivo environments. Six previously published works form the basis of this dissertation. The topics of these papers include (1) a method by which tensile testing may be applied to evaluate biomaterial degradation; (2) a suite of approaches that can be used to screen candidate absorbable magnesium biomaterials; (3) in vivo-in vitro environmental correlations based on mechanical behavior; (4) a similar correlation on the basis of penetration rate; (5) a mid-to-late stage physiological corrosion mechanism for magnesium in an arterial environment; and (6) the identification of corrosion products in degradable magnesium using transmission electron microscopy