Page 78 - Magnesium-based supports for stem cell therapy of vascular disease - Mónica Echeverry Rendón

CHAPTER 4
of the system substrate material-anodic coating, where both are disappearing simultaneously, but at a very low rate. This behavior can be used in biomedical application for making temporally implants where a transitional scaf- fold or support is required [34]. These kind of materials are commonly used in orthopedics and cardiovascular fields [35–40]. One of the advantages to use these coatings is that the main components of the anodic film are MgO and Mg(OH)2, which once degraded in the body do not cause adverse effects and are harmlessly excreted in the urine. Contrary, some Mg alloys designed to improve the mechanical properties and the corrosion resistance of Mg, can induce toxicity by the accumulation of some alloys (e.g Aluminum) in the body which can be potentially dangerous inducing diseases such as Alzheimer[41].
Conclusions
Plasma electrolytic oxidation is a technique that allow to improve the corrosion resistance of Mg by the growing of a protective layer in a controlled way. The optimization of the process allowed to obtain homogenous surfaces with a good reproducibility. As product of this study, novel formulations for the anodization of c.p Mg based in the addition of hexamethylenetetramine and mannitol to the electrolytic solution has been developed. Those coatings showed an improvement in the corrosion resistance properties in comparison with other modifications used in the past like fluoride/silicate solutions. In addition as a new improvement, a double coating using the previous formulations was explored. After anodization, the samples changed the properties in terms of surface energy and the coatings transform the material from a hydrophobic behavior of the c.p Mg to hydrophilic. All surface modifications were hemocompatible as well as biocompatible and thus would be promising for rendering c.p Mg suitable for biomedi- cal applications such is the case of bone replacement or cardiovascular implants were biodegradable scaffolds are required.
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