Biocompatible and biodegradable functional coatings with natural occurring materials for the corrosion protection of Mg alloys

Abstract

Magnesium alloys are amidst the most innovative materials for biomedical applications, as they show a set of unique properties, namely appropriate mechanical properties and biodegradability, when compared to other alloys. Although these properties make them suitable for medical implants, the main challenge is the uncontrolled corrosion. Mg degradation is fast, inhomogeneous, localized and often accompanied by hydrogen formation which can lead to complications in vivo. Here, we propose the development of a functional coating, containing natural-based capsules for the controlled release of biocompatible corrosion inhibitors and well known pharmaceutical agents. Empty and loaded capsules toxicity tests were performed as a first step for materials selection. Subsequently, they were incorporated into polyetherimide (PEI) coatings and tested using electrochemical impedance spectroscopy (EIS) under aggressive conditions. The obtained results showed a successful synthesis of natural-based microcapsules, constituting a fast, simple and environmentally friendly method. Additionally, the high cell proliferation observed in the presence of the aforementioned materials demonstrates their low toxicity. Preliminary results carried out with capsule-modified coatings show that the incorporation of Ca2+-loaded gelatin capsules in PEI coatings leads to barrier and active corrosion protection properties improvement and that anti-inflammatory agent ibuprofen may have a role in active corrosion protection as well.