Proceedings of MSSM2018, 07-10 Aug 2018, UWS, Paisley, UK BIOCOMPATIBLE AND BIODEGRADABLE FUNCTIONAL COATINGS WITH NATURAL OCCURRING MATERIALS FOR THE CORROSION PROTECTION OF MG ALLOYS I. Sousa 1 , C.S. Neves 1 , S. Fraga 2,3 , J.P. Teixeira 2,3 , N. Scharnagl 4 , M.L. Zheludkevich 4 , M.G.S. Ferreira 1 and J.Tedim 1 1. CICECO/DEMaC, Universidade de Aveiro, 3810-193 Aveiro, email: isabel.sa.correia@ua.pt. 2. EPIUnit Instituto de Saúde Pública, Universidade do Porto, 4050-091 Porto, Portugal. 3. Departamento de Saúde Ambiental, Instituto Nacional de Saúde Doutor Ricardo Jorge, 4000-053 Porto, Portugal. 4. Helholtz-Zentrum Geesthacht Zentrum für Material-und Küstenforschung, Max-Planck Straße 1, 21502 Geesthacht, Germany. 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 Ca 2+ -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. Keywords: encapsulation; natural-based materials; active species; corrosion control. 1 INTRODUCTION Metals have been playing an essential role in several biomedical devices, being more suitable for load bearing applications than ceramic or polymeric materials [1-3]. However, the possible release of toxic products through corrosion processes, can lead to complications that may ultimately require the removal of the implant [4]. An adequate solution for this problem is the use of biodegradable implants but, their insufficient mechanical properties for bone implant application and non-suitable degradation rates [1, 5] are a disadvantage. Magnesium alloys seem to combine the best features of both ceramic and polymeric materials, with their light-weight, low density and mechanical properties, along with biocompatibility and in vivo importance, due to Mg 2+ fundamental role in several metabolic processes, making them more suitable for medical implants. Nevertheless, Mg alloys are prone to uncontrolled corrosion which hinders their application due to H2 evolution and pH increase [6]. Therefore, the use of Mg alloys requires a control over its degradation rate in order to allow the body to gradually deal with products resulting from corrosion [2]. Protective coatings have been used in different applications in corrosion engineering. Often, corrosion inhibitors can be added to the coating matrix to impart active protection, but leaching of inhibitors and negative reaction between the coating matrix and these species are potential limitations. This problem has been tackled by the encapsulation of inhibitors in inert capsules before their introduction into coating formulations [8]. Although successful in different areas such as aeronautical industry, this strategy has never been truly implemented in the control of degradation processes of biomaterials by corrosion, with only a few reports of synthetic polymers [5, 9] used as biodegradable coatings for Mg-based alloys being available. The main innovation of this work is the attempt to control the rate of degradation by corrosion of Mg-based implants by controlled release of corrosion inhibiting species and other relevant molecules (for control of infectious responses) from bioabsorbable polymer coatings loaded with functional capsules. brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Repositório Institucional da Universidade de Aveiro