In vitro degradation behavior of Fe–20Mn–1.2C alloy in three different pseudo-physiological solutions Essowè Mouzou a,b , Carlo Paternoster a , Ranna Tolouei a , Agung Purnama a,b , Pascale Chevallier a , Dominique Dubé b , Frédéric Prima c , Diego Mantovani a,b, ⁎ a Laboratory for Biomaterials and Bioengineering, Canada Research Chair Tier I in Biomaterials and Bioengineering for the Innovation in Surgery, Department of Mining, Metallurgy and Materials Engineering, CHU de Quebec Research Center, Laval University, Canada b Department of Mining, Metallurgy and Materials Engineering, Laval University, Canada c PSL Research University, Chimie Paris Tech-CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France abstract article info Article history: Received 18 July 2015 Received in revised form 26 October 2015 Accepted 28 December 2015 Available online 30 December 2015 High manganese austenitic steels such as Fe–20Mn–1.2C alloys are among the most promising candidates for bio- degradable stents applications due to their high strength, high ductility and their chemical composition. In the current work, 14 day static in-vitro tests were performed in controlled atmosphere to assess the degradation be- havior in three common pseudo-physiological solutions, i.e. commercial Hanks' (CH), modified Hanks' (MH) and albumin-enriched Dulbecco's modified phosphate buffered saline (DPBS) solutions. The degraded samples sur- faces as well as the degradation products were characterized by X-ray diffraction (XRD), scanning electron mi- croscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Degradation of material and degradation products are shown to be strongly dependent on the test medium due to the presence of different ionic species such as HCO 3 - , CO 3 2- , Cl - , Ca 2+ or phosphate groups. In both MH and CH solutions, the increased content of HCO 3 - ions seems to promote MnCO 3 crystal growth on sample surfaces whereas the presence of albumin and high content of phosphate ions promotes the formation of an amorphous layer rich in phosphates, iron and manganese. © 2015 Elsevier B.V. All rights reserved. Keywords: Degradable metals Corrosion Degradation Medical devices Metals New alloys Cardio-vascular applications 1. Introduction Among the pathologies affecting the cardiovascular system, athero- sclerosis is undoubtedly one of the most relevant with 7.3 million deaths per year in the world [1]. Significant progresses were made in the treatment of this pathology with the application of angioplasty [2]. A stent is also often deployed in the injured site to provide a mechanical support for the vessel walls [3] and to prevent its further occlusion after surgical treatment. Stents made of metallic materials such as AISI 316L stainless steel and Nitinol offer a solution to the problem of artery block- age. However, a common outcome associated with the use of perma- nent stents is restenosis [4]; this complication can be triggered by the release of toxic ions, for example Ni, which is a common element found in many alloys used in stent fabrication [5]. A new trend in scientific community is based on the evidence that the presence of a stent after the vessel restoration would not provide any further benefits [6]: on the contrary, it may cause additional prob- lems, for example in pediatric patients. For this reason, biodegradable metals [6–8] emerged as a novel class of biomaterials during the last decade. Current studies focus mainly on Mg and Mg-based alloys [9], Fe and Fe-based alloys [10–12] and other metals (Zn, etc.) [13]. Metallic biodegradable materials should display suitable mechanical properties, an appropriate degradation rate matching the healing time of the in- jured vessel and a convenient ion release in term of chemical species, size of debris and general biocompatibility [14,15]. Fe-based alloys [16] have mechanical properties comparable to those of the reference material (AISI 316L stainless steel), but their degradation rate is still considered too slow [10–12]. Therefore, interesting strategies to im- prove the degradation rate are based on addition of alloying elements [10,16–18] and/or on microstructural modifications [19]. Also, im- proved mechanical properties would result in reduced strut thickness; a high ductility is however always needed to withstand the plastic de- formation during the deployment sequence. Recently, high manganese austenitic steels with twinning induced plasticity (TWIP) effect, devel- oped primarily for industrial applications, raised a great interest in the scientific community because of their exceptional combination of high strength and ductility [20]. The low corrosion resistance in chloride- rich environment [21,22] and the presence of Mn, reported as non- toxic for the cardiovascular system [23] for the considered concentra- tions, make this family of materials a promising candidate for use in cardiovascular devices. Different kinds of Fe–Mn based alloys were al- ready investigated by several authors [17,18], in modified Hanks' Materials Science and Engineering C 61 (2016) 564–573 ⁎ Corresponding author at: Laval University, Pav. Adrien-Pouliot, 1065 Ave de la Médecine, Québec, QC G1V 0A6, Canada. E-mail address: Diego.Mantovani@gmn.ulaval.ca (D. Mantovani). http://dx.doi.org/10.1016/j.msec.2015.12.092 0928-4931/© 2015 Elsevier B.V. All rights reserved. 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