In vitro degradation of ZM21 magnesium alloy in simulated body fluids

Agnieszka Witecka , Agnieszka Bogucka , A. Yamamoto , K. Mathis , T. Krajnak , Jakub Jaroszewicz , Wojciech Święszkowski

Abstract

In vitro degradation behavior of squeeze cast (CAST) and equal channel angular pressed (ECAP) ZM21 magnesium alloy (2.0 wt% Zn-0.98 wt% Mn) was studied using immersion tests up to 4 w in three different biological environments. Hanks' Balanced Salt Solution (Hanks), Earle's Balanced Salt Solution (Earle) and Eagle minimum essential medium supplemented with 10% (v/v) fetal bovine serum (E-MEM + 10% FBS) were used to investigate the effect of carbonate buffer system, organic compounds and material processing on the degradation behavior of the ZM21 alloy samples. Corrosion rate of the samples was evaluated by their Mg2 + ion release, weight loss and volume loss. In the first 24 h, the corrosion rate sequence of the CAST samples was as following: Hanks > E-MEM + 10% FBS > Earle. However, in longer immersion periods, the corrosion rate sequence was Earle > E-MEM + 10% FBS ≥ Hanks. Strong buffering effect provided by carbonate buffer system helped to maintain the pH avoiding drastic increase of the corrosion rate of ZM21 in the initial stage of immersion. Organic compounds also contributed to maintain the pH of the fluid. Moreover, they adsorbed on the sample surface and formed an additional barrier on the insoluble salt layer, which was effective to retard the corrosion of CAST samples. In case of ECAP, however, this effect was overcome by the occurrence of strong localized corrosion due to the lower pH of the medium. Corrosion of ECAP samples was much greater than that of CAST, especially in Hanks, due to higher sensitivity of ECAP to localized corrosion and the presence of Cl−. The present work demonstrates the importance of using an appropriate solution for a reliable estimation of the degradation rate of Mg-base degradable implants in biological environments, and concludes that the most appropriate solution for this purpose is E-MEM + 10% FBS, which has the closest chemical composition to human blood plasma.
Author Agnieszka Witecka ZPM
Agnieszka Witecka,,
- Division of Materials Design
, Agnieszka Bogucka WA
Agnieszka Bogucka,,
- Faculty of Architecture
, A. Yamamoto
A. Yamamoto,,
-
, K. Mathis
K. Mathis,,
-
, T. Krajnak
T. Krajnak,,
-
, Jakub Jaroszewicz WIM
Jakub Jaroszewicz,,
- Faculty of Materials Science and Engineering
, Wojciech Święszkowski ZPM
Wojciech Święszkowski,,
- Division of Materials Design
Journal seriesMaterials Science & Engineering C-Materials for Biological Applications, ISSN 0928-4931
Issue year2016
Vol65
Pages59-69
Publication size in sheets0.5
Keywords in EnglishZM21 magnesium alloy; ECAP; Simulated body fluids; In vitro degradation
DOIDOI:10.1016/j.msec.2016.04.019
URL http://www.sciencedirect.com/science/article/pii/S0928493116303174
Languageen angielski
Score (nominal)30
ScoreMinisterial score [Punktacja MNiSW] = 30.0, 28-11-2017, ArticleFromJournal
Ministerial score (2013-2016) [Punktacja MNiSW (2013-2016)] = 30.0, 28-11-2017, ArticleFromJournal
Publication indicators WoS Impact Factor [Impact Factor WoS]: 2016 = 4.164 (2) - 2016=3.926 (5)
Citation count*0 (2016-09-12)
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