Degradation Resistance and In Vitro Cytocompatibility of Iron-Containing Coatings Developed on WE43 Magnesium Alloy by Micro-Arc Oxidation

Rongfa Zhang,Shufang Zhang,Guoqiang Li,Zhiyong Chen,Yuanyuan Zhu,Ying Zhao,Rongfang Zhao,Zeyu Zhang,Xiaoting Shi

doi:10.3390/coatings10111138

Abstract

Iron (Fe) is an important trace element for life and plays vital functions in maintaining human health. In order to simultaneously endow magnesium alloy with good degradation resistance, improved cytocompatibility, and the proper Fe amount for the body accompanied with degradation of Mg alloy, Fe-containing ceramic coatings were fabricated on WE43 Mg alloy by micro-arc oxidation (MAO) in a nearly neutral pH solution with added 0, 6, 12, and 18 g/L ferric sodium ethylenediaminetetraacetate (NaFeY). The results show that compared with the bare Mg alloy, the MAO samples with developed Fe-containing ceramic coatings significantly improve the degradation resistance and in vitro cytocompatibility. Fe in anodic coatings is mainly present as Fe2O3. The increased NaFeY concentration favorably contributes to the enhancement of Fe content but is harmful to the degradation resistance of MAO coatings. Our study reveals that the developed Fe-containing MAO coating on Mg alloy exhibits potential in clinical applications.

Highlights

Due to the similar specific density and Young’s modulus to natural bone, and many Mg ion-associated biological functions in vivo, magnesium alloy is believed to be excellent for biodegradable metallic implants [1,2,3]
The properties of Micro-arc oxidation (MAO) coatings are determined by several factors including substrate materials [7] and electrolyte composition and concentration, as well as electrical parameters [3]
Due to the long-term temperature stability, very good mechanical property, and low toxicity of rare earth elements, WE43 alloys are widely used as biomedical Mg alloys [1,8]

Summary

Introduction

Due to the similar specific density and Young’s modulus to natural bone, and many Mg ion-associated biological functions in vivo, magnesium alloy is believed to be excellent for biodegradable metallic implants [1,2,3]. The degradation resistance of Mg alloy can be improved by using alloying, surface treatment, or mechanical processing [1,2]. Micro-arc oxidation (MAO), known as plasma electrolytic oxidation, is an innovative surface treatment method for Mg alloy and titanium alloy [1,4,5,6]. MAO treatment significantly improves the degradation resistance and wear resistance of Mg alloy, and produces multiple biofunctional ceramic coatings [3]. The properties of MAO coatings are determined by several factors including substrate materials [7] and electrolyte composition and concentration, as well as electrical parameters [3]. During MAO, the electrolyte composition and concentration significantly determine coating properties by affecting

Results

Discussion

Conclusion