Biodegradation behavior of micro-arc oxidation coating on magnesium alloy-from a protein perspective

Zhao-Qi Zhang; Li Wang; Mei-Qi Zeng; Rong-Chang Zeng; M Bobby Kannan; Cun-Guo Lin; Yu-Feng Zheng

doi:10.1016/j.bioactmat.2020.03.005

Biodegradation behavior of micro-arc oxidation coating on magnesium alloy-from a protein perspective

Bioact Mater. 2020 Mar 30;5(2):398-409. doi: 10.1016/j.bioactmat.2020.03.005. eCollection 2020 Jun.

Authors

Zhao-Qi Zhang^{1

2}, Li Wang², Mei-Qi Zeng¹, Rong-Chang Zeng^{1

3}, M Bobby Kannan⁴, Cun-Guo Lin², Yu-Feng Zheng⁵

Affiliations

¹ Corrosion Laboratory for Light Metals, College of Material Science and Engineering, Shandong University of Science and Technology, Qingdao, 266590, China.
² State Key Laboratory for Marine Corrosion and Protection, Luoyang Ship Material Research Institute, Qingdao, 266101, China.
³ School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450002, China.
⁴ Biomaterials and Engineering Materials (BEM) Laboratory, College of Science, Technology and Engineering, James Cook University, Townsville, 4811, Australia.
⁵ State Key Laboratory for Turbulence and Complex Systems and Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, China.

Abstract

Protein exerts a critical influence on the degradation behavior of absorbable magnesium (Mg)-based implants. However, the interaction mechanism between protein and a micro-arc oxidation (MAO) coating on Mg alloys remains unclear. Hereby, a MAO coating was fabricated on AZ31 Mg alloy. And its degradation behavior in phosphate buffer saline (PBS) containing bovine serum albumin (BSA) was investigated and compared with that of the uncoated alloy. Surface morphologies and chemical compositions were studied using Field-emission scanning electron microscope (FE-SEM), Fourier transform infrared spectrophotometer (FT-IR) and X-ray diffraction (XRD). The degradation behavior of the bare Mg alloy and its MAO coating was studied through electrochemical and hydrogen evolution tests. Cytotoxicity assay was applied to evaluate the biocompatibility of Mg alloy substrate and MAO coating. Results indicated that the presence of BSA decreased the degradation rate of Mg alloy substrate because BSA (RCH(NH₂)COO‾) molecules combined with Mg²⁺ ions to form (RCH(NH₂)COO)₂Mg and thus inhibited the dissolution of Mg(OH)₂ by impeding the attack of Cl‾ ions. In the case of MAO coated Mg alloy, the adsorption of BSA on MAO coating and the formation of (RCH(NH₂)COO)₂Mg exhibited a synergistic effect and enhanced the corrosion resistance of the coated alloy significantly. Furthermore, cell bioactive assay suggested that the MAO coating had good viability for MG63 cells due to its high surface area.

Keywords: Biocompatibility; Degradation; Magnesium alloy; Micro-arc oxidation; Protein.