Preparation of Hydroxyapatite/Tannic Acid Coating to Enhance the Corrosion Resistance and Cytocompatibility of AZ31 Magnesium Alloys

Bowu Zhu,Jun Liang,Yang Yang,Shimeng Wang,Baocheng Cao,Lei Wang

doi:10.3390/coatings7070105

Bowu Zhu, Jun Liang + Show 4 more

Open Access

https://doi.org/10.3390/coatings7070105

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Abstract

Hydroxyapatite/tannic acid coating (HA/TA) were prepared on AZ31 magnesium alloys (AZ31) via chemical conversion and biomimetic methods. The characterization and properties of the coating were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), corrosion testing, MC3T3-E1 cell proliferation assay, and MC3T3-E1 cell morphology observation. The results showed that tannic acid as an inducer increased the number of nucleation centers of hydroxyapatite and rendered the morphology more uniform. Compared to bare AZ31 magnesium (Mg) alloys (Ecorr = −1.462 ± 0.006 V, Icorr = (4.8978 ± 0.2455) × 10−6 A/cm2), the corrosion current density of the HA/TA-coated magnesium alloys ((5.6494 ± 0.3187) × 10−8 A/cm2) decreased two orders of magnitude, and the corrosion potential of the HA/TA-coated Mg alloys (Ecorr = −1.304 ± 0.006 V) increased by about 158 mV. This indicated that the HA/TA coating was effectively protecting the AZ31 against corrosion in simulated body fluid (SBF). Cell proliferation assays and cell morphology observations results showed that the HA/TA coating was not toxic to the MC3T3-E1 cells.

Highlights

Compared with other metal materials for the current clinical application, magnesium alloys have some good advantages, such as their recoverability, lightweight nature, good mechanical strength, and good resistance against electromagnetic waves [1,2,3,4]
Our work explores the possibility of preparing hydroxyapatite coatings on the surface of AZ31 magnesium alloys with the assistance of tannic acid via biomimetic mineralization, and further improves the corrosion resistance and cytocompatibility of magnesium alloys
The hydroxyapatite/tannic acid coatings on AZ31 magnesium alloys are successfully prepared by chemical conversion and biomimetic method

Summary

Introduction

Compared with other metal materials for the current clinical application, magnesium alloys have some good advantages, such as their recoverability, lightweight nature, good mechanical strength, and good resistance against electromagnetic waves [1,2,3,4]. Their elastic modulus is similar to natural bone tissue and can prevent the occurrence of stress shielding effects to facilitate the healing of bone tissue [2]. Magnesium alloys have good biodegradable properties, which can avoid surgical removal of implants at the end of the treatment. Magnesium alloys have a very negative potential and poor corrosion resistance, which influences bone bonding and suppresses their development for biomedical applications [7]

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