Elsevier

Materials Letters

Volume 265, 15 April 2020, 127349
Materials Letters

One-step in situ synthesis of nano silver-hydrotalcite coating for enhanced antibacterial and degradation property of magnesium alloys

https://doi.org/10.1016/j.matlet.2020.127349Get rights and content

Highlights

  • Ag-LDH coating was prepared by one-step hydrothermal reaction onto magnesium alloy.

  • The coating improved antibacterial and degradation property of alloy substrate.

  • The study provides facile preparation of functional coating onto magnesium alloy.

Abstract

The nano-silver/Mg-Al hydrotalcite (Ag-LDH) functional coating was prepared onto magnesium alloy by one-step hydrothermal reaction for improving its antibacterial and degrading property. The properties of coating involving microstructure, composition, in vitro degradation, cytocompatibility and antibacterial were also studied. The results show that the nano silver particles and hydrotalcite coating were in-situ formed from the alloy surface during the reacting process. Additionally, the pH variation and antimicrobial test reveal that the fabricated Ag-LDH coating can effectively suppress the degradation of the matrix and significantly inhibit the proliferation of Escherichia coli and Staphylococcus aureus, which is with great potential to improve functionality and corrosion resistance of biomedical magnesium alloy.

Introduction

Magnesium and its alloys have been greatly paid attention as a hot spot for biomedical fields because of the advantages such as low density, proper elastic modulus, bio-degradation and excellent biocompatibility [1]. However, its inferior property of corrosion resistance, one prominent problem, has always limited the extensive application especially for clinic bone implants. Surface modification by ceramic, an effective method for surface modification of magnesium alloys, can significantly improve its corrosion resistance, biocompatibility and functionality without affecting the bulk properties [2]. Particularly, Layered Double Hydroxide (LDH), one type of ceramic coating with interlayer structure, is of significant capability to improve and enhance the corrosion resistance of magnesium alloys through the presence of anions and impacting corroding process of matrix metal [3], [4]. It has also been reported that the LDH was with various functions, such as drug delivery carrier [5], bone repair materials [6] and so forth.

On the other hand, the postoperative infection of implants has always been one of the urgent problems to be solved for clinical orthopedic surgery [7]. It has been reported that the postoperative infection rate of orthopaedic prosthesis implants can reach up to 4% [8], and that of open fractures even exceeds 30% [9]. Traditionally, antibiotics used after surgery usually lead to the increment of drug-resistant bacteria, while comparatively the modification to the surface of implants for antimicrobial properties may be more effective. Specifically, recent studies have shown the feasibility of silver nanoparticles to prepare antibacterial coatings onto surfaces of medical metals, such as titanium and magnesium alloys [10], [11], [12], because of highly effective antibacterial and helpfully promoting regeneration of soft tissues [13]. However, the preparing procedures for obtaining Ag-contain coating have generally been complicated [10], [14], and few reports were focused on how to obtain Ag/LDH functional coating peculiarly by simple and facile methods. In this study, the coating of Ag-LDH will be prepared by hydrothermal method onto the surface of magnesium alloy. The microstructure and composition of the coating were systematically characterized and its in vitro degradation as well as antimicrobial properties were also investigated.

Section snippets

Experimental

The magnesium alloy of Mg-3Zn-0.5Zr-0.5Sr alloy (Φ8 × 3 mm) were finely polished, cleaned and dried. Then, the LDH and Ag-LDH coatings were prepared on magnesium alloy by a hydrothermal method, respectively. (For all the detailed experiments see the Supporting Information.)

Results and discussion

Fig. 1a shows the surface morphology of Ag-LDH and LDH coatings and the similitude of these samples morphologies are observed at both low and high magnification. Compared with the LDH coating, there are no apparent particles of nano Ag adhering to the LDH nanosheets as displayed in the Ag-LDH graph probably due to the smaller size of particles, but the presence of Ag element is detected through the corresponding EDS spectra in Fig. 1b. Meanwhile, the results in Fig. 1c show that the

Conclusion

In this study, hydrotalcite coating containing silver nanoparticles was successfully prepared on the Mg alloy surface by one-step hydrothermal reaction. The coating can inhibit the over-fast degradation of metal matrix and silver nanoparticles performed the better antibacterial function and activity against E. coli and S. aureus, which may provide the reference for facile preparation process and design of functional coating onto magnesium alloy.

CRediT authorship contribution statement

Yun Zhao: Conceptualization, Writing - original draft, Writing - review & editing, Visualization, Formal analysis. Yangping Chen: Methodology, Formal analysis, Resources. Wei Wang: Methodology, Formal analysis, Resources, Conceptualization. Zhiyu Zhou: Methodology, Investigation. Shuxin Shi: Methodology, Investigation. Wei Li: Conceptualization, Supervision. Minfang Chen: Conceptualization, Supervision, Project administration. Ze Li: Resources.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by National Nature Science Foundation of China (51801137, 51871166 and U1764254), and Tianjin Natural Science Foundation (117JCQNJC03100).

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