PhD abstract: Multifunctional Coatings for Biomedical Mg Alloys

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Magnesium (Mg) and its alloys are emerging materials for biomedical applications owing to their desirable mechanical and biological features. However, their clinical applications are significantly restricted by the rapid and uncontrollable degradation progress, which gives rise to hydrogen gas evolution, deterioration of mechanical strength and dramatic changes in local pH in chloride-rich physiological environments. Furthermore, a comprehensive understanding of biocompatibility is essential for design and employment of biomedical Mg implants. In particular, it is of great significance to prevent the implant-related infections caused by dwelling of pathogen colonies and degradation products after implantation. Existing research focuses either on the corrosion or pathogenic issues of Mg-based implants. It is a pressing requirement to discover a feasible solution to such two key issues at the same time.

This project aims to develop a series of gallium (Ga) based multifunctional coatings, which not only suppress the initial degradation kinetics, but also reduce the risk of implants associated infections through sustainable release of antibacterial agents from coatings during the degradation process to surrounding tissues simultaneously.

Though Ga is a recognised broad-spectrum antibacterial element, its use as coating materials for Mg alloys is yet to be assessed. In this study, protective coatings containing Ga ions as germ-killer will be prepared through a cost-effective technique.

Physical, chemical, electrochemical and antibacterial features will be characterised by SEM-EDX, FIB-TEM, XRD, XPS, potentiodynamic polarisation curves, EIS, and in vitro cell and bacteria cultures. It is anticipated that such a new series of coatings will open up new possibilities for clinical applications of degradable Mg alloys.

Ming-Shi Song and the project were supported by ARC Linkage project LP150100343 'Functional Strontium Phosphate Coated Magnesium Alloys For Orthopaedic Use'. Visit the project's grant page on the ARC website for more information.