Improved biological performance of magnesium by micro-arc oxidation

Abstract

Magnesium and its alloys have recently been used in the development of lightweight, biodegradable implant materials. However, the corrosion properties of magnesium limit its clinical application. The purpose of this study was to comprehensively evaluate the degradation behavior and biomechanical properties of magnesium materials treated with micro-arc oxidation (MAO), which is a new promising surface treatment for developing corrosion resistance in magnesium, and to provide a theoretical basis for its further optimization and clinical application. The degradation behavior of MAO-treated magnesium was studied systematically by immersion and electrochemical tests, and its biomechanical performance when exposed to simulated body fluids was evaluated by tensile tests. In addition, the cell toxicity of MAO-treated magnesium samples during the corrosion process was evaluated, and its biocompatibility was investigated under in vivo conditions. The results of this study showed that the oxide coating layers could elevate the corrosion potential of magnesium and reduce its degradation rate. In addition, the MAO-coated sample showed no cytotoxicity and more new bone was formed around it during in vivo degradation. MAO treatment could effectively enhance the corrosion resistance of the magnesium specimen and help to keep its original mechanical properties. The MAO-coated magnesium material had good cytocompatibility and biocompatibility. This technique has an advantage for developing novel implant materials and may potentially be used for future clinical applications.

Improved <em>in Vitro</em> Test Procedure for Full Assessment of the Cytocompatibility of Degradable Magnesium Based on ISO 10993-5/-12

“…Moreover, on basis of the present results, it becomes very clear that the phosphate-base coating variants outperform the silicate-based coating variants. In this context, it has already been described by Ma et al that ceramization with phosphate-based electrolytes allowed a better corrosion resistance of magnesium than those produced from silicate (19). Altogether, the results of this initial biomaterial testing series showed that only 4 phosphate-ceramized materials, WE43-PEO5, WE43-PEO8, WE43-PEO9 and WE43-PEO10, could be selected from the total number of PEO variants based on their superior properties as eligible materials for implants.…”

In vivo Study on the Corrosion Behavior of Magnesium Alloy Surface Treated with Micro‐arc Oxidation and Hydrothermal Deposition

“…However, the degradation process of Mg alloy is too rapid and can generate hydrogen during early implantation in vivo , which does not meet the clinical needs on bone healing. It has been reported that the mechanical integrity of magnesium alloy is only maintained for 6–8 weeks, with the release of hydrogen during the corrosion process. At present, the hot spots and difficulties are focused on how to improve the corrosion resistance of the Mg alloy.…”

“…The approach of surface coating on Mg alloy to improve its corrosion resistance has been accepted by the majority of researchers. The application of micro‐arc oxidation (MAO) to form a magnesium oxide (MgO) layer is considered a feasible way to form a protective coating on Mg alloy, but the protective effect is limited. Hydroxyapatite (HA) is a Ca‐P biocaramic with poor biodegradation, so HA coating is a feasible way to protect basic material from being rapidly degraded.…”

Effect of strontium ions on calcification of preosteoblasts cultured on porous calcium- and phosphate-containing titanium oxide layers formed by micro-arc oxidation

“…Compared with other surface modification methods, the MAO treatment procedure employed in this study was a simple and easy way of producing Ti oxide surface coating layers containing specific target metal elements with the microporous structure. The microporous structures deposited on substrate surfaces by MAO can be controlled by varying operating voltage and current values 11,13) ; for example, a higher voltage leads to a larger pore diameter. In this study, the consistent conditions of the MAO treatment were used, except for the Ca and Sr concentrations.…”

“…As was previously reported, Sr ions have been shown to enhance bone collagen synthesis and decrease bone resorption by inhibiting osteoclast resorbing activity [13][14][15][16][17][18][19][20] . Therefore, it is expected that a local release of Sr ions from implant surfaces would directly improve implant osseointegration.…”