Advances in coatings on biodegradable magnesium alloys

Manipulating the degradation rate of biomedical magnesium alloys poses a challenge. The characteristics of a microarc oxidation (MAO), prepared in phytic acid, and poly(l-lactic acid) (PLLA) composite coating, fabricated on a novel Mg–1Li–1Ca alloy, were studied through field emission scanning electron microscopy (FE-SEM), electron probe X-ray microanalysis (EPMA), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The corrosion behaviors of the samples were evaluated via hydrogen evolution, potentiodynamic polarization and electrochemical impedance spectroscopy in Hanks’ solution. The results indicated that the MAO/PLLA composite coatings significantly enhanced the corrosion resistance of the Mg–1Li–1Ca alloy. MTT and ALP assays using MC3T3 osteoblasts indicated that the MAO/PLLA coatings greatly improved the cytocompatibility, and the morphology of the cells cultured on different samples exhibited good adhesion. Hemolysis tests showed that the composite coatings endowed the Mg–1Li–1...

In Vitro Corrosion and Cytocompatibility of a Microarc Oxidation Coating and Poly(l-lactic acid) Composite Coating on Mg–1Li–1Ca Alloy for Orthopedic Implants

Research on a Zn-Cu alloy as a biodegradable material for potential vascular stents application.

Magnesium (Mg) and its alloys have been suggested as revolutionary biodegradable materials. However, fast degradation hinders its clinic application. To improve the corrosion resistance and biocompatibility of Mg–Nd–Zn–Zr alloy (JDBM), magnesium–aluminum-layered double hydroxide (Mg–Al LDH) was successfully introduced into Mg(OH)2 coating by hydrothermal treatment. The anions in the interlayer of Mg–Al LDH can be replaced by chloride ions, resulting in a relatively low chloride ion concentration near the surface of the coating. The favorable corrosion resistance of the coating was proved by polarization curves and hydrogen collection test. The Mg–Al LDH significantly promoted cell adhesion, migration and proliferation in vitro. In addition, the coating almost fulfilled the request of the clinical application in the hemolysis ratio test. Finally, in vivo results indicated that the coating offered the greatest long-lasting protection from corrosion and triggered the mildest inflammation comparing to the pur...

Enhanced Corrosion Resistance and Biocompatibility of Magnesium Alloy by Mg-Al-Layered Double Hydroxide.

In vitro corrosion of as-extruded Mg–Ca alloys—The influence of Ca concentration

Magnesium has been suggested as a revolutionary biodegradable metal for biomedical applications. The corrosion of magnesium, however, is too rapid to match the rates of tissue healing and, additionally, exhibits the localized corrosion mechanism. Thus it is necessary to control the corrosion behaviors of magnesium for their practical use. This paper comprehensively reviews the research progress on the development of representative magnesium based alloys, including Mg-Ca, Mg-Sr, Mg-Zn and Mg-REE alloy systems as well as the bulk metallic glass. The influence of alloying element on their microstructures, mechanical properties and corrosion behaviors is summarized. The mechanical and corrosion properties of wrought magnesium alloys are also discussed in comparison with those of cast alloys. Furthermore, this review also covers research carried out in the field of the degradable coatings on magnesium alloys for biomedical applications. Calcium phosphate and biodegradable polymer coatings are discussed based on different preparation techniques used. We also compare the effect of different coatings on the corrosion behaviors of magnesium alloys substrate.

Xiao-Ming Li

Papers

Magnesium based degradable biomaterials: A review