Plasma surface modification of magnesium alloy for biomedical application

Currently, metals are widely used for load-bearing application due to their combination of high mechanical strength and fracture toughness. However, most conventional metallic materials generally remain in human body permanently, bringing long-term endothelial dysfunction. The corrosion products are also considered potentially harmful to tissues of the human body. In recent years, magnesium (Mg) alloys had caused significant attention due to their outstanding advantages. Mg alloys have mechanical properties similar to bone which avoid stress shielding. They are also biocompatibly essential to the human metabolism as a cofactor for many enzymes. In addition, the corrosion product of Mg is likely to be physiologically beneficial. Most importantly, they are perfectly biodegradable in the body fluid. No material could match perfectly every requirement for a given application. For Mg alloys, the extremely low corrosion resistance in chloride containing environments limits their applications. Interactions between biological environments and biomedical materials take place on the material surface, and the biological response from living tissues to these extrinsic biomaterials depends on the surface properties. Therefore, surface modification to form a hard, biocompatible and corrosion resistant modified layer has recently become an interesting topic in biomaterials.This paper reviews the current research and development status of plasma surface modification technologies of Mg alloy for biomedical materials. The unique advantage of plasma modification is that the surface properties and biocompatibility can be enhanced selectively while excellent bulk properties remain unchanged. This paper discusses the characteristic of different methods. Finally, the scientific challenges are proposed based on our researches and the works done by other groups.