Magnesium (Mg)-based biomaterials have a high potential as orthopaedic implants due to their excellent biocompatibility, mechanical properties and bio-degradability. However, the rapid corrosion has greatly hindered its widespread clinical application. In the past few years, a variety of biodegradable polymers have been explored for various biomedical applications as corrosion-protective and bioactive coating of Mg implants. However, there has had only limited success in satisfying all the requirements for using Mg as biodegradable implant material. We have recently developed a wet casting approach in fabricating biodegradable polymer coatings on Mg alloys. Unlike conventional dip-coating where the phase separation is induced by evaporation (dry-casting), the phase separation of a polymer solution in wet casting is induced by immersion of the polymer solution in a bath of non-solvent. Our results showed that if the non-solvent is well selected, polymer coatings with tailored morphologies could be formed on the surface of Mg rods. We demonstrate that the these polymer coatings can delay the degradation status of the Mg screw, which thus keeps the fixation strength for a longer time.
