Degradation of AZ31 magnesium alloy coated with polydopamine film for bio-resorbable implants

Magnesium and its alloys with their mechanical and biocompatibility features have been attracting a strong interest for the application in the biomaterial field, in particular as bio-resorbable devices. Their main drawbacks are the high reactivity and the formation of gaseous hydrogen when they are in contact with biological fluids. The aim of this work was to evaluate the influence of an intermediate film based on polydopamine on the degradation of the magnesium alloy AZ31 coated with an organic resin, exposed to the Hank’s solution. The morphological analysis of the polydopamine film showed the formation of a macroscopically uneven and microscopically cracked layer. The electrochemical tests, performed in the Hank’s solution at 37 °C, underlined the effect of the presence of dopamine film as an intermediate layer, highlighting the ability to improve the corrosion resistance of the metal substrate when coupled to an organic resin.