A study on the in vitro and in vivo degradation behaviour and biocompatibility of a Mg-Mn-Zn alloy with PLLA and Micro arc oxidation composite coating

The in vitro and in vivo degradation behaviour and biocompatibility of a Mg-Mn-Zn alloy with MAO coating and MAO/PLLA composite coating were studied. The in vitro degradation behaviour was studied by investigating electrochemical behaviour and observing surface morphology for up to 12 weeks and the in vivo degradation behaviour and osteogenic effect were studied by implanting the samples in the mandibles for up to 16 weeks. Both in vitro and in vivo degradation results demonstrated the MAO/PLLA composite coating effectively reduced the degradation rate Mg-Mn-Zn alloy in comparison with MAO coated alloy, while localized degradation was the main degradation form for the coated Mg alloys. In vivo implantation analysis results clearly showed that the MAO/PLLA coated sample exhibited less local osteogenic defects, less bone cavities and less local inflammatory reaction than MAO coated sample. However, more attentions should be paid on the osteogenic defects around the localized corrosion region of the MAO/PLLA coated sample. It was suggested that MAO/PLLA might be an effective coating for the bone implant application of magnesium alloy.