Corrosion resistance and biocompatibility of polydopamine/hyaluronic acid composite coating on AZ31 magnesium alloy

Magnesium (Mg) and its alloys have received widespread attention as implants for orthopedic surgery due to their degradability and appropriate mechanical properties . However, their poor corrosion resistance may lead to a decline of mechanical properties as well as changes in the surrounding microenvironment, which will eventually lead to their failure as implants. In this work, hyaluronic acid (HYA) was immobilized on AZ31 alloy via a mussel-inspired polydopamine (PDA) anchoring layer. The HYA layer closed the cracks caused by the PDA layer. In vitro corrosion behavior of the PDA/HYA composite coating was investigated via potentiodynamic polarization (PDP) and static immersion assay. The corrosion current density of PDA/HYA coating decreased from 8.48×10 −5 A/cm 2 to 5.71×10 −6 A/cm 2 . During immersion, no obvious local alkalization was observed. Large amounts of calcium phosphate deposited on PDA/HYA coating, which enhanced the biological activity. MTT experiments show that the MC3T3-E1 cell survival rate of polydopamine coating exceeds 100% after cultivated for 5 days. It was found that the number of cells spreading on the surface of PDA/HYA composite coating was the most after the cell culture directly on the surface.