Effect of zinc or copper doping on corrosion resistance and anti-oxidative stress of strontium-based micro-arc oxidation coatings on titanium

In osteoporosis, the osteogenic microenvironment maintains a high level of oxidative stress (OS) due to the overaccumulation of reactive oxygen species (ROS). It not only significantly destroys the bioactivity of titanium (Ti) implants, but also enhances Ti implant corrosion, which has a significant impact on the early osteointegration of Ti implants. In this study, using microarc oxidation (MAO) technology, we constructed strontium/zinc (Sr/Zn)- and strontium/copper (Sr/Cu)-doped MAO coatings on the surface of the Ti implant and studied their corrosion resistance and osteoinductive properties under normal and OS conditions. Apart from their chemical compositions, their physical and chemical properties (roughness, hydrophilicity, morphology, and crystal structure) were similar. In the anti-corrosion test, the MAO-Sr/Zn groups (especially MAO-Sr/Zn3) exhibited perfect performance in both normal and OS microenvironments, whereas MAO-Sr/Cu showed poor corrosion resistance. In terms of biological behavior, based on the perfect osteogenesis and anti-OS properties of Sr and Zn, MAO-Sr/Zn3 exhibited the best performance in terms of cell viability, mineralization, and anti-OS ability, followed by MAO-Sr/Cu2, due to a suitable proportion of Sr/Cu. Therefore the excellent comprehensive performance of MAO-Sr/Zn3 showed that it has broad potential for implant repair in patients with osteoporosis.