The combined effect of hydroxyapatite and zirconia coatings on magnesium-based-implant to improve corrosion resistance and induce antibacterial activity

In this research, zirconium has been used in two methods of, single-step and double-step, to improve the anti-corrosion properties of Hydroxyapatite (HA) coating. The corrosion behavior of the samples and the performance of the coatings in the physiological environment were investigated by EIS and DC polarization tests in 3.5 wt% sodium chloride and SBF solution, respectively. The results of the electrochemical assays showed that the best resistance against corrosion and biocorrosion is obtained for the sample prepared by the double-step method (HAopt/Zropt sample). FE-SEM and XRD were used to examine the morphology and composition of the coatings that confirmed the formation of HA crystals and the amorphous zirconium layer. According to the antibacterial results, HA/zirconia coating provided a remarkable antibacterial performance (RP =99.9%) against Staphylo-coccus aureus gram-positive and Escherichia coli gram-negative bacteria. Also, HAopt/Zropt sample provided the highest corrosion resistance of about 9000 ohm.cm2 in NaCl, and |Z|0.01 Hz= 3.5 x 105 ohm.cm2 in SBF solution in a prolonged immersion period.