Corrosion behavior and biological responses of a double coating formed on the Ti-6Al-4V alloy surface by using thermal oxidation and biomimetic deposition of bismuth-doped CaP

Abstract This study focuses on the functionalized modification of the Ti-6Al-4V alloy substrates widely used by the biomedical sector. For this purpose, a double coating has been used to improve the bioactivity properties of the Ti-6Al-4V alloy by using thermal oxidation followed by Bi-CaP biomimetic deposition. The coated samples were characterized morphologically and structurally by using SEM/EDS, AFM, Raman spectroscopy as well as XRD measurements. EIS technique was used to understand the global electrochemical behavior in Hank’s solution. Interfacial tension theory was used for the determination of the surface free energy of interaction. Regarding the biological assays, cytotoxicity, and biocompatibility tests as well as analyses of inflammatory responses were performed. Our results demonstrated the formation of a double coating containing rutile covered by DCPD and Bi-doped hydroxyapatite. EIS results demonstrated the thermal oxidation method associated with biomimetic deposition promoted an improvement in the corrosive properties of the Ti-6Al-4V alloy, suggesting that the double coating has great potential for biological applications. Finally, the double coating presented a more hydrophilic behavior, and cytotoxicity, biocompatibility, and inflammatory tests responses showed that the Bi-CaP reduced both Ti-6Al-4V alloy toxicity and its inflammation induction besides increasing the anti-inflammatory cytokine levels.