Unveiling the Interaction of Bowl-Shaped Polydopamine on Ti40Zr for Corrosion Resistance and Augmented Biomineralization Capacity

The surface chemistry of Ti40Zr alloys plays a significant role in the formation of the bowl-shaped morphology of polydopamine (PDA). The bowl-shaped PDA morphology formation mechanism on the metal surface and its potential application in biomineralization and long-term stability as an implant material were investigated systematically. A novel nonsacrificial template-assisted bowl-shaped hollow capsule PDA formation was formed on alkali-treated Ti40Zr. Our research hypothesizes that the bowl-shaped hollow structure of PDA is a result of its ion exchange activity. The surface characterization confirms the presence of bowl-shaped hollow capsule PDA and nano-PDA through HRSEM with EDS, contact angle measurement, and XRD for the crystalline phase. The corrosion resistance behavior of PDA-Ti40Zr shows high polarization resistance and enhanced coating stability in SBF which is confirmed in corrosion assessment. The potential surface biocompatibility for bone augmentation was investigated through immersion of PDA-Ti40Zr in Hank's solution for 28 days, and the morphology of the apatite layer indicated dense compact growth and coverage on the surface. The calcium ions increase as the immersion period increases in vitro biomineralization. The quantitative assessment of calcium concentration was performed by alizarin red and ALP activity up to the seventh day. The seventh day of the alizarin red assay results demonstrate that the quantity of calcified nodules increases. The osteogenic marker suggested that the differentiation and mineralization process was accelerated on PDA-Ti40Zr starting from the third day. The results of corrosion studies, bone mineralization assay, and cytocompatibility show promise that the PDA-coated Ti40Zr is a choice material for patients undergoing orthopedic surgery and permanent implantation.