Ultrathin ALD Coatings of Zr and V Oxides on Anodic TiO₂ Nanotube Layers: Comparison of the Osteoblast Cell Growth

The current study investigates and compares the biological effects of ultrathin conformal coatings of zirconium dioxide (ZrO₂) and vanadium pentoxide (V₂O₅) on osteoblastic MG-63 cells grown on TiO₂ nanotube layers (TNTs). Coatings were achieved by the atomic layer deposition (ALD) technique. TNTs with average tube diameters of 15, 30, and 100 nm were fabricated on Ti substrates (via electrochemical anodization) and were used as primary substrates for the study. The MG-63 cell growth and proliferation after 48 h of incubation on hybrid TNTs/ZrO₂ and TNTs/V₂O₅ surfaces was evaluated in comparison to the uncoated TNTs of each diameter. The density of viable MG-63 cells was assessed for all the TNT surfaces, along with the cell morphology and the spreading behavior (i.e., the cell length). The ultrathin coatings retained the original morphology of the TNTs but changed the surface chemical composition, wettability, and cell behavior, whose interplay is the subject of the present investigation. These findings offer interesting views on the influence of the composition of biomedical implant surfaces, triggered by ALD ultrathin coatings on them. The outcomes of this work shed light on the assessment of the biocompatibility of the two different ALD coatings.