Ultrathin TiO₂ ALD Coatings Enhance Properties of Biomaterials used in Medicine

TiO₂ surfaces are in general recognized as excellent biocompatible materials owing to their resistance to body fluid effects, low ion release, high stability, antibacterial properties, and wetting ability. Various TiO₂ nanostructured surfaces show great properties enhancing cell interactions. Anodic TiO₂ nanotube (TNT) layers have emerged as extremely suitable and effective substrates for cell growth and proliferation. A pioneering study demonstrated that TNTs with a diameter of 15 nm are the most suitable surface for the growth of cells [1]. Several papers also showed that anodization is a great tool for surface modification of various materials used in biomedical applications, especially TiAlV.
Recently, we demonstrated that ultrathin coatings by metal oxides (e.g. TiO₂) using Atomic Layer Deposition (ALD) on TNT layers enhance cell adhesion, growth, and proliferation [2]. These properties make them excellent as the uppermost surfaces for bone and dental implants. The presentation deals with the comparison of the biological effect of ultrathin TiO₂ ALD coatings achieved by various numbers of TiO₂ ALD cycles on planar and nanotubular surfaces. For that Ti sheets and anodized TNT layers with a distinct inner diameter of 12 nm and 15 nm, were used as substrates, as they appear to be the most suitable for cell growth in general. We evaluated the cell adhesion, proliferation, and density of fibroblast, osteoblast, and neuroblast cells on these substrates [2,3].
Moreover, the single-cell adhesion of the cells to the TNT layers modified using ALD method was studied by the bio-Atomic Force Microscopy (bio-AFM) technique [3]. Finally, the biological effect of black form of TiO₂ nanotubes in comparison to their classical counterparts was investigated for the first time. The black TiO₂ nanotubes with TiO₂ ALD coating can be considered as a potential candidate in various applications due to the disappearance of mild toxic effects of white and black TiO₂ nanotubes due to the shading of carbon and fluorine species incorporated within the TiO₂ nanotube walls [4].

References:
1. Park, J., Bauer, S., Schlegel, K. A., Neukam, F. W., von der Mark, K., & Schmuki, P. (2009). TiO₂ nanotube surfaces: 15 nm—an optimal length scale of surface topography for cell adhesion and differentiation. Small, 5(6), 666-671.
2. Motola, M., Capek, J., Zazpe, R., Bacova, J., Hromadko, L., Bruckova, L., ... & Macak, J. M. (2020). Thin TiO₂ coatings by ALD enhance the cell growth on TiO₂ nanotubular and flat substrates. ACS Applied Bio Materials, 3(9), 6447-6456.
3. Baishya, K., Vrchovecká, K., Alijani, M., Rodriguez-Pereira, J., Thalluri, S. M., Goldbergová, M. P., ... & Macak, J. M. (2023). Bio-AFM exploits enhanced response of human gingival fibroblasts on TiO₂ nanotubular substrates with thin TiO₂ coatings. Applied Surface Science Advances, 18, 100459.
4. Sopha, H., Bacova, J., Baishya, K., Sepúlveda, M., Rodriguez-Pereira, J., Capek, J., ... & Macak, J. M. (2023). White and black anodic TiO₂ nanotubes: Comparison of biological effects in A549 and SH-SY5Y cells. Surface and Coatings Technology, 462, 129504.