Effect of cathode material on the morphology and osseointegration of TiO2 nanotube arrays by electrochemical anodization technique

Titanium (Ti) has been one of the most widely used materials for biomedical implants owing to its suitable bulk and surface properties. To control the risk of tissue infection and implant failure, titanium dioxide nanotubes (TNTs) have been frequently grown on Ti surface via electrochemical anodization (EA), which is a cost-effective process offering tunable TNTs structures with ease. In the present work, the role of counter electrodes in affecting the microstructure and surface properties of TNTs was investigated. To study this less-highlighted parameter systematically, platinum (Pt), graphite (Gp), and stainless steel (SS) were selected as representatives. The use of Pt and Gp cathodes led to TNTs with typical circular morphology, while those produced with the SS cathode displayed hexagonal-shaped tubes. Moreover, TNTs fabricated with SS cathode exhibited particle debris on the surface at the expense of some portion of its tube length. This morphology, however, resulted in greater surface roughness and hydrophilicity. The highly complicated surface microstructure played a major role in facilitating the growth of bone-forming apatite during osseointegration.