Surface hydroxylation regulates cellular osteogeneses on TiO₂ and Ta₂O₅ nanorod films

Titanium and tantalum have been widely used for orthopedic and dental implant applications. However, how their inherent surface features regulate cellular osteogeneses still remains elusive. In this study, we engineered two distinct TiO₂ and Ta₂O₅ nanorod films as the two model oxidized surfaces to investigate their intrinsic osteogenic behaviors. The results indicated that the distinctive gradient on zeta potential against pH, corresponding to the deprotonation rate, but not the hydroxyl amount or hydroxylation polarity played a critical role on the cellular osteogenic performance. TiO₂ nanorod film with a higher deprotonation rate significantly upregulated the expression of osteogeneses-related gene and protein, comparing to that of Ta₂O₅ nanorod film. These results might be attributed to that surface with higher deprotonation rateprovided more Bronsted acid-base surface sites to react with protein residues, leading to a mild change in conformation of the absorbed proteins, and subsequently facilitating to trigger the integrin-focal adhesion cytoskeleton actin transduction pathway. This study, therefore, provides a new insight into the understanding the role of material surface hydroxylation on cellular osteogenic responses.