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Surface modification of tantalum via anodization for orthopedic applications

2020
Uslu, Ece
Tantalum has excellent corrosion resistance and mechanical properties suitable for orthopedic applications. However, tantalum exhibits bioinert characteristics and cannot promote desired level of osseointegration with juxtaposed bone tissue. To enhance bioactivity of tantalum, nanoscale surface modification via anodization could be a potential approach. In this study, tantalum foils were modified to obtain surface features with different morphologies, i.e. nanotubular, nanodimple, nanoporous and nanocoral, via anodization. By controlling anodization parameters including voltage, anodization duration, temperature and electrolyte concentration, surface feature sizes were precisely fine-tuned in the range of 20-140 nm. In this thesis, anodized tantalum samples were characterized to investigate physical and chemical properties of their surfaces, i.e. morphology, crystallinity, hydrophobicity, topography and chemistry. The results indicated that anodized tantalum surfaces consisted of Ta2O5 and non-stoichiometric tantalum oxide. Upon the anodization, surface area of the tantalum samples increased up to 2 folds, which was accompanied by up to 3.5 folds increase in the nanophase surface roughness. Initial results indicated enhanced fibroblast proliferation and spreading on nanoporous tantalum surfaces in vitro. In line with that study, anodized nanotubular, nanodimple and vi nanocoral tantalum and non-anodized tantalum surfaces were interacted with bone cells in vitro. Biological studies showed that anodized tantalum surfaces significantly enhanced protein adsorption and, at the same time, improved bone cell proliferation and spreading in vitro independent of the anodized surface morphology and feature size.