Abstract
Valve metals such as titanium (Ti), zirconium (Zr), niobium (Nb) and tantalum (Ta) that confer a stable oxide layer on their surfaces are commonly used as implant materials or alloying elements for titanium-based implants, due to their exceptional high corrosion resistance and excellent biocompatibility. The aim of this study was to investigate the bioactivity of the nanostructures of tantala (Ta2O5), niobia (Nb2O5), zirconia (ZrO2) and titania (TiO2) in accordance to their roughness and wettability. Therefore, four kinds of metal oxide nanoporous and nanotubular Ta2O5, Nb2O5, ZrO2 and TiO2 were fabricated via anodization. The nanosize distribution, morphology and the physical and chemical properties of the nanolayers and their surface energies and bioactivities were investigated using SEM-EDS, X-ray diffraction (XRD) analysis and 3D profilometer. It was found that the nanoporous Ta2O5 exhibited an irregular porous structure, high roughness and high surface energy as compared to bare tantalum metal; and exhibited the most superior bioactivity after annealing among the four kinds of nanoporous structures. The nanoporous Nb2O5 showed a uniform porous structure and low roughness, but no bioactivity before annealing. Overall, the nanoporous and nanotubular layers of Ta2O5, Nb2O5, ZrO2 and TiO2 demonstrated promising potential for enhanced bioactivity to improve their biomedical application alone or to improve the usage in other biocompatible metal implants.
Highlights
Metals and alloys that are used as biomaterials have a range of applications in industry and medicine due to their excellent mechanical, physical and chemical properties
Both nanotubular layers fabricated on the zirconium and titanium surfaces are hydrophilic, the ZrO2 nanotubes exhibited a lower water contact angle in comparison to TiO2 with nearly the same distribution of Di (C−F = 0.5 wt %, 10 V), which led to a high surface energy
Electrochemical experiments were performed at room temperature with the electrolyte composed of 1 M H2SO4 + 3.3 wt % NH4F for tantalum and niobium at 20 V for 120 min and
Summary
Metals and alloys that are used as biomaterials have a range of applications in industry and medicine due to their excellent mechanical, physical and chemical properties. There are studies on the formation of a nanoporous layer of Nb2O5 by controlling the effects of mixed electrolytes, applied potential and anodization time. These nanoporous layers displayed different range of pore sizes and thickness formed mostly in an acidic electrolyte [15,20,21]. The formation of self-organized sponge-like porous ZrO2 [25] and nanotube oxide layer with different nanoscale sizes and thicknesses [26] has been described in detail along with the effect of changing the condition of electrolyte, applied potential and time of anodization [26,27,28,29,30]. The prime motivation for the current work is to elucidate the influence of the nano characteristics of the surface layer on the bioactivity of the substrate metals
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