Growth and electrochemical stability of self-organized TiO2nanotubes on Ti-2 grade and orthopedic Ti6Al4V alloy for biomedical application

Abstract

Titanium and its alloys are biomaterials used in endosseous implants, due to desirable mechanical properties, high corrosion resistance and biocompatibility. Using electrochemical anodization technique these materials can be recovered with self-organized TiO2 nanotubes layer resulting in increased specific surface area and probable bioactivity improvement. This research aimed determine potentiostatic anodization parameters to obtain self-organized TiO2nanotubes layer with reproducibility and ideal diameters for probable bioactive response on Ti - 2 grade (ASTM F67) and Ti6Al4V (ASTM F136) orthopedic alloy and evaluation the electrochemical stability behavior in simulated body fluid media. The self-organized nanotubes layer were obtained by potentiostatic electrochemical method in electrolyte containing fluoride ions, H3PO4/HF for Ti 2 grade and H3PO4/NH4F for Ti6Al4V alloy, the applied potentials were 15 V, 20 V and 25 V for 30, 60 and 90 minutes, for both materials. For morphologic characterization were employed scanning electron microscopy SEM and the Image J software for nanodiameter measurements. The nanoestructure electrochemical stability was evaluated by open circuit potential after immersion for 15, 30 and 60 days in artificial blood plasma, into an electrochemical cell, using SCE (saturated calomel electrode) as reference electrode, in PBS ((phosphate buffered saline) solution electrolyte for 90 minutes. The ideal anodization parameters were 15 V and 20 V for 1 hour and a reproducible, uniform and homogeneous self-organized nanotubes layer were obtained with ideal diameters that probably improve the implant superficial bioactivity with 80 and 120 nm respectively, according to the literature. Open-circuit potentials from metal/oxide system obtained on both materials are stable with potentials in range of -0.031 V to -0,183 V indicating good stability of nanoestructures in simulated body fluid. Nanotubes layer as a superficial treatment is viable with high reproducibility, low cost and electrochemical stability in simulated body fluid media.