Characterisation of nanotubular TiO-2 films on Ti-6AI-4V alloy for biomedical applications

摘要

TiO-2 nanotube films are of increasing interest for biomedical implant applications as an alternative to surface treatments with micrometer-scale topography. As studies on titanium show, TiO-2 nanotube films offer enhanced cell interactions and possibility of controlled drug loading and delivery for stimulation of bone growth. The majority of TiO-2 nanotube research has been done on c.p. titanium. On the other hand, formation of titanium oxide nanotubes on high strength titanium alloys used for load-bearing prosthetic applications has been far less studied. In these applications the reduction of the probability of infection during surgery and healing process is one of the primary goals. In the last years ion incorporation into titanium surface has been considered of interest in order to provide antibacterial properties to the surface. In the present work fluorine incorporation from the bath utilised to grow self-organised TIO-2 nanotubes was investigated on Ti-6AI-4V alloy. Two types of oxide films with a diameter of 20 and 100 nm and thickness of -100 and 350 nm were grown in acidic fluorine containing solution at 20 V under DC control for 5 and 60 min at 20°C. The morphology, stoichiometry and microstructure of the obtained nanotubes were characterised by scanning electron, transmission electron microscopy, energy-dispersive X-ray spectrometry and Rutherford backscattering analysis. The electrochemical stability and corrosion mechanism of the nanotube oxide films were investigated using cyclic potentiodynamic polarisation and electrochemical impedance spectroscopy during immersion in phosphate buffer solution at 37±1°C up to 3 weeks. Fluorine content, nanotube morphology, microstructure and corrosion resistance are discussed with respect to their optimisation for potential antibacterial coatings.