Effect of hydrogen peroxide on titanium surfaces: in situ imaging and step-polarization impedance spectroscopy of commercially pure titanium and titanium, 6-aluminum, 4-vanadium.

To analyze titanium's response to representative surgical wound environments, a study was conducted on commercially pure titanium (CPTi) and titanium, 6-aluminum, 4-vanadium (Ti-6Al-4V) exposed to phosphate-buffered saline (PBS) with 30 mM of hydrogen peroxide (H(2)O(2)) added. The study was characterized by simultaneous electrochemical atomic force microscopy (EC AFM) and step-polarization impedance spectroscopy (SPIS). Surfaces were covered with protective oxide domes that indicated topography changes with potential and time of immersion. Less oxide dome coarsening was noted on surfaces treated with PBS containing H(2)O(2) than on surfaces exposed to pure PBS. Electrical data deduced from current transients collected while stepping voltage between 0 V and 1 V indicated that charge transfer in hydrogen peroxide solutions was an order of magnitude larger than it was in pure PBS. Oxide (early) resistances of CPTi samples were higher than were Ti-6Al-4V oxide resistances in both types of solutions, but CPTi oxide resistance was lower in the hydrogen peroxide solution compared to pure PBS. Capacitance data suggest that CPTi oxide films thicken in hydrogen peroxide solution more than they do in pure PBS. Differences in electrical properties between CPTi and Ti-6Al-4V surfaces suggest that CPTi, but not Ti-6Al-4V, has catalytic activity on H(2)O(2) and that the catalytic activity of CPTi oxide affects its ability to grow TiO(2). Differences in electrical properties are related to catalytic and oxidative mechanisms that take place directly on the titanium oxide surface and in wound environments. The study provides a foundation and theoretic basis for the porous oxide model on commercially pure titanium exposed to hydrogen peroxide.