Electrochemical characterization of albumin protein on Ti-6AL-4V alloy immersed in a simulated plasma solution.

The effect of oxygen and albumin on the electrochemical behavior of a Ti-6Al-4V alloy immersed in a simulated inorganic plasma (SIP) solution was studied with a rotating-cylindrical electrode configuration to focus on the surface/electrolyte reactions. Potentiokinetic scans and electrochemical impedance spectroscopy have been used to characterize the interface by determining the passive current density and capacitance. For the polarization scans, an albumin addition of 37.7 mg/cm(3) to the SIP solution (oxygenated and unoxygenated) decreased the passive current density, indicating a lowering of the corrosive rate. The surface capacitance for the Ti-6Al-4V alloy immersed in a SIP solution averaged 13 microF/cm(2), which transformed after albumin addition (37.7 mg/cm(3)) from a potential independent behavior to the capacitance ranging from 23 to 6 microF/cm(2) with increasing potentials from -800 to 1500 mV(SCE), respectively, indicative of albumin adsorption. Within the same potential range and albumin addition to oxygenated solutions, the capacitances expanded slightly with a similar decreasing trend from 31 to 6 microF/cm(2), although the capacitance depicts an interaction between the hydrated passive film and the adsorbed albumin from -550 to 500 mV(SCE) in which the capacitance plateaued at 15 microF/cm(2). The hydrated porous oxide film results from the porous rutile layer reacting with H(2)O(2) formed as an intermediary component of oxygen reduction at the Ti-6Al-4V surface. The passive film-albumin interaction would affect the processing of titanium alloys in their surface preparation for biocompatibility, as well as determining the reactivity of titanium alloys to proteins.