The effect of static applied potential on the 24-hour impedance behavior of commercially pure titanium in simulated biological conditions

✍ Scribed by Mark T. Ehrensberger; Jeremy L. Gilbert

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 203 KB
• Volume: 9999B
• Category: Article
• ISSN: 1552-4973
• DOI: 10.1002/jbm.b.31564

✦ Synopsis

Abstract

Potential step impedance analysis was utilized to evaluate the electrochemical impedance of commercially pure titanium (cpTi) samples that were polarized to static potentials (range from −1000 mV to +1000 mV vs. Ag/AgCl) and immersed in physiologically relevant electrolytes [phosphate buffered saline (PBS) and cell culture medium with 10% fetal bovine serum (AMEM + FBS)] for 24 hrs. The cpTi impedance outcomes were a complex function of voltage, solution constituents, and immersion time. In the 0 mV to +1000 mV range, oxide growth was observed over 24 hr immersion in both solutions based on decreasing current density (∼10^−6^ A/cm^2^ to ∼10^−8^ A/cm^2^) and increasing R~p~ (200 kΩ cm^2^ to ∼10 MΩ cm^2^). Below 0 mV, the 24 hr R~p~ decreased with negative potential to ∼15 kΩ cm^2^. After 24 hr immersion, oxide dissolution and/or adsorption of organic species caused the capacitance to increase at −1000 mV (AMEM + FBS & PBS) and at −600 mV (AMEM + FBS only). Twenty‐four hours of immersion in AMEM + FBS at −1000 mV and −600 mV produced a surface coloration that is likely due to alteration of oxide valance state and/or doping level. This work shows that Ti surface oxide and its electrochemical behavior can be altered dramatically under sustained cathodic potentials. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010