title: The effect of static applied potential on the 24-hour impedance behavior of commercially pure titanium in simulated biological conditions.
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 (approximately 10(-6) A/cm(2) to approximately 10(-8) A/cm(2)) and increasing R(p) (200 kOmega cm(2) to approximately 10 MOmega cm(2)). Below 0 mV, the 24 hr R(p) decreased with negative potential to approximately 15 kOmega 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.
authors.affiliation: Department of Orthopedic Surgery, State University of New York at Buffalo, Buffalo, New York 14214, USA.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Ehrensberger
authors.forename: Jeremy L
authors.initials: JL
authors.lastname: Gilbert
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D002417:Cattle; D003470:Culture Media; D025802:Electric Capacitance; D017097:Electric Impedance; D004563:Electrochemistry; D066298:In Vitro Techniques; D008422:Materials Testing; D008954:Models, Biological; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D003470:Culture Media; D014025:Titanium