The localized corrosion of nitinol in blood serum and PBS containing amino acids

The susceptibility to localized corrosion of small implants is typically evaluated in a simulated physiological solution, such as phosphate buffered saline (PBS). For implants in contact with blood, the underlying premise is that proteins and other components in blood do not significantly change the corrosion susceptibility. This study examined the corrosion susceptibility of nitinol in bovine serum and PBS containing amino acids. Tests were performed on mechanically polished (MP) and black oxide nitinol wire using cyclic potentiodynamic polarization and electrochemical impedance spectroscopy. The impedance data were analyzed using equivalent circuit models to evaluate the capacitive and resistive components of the surface oxide with proteins and amino acids present. The cyclic polarization and impedance results were compared with previous results for MP nitinol in PBS to characterize changes in the corrosion behavior.