Electrochemical and SEM characterization of gold-coated stents in vitro

The inert properties of gold make it a useful material for implants. Gold was applied as a coating on 316L stainless steel stents to improve the radiopacity and to provide better thrombogenic resistance and a lower degree of restenosis after deployment. Reports of clinical trials using gold-coated stents showed controversial results. A detailed examination of gold-coated stents was designed to understand the influence of surface conditions on the electrochemical properties in vitro. Corrosion resistance of gold-coated stents was investigated by cyclic polarization, and potentiostatic control. Surface morphologies of gold-coated stents in as-received condition, postinflated condition, and after cyclic polarization were characterized by scanning electron spectroscopy (SES). X-ray mapping identified elemental distribution. Results found severe defects in the gold-coating in the as-received condition, cracks and wrinkles on inflated gold-coated stents, and severe corrosion after cyclic polarization. Leaching of metallic ions in Ringer's solution was possible.