Complex electrochemical studies on silver-coated metallic implants for orthopaedic application

Abstract

Silver grains were deposited by pulse current technique onto different implant materials—Ti6Al4V and CoCrMo alloys—that are commonly used in orthopaedic surgery. The electrochemical behaviour of the coatings and the silver ion release rate were investigated by polarization potentiodynamic and electrochemical impedance spectroscopy (EIS) methods over a period of several weeks in isotonic salt solution. For antimicrobial applications, it is very important to maintain a continuous and long-term release of silver ions. The corrosion properties of silver-coated different implant materials and the silver dissolution rate were compared. The open circuit potentials shifted to more positive values for both uncoated and coated substrate materials in 0.9 % sodium chloride solution. The silver modified implants possess more negative corrosion potentials than that of pure implants. The potentiodynamic curves revealed that the silver-modified implant materials have higher anodic and cathodic current densities compared to bare implant by almost one order of magnitude. The values of charge transfer resistance decreased in approximately 10 days for all silver-coated samples but after that, slightly changed due to the layer passivation. The morphology of the coatings was studied by scanning electron microscopy (SEM) micrographs and energy dispersive spectroscopy (EDX) measurements. To determine the silver ion concentration released from the silver-modified implant materials into physiological solution during different time of immersion, inductively coupled plasma mass spectroscopy (ICP-MS) method was used.