Electrochemical and antimicrobial properties of diamondlike carbon-metal composite films

Implants containing antimicrobial metals may reduce morbidity, mortality, and healthcare costs associated with medical device-related infections. We have deposited diamondlike carbon–silver (DLC–Ag), diamondlike carbon–platinum (DLC–Pt), and diamondlike carbon–silver–platinum (DLC–AgPt) thin films using a multicomponent target pulsed laser deposition process. Transmission electron microscopy of the DLC–silver and DLC–platinum composite films revealed that the silver and platinum self-assemble into nanoparticle arrays within the diamondlike carbon matrix. The diamondlike carbon–silver film possessed hardness and Young’s modulus values of 37 GPa and 331 GPa, respectively. The diamondlike carbon-metal composite films exhibited passive behavior at open-circuit potentials. Low corrosion rates were observed during testing in a phosphate-buffered saline (PBS) electrolyte. In addition, the diamondlike carbon–metal composite films were found to be immune to localized corrosion below 1000 mV (SCE). DLC–silver–platinum films demonstrated exceptional antimicrobial properties against Staphylococcus bacteria. It is believed that a galvanic couple forms between platinum and silver, which accelerates silver ion release and provides more robust antimicrobial activity. Diamondlike carbon–silver–platinum films may provide unique biological functionalities and improved lifetimes for cardiovascular, orthopaedic, biosensor, and implantable microelectromechanical systems.