Electrochemical investigation for understanding the bactericidal effect of Cu 2 Se and Ag 2 Se for biomedical applications

Coating systems for titanium implants comprising TiO 2 nanotubes and Se alloys (Cu 2 Se-pTNT and Ag 2 Se-pTNT) were developed in our previous work to prevent bacterial infections at the bone-implant interface. TiO 2 nanotubes were grown on a Ti-based material by anodization and Cu 2 Se or Ag 2 Se alloys were incorporated by pulse electrodeposition. Preliminary in vitro investigations identified promising antibacterial properties. Two possible mechanisms of antibacterial activity are the release of bactericide metal ions and/or the formation of reactive oxygen species (ROS). In this work, the activity of the Se alloys for both effects was investigated by electrochemical measurements. Cu 2 Se and Ag 2 Se alloys were characterized by rotating disk electrode (RDE) measurements to investigate the reaction pathway for the oxygen reduction reaction (ORR) which may lead to peroxide species. RDE measurements, performed at potentials between 0 and − 0.8 V versus Ag/AgCl (sat. KCl) in an isotonic electrolyte (9 g L −1 NaCl, pH 7) at differe n t oxygen partial pressures, showed that both, Cu 2 Se and Ag 2 Se, catalyze the two-electron transfer indicative of an indirect ORR with formation of H 2 O 2 as an intermediate product. For comparison, bare Cu and Ag electrodes were also investigated. Under anodic conditions, selenide alloys slowly release antibacterial metal ions in a controllable and healthy amount for the body. The results demonstrate that these coatings can trigger antibacterial activity by two different mechanisms under both reducing and oxidizing conditions. Graphic abstract