The generation of hydrogen peroxide and antibacterial effectiveness by copper oxide surface layers

抄録

Abstract: Copper is known as an antibacterial material. Reactive oxygen species (ROS) with antibacterial effectiveness are generated on copper surfaces mainly by the Fenton-type reaction. The antibacterial effectiveness is higher in Cu₂O than in CuO. In this study we discussed the effects of the difference in the amount of generated ROS on the difference in the antibacterial effectiveness between Cu₂O and CuO. Both Cu₂O and CuO produced hydrogen peroxide (H₂O₂）, hydroxyl radical(･OH）, and singlet oxygen (¹O₂）, but not superoxide radical (･O₂^-）. The concentration of H₂O₂ produced was higher in Cu₂O than in CuO. When catalase, a scavenger of H₂O₂, was added, the antibacterial activities of both Cu₂O and CuO reduced to almost the same value. These experimental results indicate that Cu₂O is higher in antibacterial effectiveness than CuO because Cu₂O produced more H₂O₂ than CuO. As ･OH was detected even when H₂O₂ was scavenged by catalase before it reacted with Cu ion, a part of ･OH was generated by chemical reactions different from the Fenton-type reaction when copper oxides were in contact with water.