Electrochemical Analysis of the Redox State of Silver Contained in Antibacterial Material

Introduction of silver into some inorganic material causes the resulting mixture to have antibacterial activity. Here, we investigated the role of silver in the bactericidal activity of silver-loaded zeolite, by measuring the effects of silverloaded zeolite on Escherichia coli cell viability under conditions in which the oxidation state of the silver was controlled electrochemically. Bactericidal activity was observed when the sweeping voltage between 0 and 0.7 V was applied to the silver electrode. When nitrogen gas bubbling or reactive oxygen scavengers were added to the experimental system, bactericidal activity decreased. These results indicated that the redox cycle, Ag <—> Ag, caused the dissolved oxygen to form reactive oxygen species.