2022 年 33 巻 4 号 p. 112-117
A layered silicate, KHSi2O5, was synthesized via a hydrothermal method using an amorphous silicon dioxide (SiO2) block, which is industrial waste. This layered silicate was used as a host compound for ion-exchange reactions with Ag+ and Cu2+ ions, and the antibacterial properties of the ion-exchanged compounds were investigated. The crystal structures of the compounds were retained during the ion-exchange reaction; however, in the case of Cu2+, a small amount of Cu(OH)2 coexisted. The M/Si (where M is Ag or Cu) ratios of the ion-exchanged compounds were 0.03 - 0.50 and 0.01 - 0.32 for M = Ag and Cu, respectively. The antibacterial activity was analyzed by the inhibition zone method using two standard model bacteria: Staphylococcus aureus (S. aureus,gram-positive) and Escherichia coli (E. coli, gram-negative). The Ag-KHSi2O5 and Cu-KHSi2O5 samples showed good antibacterial activity owing to the release of Ag+ and Cu2+ ions from their host silicates. Here, the antibacterial activity of each sample were compared by relative antibacterial activity which was calculated based on the bacterial inhibition zone area. The antibacterial activity of Ag-KHSi2O5 against S. aureus was higher than that against E. coli, whereas the antibacterial activity of Cu-KHSi2O5 against S. aureus was lower than that against E. coli.
