Antimicrobial and antiviral activity of proton-type zirconium phosphate

Abstract

Antibacterial and antiviral inorganic materials are attracting increasing attention for their biomedical and environmental applications. This study aimed to examine the antibacterial and antiviral properties of zirconium phosphate powders, Zr(HPO₄)₂·H₂O, Zr(PO₄)(H₂PO₄)·2H₂O, HZr₂(PO₄)₃, and (H₃O)Zr₂(PO₄)₃, and to clarify the role of pH in their activity. Antibacterial activity against Escherichia coli was confirmed in Zr(PO₄)(H₂PO₄)·2H₂O, HZr₂(PO₄)₃, and (H₃O)Zr₂(PO₄)₃ powders; high antiviral activity against the bacteriophage Qβ was detected in Zr(PO₄)(H₂PO₄)·2H₂O and (H₃O)Zr₂(PO₄)₃ powders, with the antiviral activity of Zr(PO₄)(H₂PO₄)·2H₂O being superior to that of (H₃O)Zr₂(PO₄)₃. After immersion in deionized water for 1 d, the pH values of the Zr(PO₄)(H₂PO₄)·2H₂O, HZr₂(PO₄)₃, and (H₃O)Zr₂(PO₄)₃ powders reduced to 3.64, 4.41, and 3.99, respectively, becoming lower than that of Zr(HPO₄)₂·H₂O (5.12). The observed effects were attributed to the lower pH caused by the formation of H₃O⁺ upon contact with water. These results demonstrate that acidity is crucial in the antibacterial and antiviral functions of zirconium phosphate-based materials, providing insights for the design of functional inorganic antimicrobial agents.