Summary: | Photocatalysts have recently attracted attention for removing infectious-disease-causing bacteria and viruses. Among such photocatalysts, ground Rh-doped SrTiO<sub>3</sub> (“g-STO:Rh”) has been found to have biospecificity that reduces the Qβ phage infectivity under conditions that did not decrease the <i>E. coli</i> survival rate. Elucidating the mechanism of selective antiphage activation is important for developing photocatalysts that act effectively against specific microorganisms. In this study, SDS-PAGE and quantitative PCR showed that a g-STO:Rh-treated Qβ phage preferentially inactivated the A2 protein involved in attachment to host cells. The analysis of the photocatalyst-treated ovalbumin using g-STO:Rh indicated that the protein’s isoelectric point significantly influenced the initial interaction with g-STO:Rh. However, once the protein is absorbed, it was decomposed without the release of intermediates. Furthermore, an inactivation assay for four different phages by photocatalyst treatment using g-STO:Rh revealed that phages with positively charged proteins are highly susceptible to inactivation, and the accessibility of critical components to g-STO:Rh influences susceptibility. We conclude that the selective antiphage activation of g-STO:Rh depends on the adsorption efficiency of the protein and g-STO:Rh.
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