Visible-light-induced modulation of antiviral activity in La-doped Bi₂MoO₆

Abstract

In this study, Bi₂MoO₆ and La-doped Bi_1.8La_0.2MoO₆ (10 % substitution at the Bi site) powders were synthesized via a coprecipitation method, and their antiviral activities were evaluated against two structurally distinct viruses—an enveloped virus (Φ6) and a non-enveloped virus (Qβ)—using a method based on ISO standards. The obtained samples were pale-yellow, single-phase powders with nearly identical specific surface areas and band gaps. Bi₂MoO₆ showed negligible antiviral activity under both dark and visible-light conditions. In contrast, Bi_1.8La_0.2MoO₆ exhibited antiviral activity against both Qβ and Φ6 under dark conditions. Under visible-light irradiation, the activity against Qβ increased compared to that in the dark, whereas the activity against Φ6 decreased. Mechanistic analysis suggests that antiviral activity against Qβ in the dark arises from La-induced capsid disruption, whereas activity against Φ6 is associated with degradation and perforation of the viral envelope by leached ions. Although no photocatalytic activity was observed under visible light in 2-naphthol tests, electron excitation was confirmed. These results indicate that charge redistribution, local potential modulation, and charge transfer induced by electron excitation may govern the differences in antiviral activity between dark and visible-light conditions. This material exhibits light-dependent antiviral selectivity toward different virus types.