Preparation and Antiviral Activity of La ₂ CuO ₄ and Y ₂ Cu ₂ O ₅ with Mechanistic Insights from First-Principles

High Resolution Image Download MS PowerPoint Slide Copper oxide is a representative inorganic antiviral material. However, the highly active Cu 2 O phase transforms gradually into CuO, which results in reduced antiviral activity. For this study, we aimed at developing a material with high antiviral activity based on CuO. To this end, La 2 CuO 4 and Y 2 Cu 2 O 5 were synthesized respectively by combining CuO with La 2 O 3 and Y 2 O 3 . Their antiviral properties were investigated. For comparison, Al 2 CuO 4 and the simple oxides of each constituent element were also prepared and evaluated. The ternary oxides synthesized using citric acid combustion method and the solid-state reaction method were confirmed to be single-phase. Surface analysis revealed the presence of Cu + on La 2 CuO 4 and Y 2 Cu 2 O 5 . The amount of ion release from these materials was found to be low. Antiviral activity tests were conducted against the nonenveloped bacteriophage Qβ and the enveloped bacteriophage Φ6, following ISO-standard evaluation methods. La 2 CuO 4 and Y 2 Cu 2 O 5 exhibited stronger antiviral activity against Qβ than either CuO, La 2 O 3, or Y 2 O 3 . Detailed analyses suggested that the enhanced activity was attributable to strengthened electrostatic interactions and an improved ability to inactivate proteins. In contrast, La 2 O 3 and Y 2 O 3 showed relatively high antiviral activity against Φ6, primarily because of their strong affinity for phosphate groups. First-principles calculations indicate that (i) the surfaces of these ternary oxides containing Cu 2+ are cation-rich and (ii) the surface formal charge of copper is predominantly monovalent. These findings suggest that the unique surface states because of their crystal structures play a crucially important role in the antiviral performance of La 2 CuO 4 and Y 2 Cu 2 O 5 . The antiviral activity of La 2 CuO 4 against Qβ exhibited high long-term stability, surpassing the reported performance of Cu 2 O. The present study is expected to provide promising new materials with improved antiviral activities compared to conventional CuO.