Comparative study of the antifungal activity of cations of Ce, La, Ag and their nanocomposites [in English]

In this study, a comparative analysis of the antifungal activity of cations of cerium, lanthanum and silver, as well as nanosized oxides and silver-containing composites based on rare earth elements (REE), was performed. The oxides were synthesized by chemical precipitation followed by thermal treatment at 400-600 °C and characterized using X‑ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy and electrokinetic methods. Cerium dioxide formed a fluorite-type crystal structure, while lanthanum oxide crystallized in a hexagonal system. Silver formed metallic clusters on oxide surfaces due to Ce+ / Ce4+ oxidation and Ag+ / Ag0 reduction processes. Antifungal activity was evaluated against Aspergillus niger, Candida albicans, Cyberlindnera jadinii, Mrakia aquatica, and Penicillium polonicum using the agar diffusion method. Silver nitrate solutions showed the strongest inhibitory effect against all tested fungi. Unmodified oxides demonstrated limited activity, inhibiting only P. polonicum. In contrast, silver-modified oxides exhibited enhanced antifungal activity against most tested strains. Overall, silver cations and containing them nanocomposites showed larger inhibition zones compared to the antibiotic control, indicating their high potential as antifungal agents.