This paper reports the preparation of copper(I) oxide nanoparticles deposited on yttrium oxide and copper(II) oxide in the presence of acerola and white willow extracts. Through the use of natural compounds, it was possible to modify the surface of the Y₂O₃ and CuO carriers allowing Cu₂O to be deposited to a greater extent, thus improving the antibacterial properties of the materials. Cu₂O nanoparticles, by being deposited on a carrier, enable an increase in the contact surface of the nanoparticles with microorganisms, which react to form reactive oxygen species. Cu₂O nanoparticles with sizes of about 38 nm and 76 nm were obtained for Y₂O₃- and CuO-deposited nanoparticles, respectively. The Gram-negative bacteria Escherichia coli shown a greater sensitivity to the degree of inhibition compared to Staphylococcus Aureus already at a concentration of 250 mg/L. For almost all materials, the inhibition level remained above 50% after 48 h. Analysis of the effect of the antimicrobial properties of the materials against Candida albicans fungus shown high activity which was obtained only at the highest concentrations of 8000 mg/L, for which the degree of growth inhibition was 100% also after 48 h for both Y₂O₃–Cu₂O and CuO–Cu₂O.