Synthesis, characterization and in vitro antimicrobial prospecting of silver-doped ceria

In this work, Ag-doped CeO2 samples containing 0.5 mol% Ag+ were successfully synthesized by the polymeric precursor method and then calcined at 400, 500, 600 and 700 °C for 2 h. X-ray diffraction and Raman spectra indicated that the crystals have a fluorite-type structure without the presence of other phases. The size of the Ce0.95Ag0.05O1.9−δ crystals increased from 6.61 to 27.46 nm upon increasing the thermal treatment temperature. The decomposition of the samples was examined by differential thermal analysis to determine the most suitable calcination temperature to apply to the materials and indicate the steps involved in obtaining Ag-doped ceria. Scanning electron microscopy images revealed small crystallite sizes, the presence of oxygen vacancies, structural stability and homogeneity. The Ag-doped ceria have shown effective and efficient antimicrobial activity, inhibiting the growth of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa bacteria. However, pure CeO2 displayed no antibacterial activity. Therefore, the satisfactory antimicrobial activity reported here can be attributed to the partial substitution of cerium ions by silver ions.