氧化鈰奈米尺寸微粒本質是觸媒，由於高比表面積氧化鈰具有大量氧缺陷，表面鈰離子能捕獲或釋出氧，易進行Ce3+/4+的轉換，因此催化許多鄰近環境中的有機分子氧化還原反應，而具有細胞毒性。利用簡易、低廉的共沉澱法合成氧化鈰，及摻雜(doping) 10 mol % 銀來增加抑菌效果，尺寸約9-10 nm。由XRD、SEM、EDX、Raman進行二氧化鈰奈米粒子的材料特性分析，分析結果顯示共沉澱合成法確實讓金屬離子摻雜進到二氧化鈰晶格裡。
本研究所採用的菌種最常見的革蘭氏陰性菌(Gram-negative)-大腸桿菌(Escherichia coli)及革蘭氏陽性菌(Gram-positive)-金黃葡萄球菌亞種(Staphylococcus aureus subsp. aureus)，以比濁法(turbidimetry)在液態培養液量測菌液的吸光度(optical density, OD)得知細菌生長情形
，並利用平板計數法(plate count method)定量細菌在固態培養基存活的菌落數(CFU/mL)，了解奈米粒子對細菌的抑制能力表現。另外透過倒立式螢光顯微鏡，以PI試劑和DCFH-DA試劑染色細菌，觀察細菌與奈米粒子作用的情形。實驗結果顯現二氧化鈰對於金黃葡萄球菌亞種的抑制能力優於大腸桿菌，不同的是，摻雜銀的二氧化鈰對於大腸桿菌比金黃葡萄球菌亞種有優異的抑制效果，甚至有殺菌的效果，其分別對大腸桿菌和金黃葡萄球菌亞種的最低殺菌濃度(minimal bactericidal concentration, MBC)為0.375 mg/mL和1.5 mg/mL，因此二氧化鈰可以說是有效的銀載體。由此可推測，摻雜銀離子有效提升二氧化鈰的抑菌能力，摻雜銀氧化鈰奈米粒子優異殺菌能力來自二氧化鈰與銀兩者的相乘效果(synergetic effect)。

Ceria particles of nanometer size are catalysts owing to their high surface area loaded with a high fraction of oxygen defects. The surface cerium ion is capable of capturing or releasing oxygen, which facilitates the conversion between Ce3+ and Ce4+ and catalyzes many redox reactions of organic molecules in its neighborhood. Such a catalytic property makes ceria nanoparticles cytotoxic toward microorganism. We apply the facile precipitation method to synthesize ceria nanoparticle of 9-10 nm in size, further characterize these inexpensive ceria nanoparticles, and confirm the disinfection functions of undoped and silver-doped particles. The two compositions have shown market potential.
We analyze the cytotoxicity of ceria nanoparticles using the turbidimetric method and the plate count method of microbiology. Among the undoped ceria, and 10 mol% silver, copper, chromium, aluminum doped ceria samples, the silver doped sample stands out as the most disinfecting agent, with the sterilization effect far exceeding other four samples. The sterilization effects of samples doped with copper and chromium are similar to that of the undoped ceria, while the aluminum doped sample shows an inferior sterilization capability. Further analysis on the disinfection mechanism indicates that the sterilization effect of ceria originates from its contact with the cell wall of bacteria and the reactive oxygen species generated on ceria surface damage the cell wall, resulting in the cell killing. Thus, dispersion of the ceria nanoparticle has tremendous influences on its sterilization effect. On the other hand, the silver doped sample releases disinfecting silver ions, in addition to the above sterilization effect. Since the silver doped ceria powder is an excellent silver carrier, we attribute its disinfecting ability to the synergetic effect of the two mechanisms.

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