title: Morphology-dependent bactericidal activities of Ag/CeO2 catalysts against Escherichia coli.
abstract: Silver-loaded CeO2 nanomaterials (Ag/CeO2) including Ag/CeO2 nanorods, nanocubes, nanoparticles were prepared with hydrothermal and impregnation methods. Catalytic inactivation of Escherichia coli with Ag/CeO2 catalysts through the formation of reactive oxygen species (ROS) was investigated. For comparison purposes, the bactericidal activities of CeO2 nanorods, nanocubes and nanoparticles were also studied. There was a 3-4 log order improvement in the inactivation of E. coli with Ag/CeO2 catalysts compared with CeO2 catalysts. Temperature-programmed reduction of H2 showed that Ag/CeO2 catalysts had higher catalytic oxidation ability than CeO2 catalysts, which was the reason for that Ag/CeO2 catalysts exhibited stronger bactericidal activities than CeO2 catalysts. Further, the bactericidal activities of CeO2 and Ag/CeO2 depend on their shapes. Results of 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping measurements by electron spin resonance and addition of catalase as a scavenger indicated the formation of OH, O2(-), and H2O2, which caused the obvious bactericidal activity of catalysts. The stronger chemical bond between Ag and CeO2 nanorods led to lower Ag(+) elution concentrations. The toxicity of Ag(+) eluted from the catalysts did not play an important role during the bactericidal process. Experimental results also indicated that Ag/CeO2 induced the production of intracellular ROS and disruption of the cell wall and cell membrane. A possible production mechanism of ROS and bactericidal mechanism of catalytic oxidation were proposed.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Lian
authors.initials: L
authors.lastname: Wang
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: honghe@rcees.ac.cn.
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Yunbo
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Li
authors.initials: L
authors.lastname: Sun
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Sijin
authors.initials: S
authors.lastname: Liu
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Changbin
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Lian
authors.initials: L
authors.lastname: He
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D002384:Catalysis; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D002473:Cell Wall / Q000187:drug effects / Q000648:ultrastructure; D002563:Cerium / Q000737:chemistry* / Q000494:pharmacology; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D053758:Nanoparticles / Q000737:chemistry; D010087:Oxides / Q000737:chemistry* / Q000494:pharmacology; D010316:Particle Size; D017382:Reactive Oxygen Species / Q000378:metabolism; D018030:Silver Compounds / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D010087:Oxides; D017382:Reactive Oxygen Species; D018030:Silver Compounds; D002563:Cerium; C030583:ceric oxide; C040225:disilver oxide
keywords: Bactericidal activity; CeO(2); E. coli; ROS; Silver