Antimicrobial activity of silver loaded MnO₂ nanomaterials with different crystal phases against Escherichia coli

详细信息    查看全文

• 作者：Lian Wang ; Hong He ; ^{honghe@rcees.ac.cn" class="auth_mail" title="E-mail the corresponding author} ; Changbin Zhang ; Li Sun ; Sijin Liu ; Shaoxin Wang
• 关键词：Silver ; MnO2 ; Bactericidal activity ; Escherichia coli ; ROS
• 刊名：Journal of Environmental Sciences
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：41
• 期：Complete
• 页码：112-120
• 全文大小：907 K

文摘

Silver-loaded MnO₂ nanomaterials (Ag/MnO₂), including Ag/α-MnO₂, Ag/β-MnO₂, Ag/γ-MnO₂ and Ag/δ-MnO₂ nanorods, were prepared with hydrothermal and impregnation methods. The bactericidal activities of four types of Ag/MnO₂ nanomaterials against Escherichia coli were investigated and an inactivation mechanism involving Ag⁺ and reactive oxygen species (ROS) was also proposed. The bactericidal activities of Ag/MnO₂ depended on the MnO₂ crystal phase. Among these nanomaterials, Ag/β-MnO₂ showed the highest bactericidal activity. There was a 6-log decrease in E. coli survival number after treatment with Ag/β-MnO₂ for 120 min. The results of 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping measurements by electron spin resonance indicate OH and O₂‾ formation with addition of Ag/β-MnO₂, Ag/γ-MnO₂ or Ag/δ-MnO₂. The strongest peak of OH appeared for Ag/β-MnO₂, while no OH or O₂‾ signal was found over Ag/α-MnO₂. Through analysis of electron spin resonance (ESR) and Ag⁺ elution results, it could be deduced that the toxicity of Ag⁺ eluted from Ag/MnO₂ nanomaterials and ROS played the main roles during the bactericidal process. Silver showed the highest dispersion on the surface of β-MnO₂, which promoted ROS formation and the increase of bactericidal activity. Experimental results also indicated that Ag/MnO₂ induced the production of intracellular ROS and disruption of the cell wall and cell membrane.