Titanium dioxide nanoparticles induce bacterial membrane rupture by reactive oxygen species generation

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• 作者：Shivendu Ranjan ; Chidambaram Ramalingam
• 关键词：Titanium dioxide nanoparticle ; Microwave ; irradiation ; assisted hybrid chemical approach ; Antimicrobial ; Mechanism of action ; Foods and Drugs ; Ecotoxicology
• 刊名：Environmental Chemistry Letters
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：14
• 期：4
• 页码：487-494
• 全文大小：849 KB
• 刊物类别：Earth and Environmental Science
• 刊物主题：Earth sciences
  Geochemistry
  Analytical Chemistry
  Biochemistry
  Monitoring, Environmental Analysis and Environmental Ecotoxicology
  Soil Science and Conservation
  Waste Water Technology, Water Pollution Control, Water Management and Aquatic Pollution
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1610-3661
• 卷排序：14

文摘

Nano-titania is widely used in the food industry due to its efficient antimicrobial activity. However, the mechanism of microbial toxicity of nano-titania is poorly known. Here, nano-TiO₂ has been fabricated by microwave-irradiation chemistry, a new method, and then tested for antimicrobial activity. Mutagenicity of nano-TiO₂ was evaluated using Salmonella typhimurium histidine-auxotrophic strains. The reactive oxygen generation test was performed using 2,7-dichlorofluorescein diacetate dye. To test membrane permeabilization, E. coli cultures were grown in nutrient broth at an optical density of 0.3–0.5 at 610 nm, harvested by centrifugation at 11,000g for 10 min, washed and resuspended in 0.5 % NaCl solution. We also analyzed superoxide formation and membrane integrity, and we used scanning electron microscopy. Results show that nano-TiO₂ has a minimum inhibitory concentration of 15 µg/mL, and a minimum bactericidal concentration of 20 µg/mL for E. coli. The bacterial inner wall was ruptured, and cytoplasmic content was released after 5 min of treatment in a dose-dependent manner. Notably, superoxide formation was not observed, which establishes the fact that reactive oxygen generation and alteration of membrane integrity, as well as permeability, is the major mechanism of antimicrobial activity of nano-TiO₂.