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Enhanced Antibacterial Activity of Nanocrystalline ZnO Due to Increased ROS-Mediated Cell Injury

Authors

  • Guy Applerot,

    1. Department of Chemistry and Kanbar Laboratory for Nanomaterials Bar-Ilan University Center for Advanced Materials and Nanotechnology Bar-Ilan University Ramat-Gan 52900 (Israel)
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  • Anat Lipovsky,

    1. Department of Chemistry and Kanbar Laboratory for Nanomaterials Bar-Ilan University Center for Advanced Materials and Nanotechnology Bar-Ilan University Ramat-Gan 52900 (Israel)
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  • Rachel Dror,

    1. The Mina & Everard Goodman Faculty of Life Sciences Bar-Ilan University Ramat-Gan 52900 (Israel)
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  • Nina Perkas,

    1. Department of Chemistry and Kanbar Laboratory for Nanomaterials Bar-Ilan University Center for Advanced Materials and Nanotechnology Bar-Ilan University Ramat-Gan 52900 (Israel)
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  • Yeshayahu Nitzan,

    1. The Mina & Everard Goodman Faculty of Life Sciences Bar-Ilan University Ramat-Gan 52900 (Israel)
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  • Rachel Lubart,

    1. Department of Chemistry and Kanbar Laboratory for Nanomaterials Bar-Ilan University Center for Advanced Materials and Nanotechnology Bar-Ilan University Ramat-Gan 52900 (Israel)
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  • Aharon Gedanken

    Corresponding author
    1. Department of Chemistry and Kanbar Laboratory for Nanomaterials Bar-Ilan University Center for Advanced Materials and Nanotechnology Bar-Ilan University Ramat-Gan 52900 (Israel)
    • Department of Chemistry and Kanbar Laboratory for Nanomaterials Bar-Ilan University Center for Advanced Materials and Nanotechnology Bar-Ilan University Ramat-Gan 52900 (Israel).
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Abstract

An innovative study aimed at understanding the influence of the particle size of ZnO (from the microscale down to the nanoscale) on its antibacterial effect is reported herein. The antibacterial activity of ZnO has been found to be due to a reaction of the ZnO surface with water. Electron-spin resonance measurements reveal that aqueous suspensions of small nanoparticles of ZnO produce increased levels of reactive oxygen species, namely hydroxyl radicals. Interestingly, a remarkable enhancement of the oxidative stress, beyond the level yielded by the ZnO itself, is detected following the antibacterial treatment. Likewise, an exposure of bacteria to the small ZnO nanoparticles results in an increased cellular internalization of the nanoparticles and bacterial cell damage. An examination of the antibacterial effect is performed on two bacterial species: Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive). The nanocrystalline particles of ZnO are synthesized using ultrasonic irradiation, and the particle sizes are controlled using different solvents during the sonication process. Taken as a whole, it is apparent that the unique properties (i.e., small size and corresponding large specific surface area) of small nanometer-scale ZnO particles impose several effects that govern its antibacterial action. These effects are size dependent and do not exist in the range of microscale particles.

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