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

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.

Synthesis and comparative studies of MnFe2O4 nanoparticles with different natural polymers by sol–gel method: structural, morphological, optical, magnetic, catalytic and biological activities

“…Due to this, NPs grab attention in the clinical application to produce a variety of new bactericidal agent [2,3]. The materials in nanoscale can penetrate into bacterial cells and produce toxic oxygen radicals to damage cell membranes of microbes that produce an efficient inhibition bacterial growth [4][5][6][7]. Spinel structure ferrite nanoparticles creates a great impact among the science researchers because of its wide applications in magnetic resonance imaging, magnetic storage devices, biotechnology, electronics, magnetic drug delivery [8][9][10], etc.…”

Damage of lipopolysaccharides in outer cell membrane and production of ROS-mediated stress within bacteria makes nano zinc oxide a bactericidal agent

“…There have been a lot of speculations about the mode of action of ZNP as an antibacterial agent. Considerable antibacterial activity of ZNP is attributed to the generation of reactive oxygen species (ROS) on the surface of these oxides (Applerot et al 2009;Augustine et al 2014a, b;Maschhoff et al 2014). Although there is no ambiguity over the formation of ROS and it can be considered that ROS does the fatal damage to the bacterial system, how the as formed ROS reaches the bacterial cell to execute the lethal response is yet to resolve.…”

Fe3+-saturated montmorillonite effectively deactivates bacteria in wastewater

“…Those nanomaterials include silver nanoparticles (Dankovich and Gray, 2011;Morones et al, 2005;Panáček et al, 2006), copper and copper oxide nanoparticles (Ben-Sasson et al, 2013;Meghana et al, 2015), titanium dioxide Simon-Deckers et al, 2009), carbon nanotubes (Tiraferri et al, 2011;Vecitis et al, 2010), zinc oxide (Applerot et al, 2009;Raghupathi et al, 2011), fullerenes (Lyon and Alvarez, 2008) and graphene materials Liu et al, 2012;Perreault et al, 2015;Wu et al, 2013). Among them, silverbased nanomaterials have been most widely explored owing to their antibacterial properties to a broad spectrum of microorganisms (Panáček et al, 2006).…”