Antibacterial activity of ZnO nanoparticles with a modified surface under ambient illumination

Abstract

In various practical applications, nanomaterials typically have functionalized surfaces. Yet, the studies of toxicity and antibacterial activity of functionalized nanoparticles are scarce. We investigated the effect of surface modifications on antibacterial activity of ZnO under ambient illumination, and we found that nanoparticles coated with different surface modifying reagents could exhibit higher or lower toxicity compared to bare ZnO, depending on the surface modifying reagent used. Different surface modifying reagent molecules resulted in differences in the release of Zn(2+) ions and the production of reactive oxygen species (ROS). However, the antibacterial activity did not correlate with the ROS levels or the Zn(2+) ion release. One of the surface-modified ZnO samples exhibited significantly lower Zn(2+) ion release while at the same time exhibiting improved antibacterial activity. In all cases, damage of the cell wall membranes and/or changes in the membrane permeability have been observed, together with the changes in ATR-FTIR spectra indicating differences in protein conformation. Mechanisms of antibacterial activity are discussed.

Toxicity of CeO2 nanoparticles – The effect of nanoparticle properties

“…11. All samples exhibit absorption peaks at $3420 cm À1 and 1626 cm À1 attributed to the vibration modes of OH groups and scissoring mode of molecular water, respectively [54][55][56][57]. The small peaks at 2924 cm À1 and 2855 cm À1 correspond to C-H bond from organic materials adsorbed on the surface.…”

“…This possibly indicates lower presence of adsorbed OH groups in this sample, which could affect its toxicity. For 1-CeO 2 and HT-CeO 2 there are absorption peaks near 1560 cm À1 and 1384 cm À1 which arise from the antisymmetric stretching band of carboxyl group and absorption of CO 2 on the metallic cations, respectively [54,57]. The more numerous and pronounced peaks associated with organic molecules on 1-CeO 2 and HT-CeO 2 indicate either the presence of adsorbed surfactant molecules or the unintentional residues introduced from the synthesis procedure.…”

Role of fatty acid composites in the toxicity of titanium dioxide nanoparticles used in cosmetic products

“…Abd Gani et al (2014) showed that coating TiO 2 particles with fatty acids commonly used in cosmetics can increase UV absorption, but have not demonstrated the efficacy of "nanosized" particles. Leung et al (2012) observed that the antibacterial activity is enhanced as a result of surface modification of zinc oxide NPs. However, neither study examined the effect of surface modification of NPs in cell toxicity.…”

Role of physical and chemical interactions in the antibacterial behavior of ZnO nanoparticles against E. coli

“…The generation of ROS has been known to contribute to ZnO NPs antibacterial activity [31]. In this study, radical scavengers (Mannitol, Vitamin E and Glutathione (GSH)) were employed to indirectly assess whether radical formation was responsible, , because they can alter the kinetic profile of the reaction.…”