title: 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.
authors.affiliation: Department of Physics, The University of Hong Kong, Hong Kong.
authors.forename: Y H
authors.initials: YH
authors.lastname: Leung
authors.forename: C M N
authors.initials: CM
authors.lastname: Chan
authors.forename: A M C
authors.initials: AM
authors.lastname: Ng
authors.forename: H T
authors.initials: HT
authors.lastname: Chan
authors.forename: M W L
authors.initials: MW
authors.lastname: Chiang
authors.forename: A B
authors.initials: AB
authors.lastname: Djurišić
authors.forename: Y H
authors.initials: YH
authors.lastname: Ng
authors.forename: W Y
authors.initials: WY
authors.lastname: Jim
authors.forename: M Y
authors.initials: MY
authors.lastname: Guo
authors.forename: F C C
authors.initials: FC
authors.lastname: Leung
authors.forename: W K
authors.initials: WK
authors.lastname: Chan
authors.forename: D T W
authors.initials: DT
authors.lastname: Au
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D001407:Bacillus / Q000187:drug effects; D001424:Bacterial Infections / Q000517:prevention & control; D013293:Enterococcus faecalis / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D006801:Humans; D008029:Lighting; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D017382:Reactive Oxygen Species / Q000378:metabolism; D013499:Surface Properties; D015034:Zinc Oxide / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D017382:Reactive Oxygen Species; D015034:Zinc Oxide