title: Trace amounts of Cu²⁺ ions influence ROS production and cytotoxicity of ZnO quantum dots.
abstract: 3-Aminopropyltrimethoxysilane (APTMS) was used as ligand to prepare ZnO@APTMS, Cu(2+)-doped ZnO (ZnO:Cu@APTMS) and ZnO quantum dots (QDs) with chemisorbed Cu(2+) ions at their surface (ZnO@APTMS/Cu). The dots have a diameter of ca. 5 nm and their crystalline and phase purities and composition were established by X-ray diffraction, transmission electron microscopy, UV-visible and fluorescence spectroscopies and by X-ray photoelectron spectroscopy. The effect of Cu(2+) location on the ability of the QDs to generate reactive oxygen species (ROS) under light irradiation was investigated. Results obtained demonstrate that all dots are able to produce ROS (OH, O2(-), H2O2 and (1)O2) and that ZnO@APTMS/Cu QDs generate more OH and O2(-) radicals and H2O2 than ZnO@APTMS and ZnO:Cu@APTMS QDs probably via mechanisms associating photo-induced charge carriers and Fenton reactions. In cytotoxicity experiments conducted in the dark or under light exposure, ZnO@APTMS/Cu QDs appeared slightly more deleterious to Escherichia coli cells than the two other QDs, therefore pointing out the importance of the presence of Cu(2+) ions at the periphery of the nanocrystals. On the other hand, with the lack of photo-induced toxicity, it can be inferred that ROS production cannot explain the cytotoxicity associated to the QDs. Our study demonstrates that both the production of ROS from ZnO QDs and their toxicity may be enhanced by chemisorbed Cu(2+) ions, which could be useful for medical or photocatalytic applications.
authors.affiliation: CNRS and Université de Lorraine, Laboratoire Réactions et Génie des Procédés (LRGP), CNRS UMR 7274, 1 rue Grandville, 54001 Nancy, France; Laboratoire de Biosurveillance de l'Environnement, Université de Carthage, Faculté des Sciences de Bizerte, 7021 Jarzouna, Bizerte, Tunisia.
authors.forename: Hatem
authors.initials: H
authors.lastname: Moussa
authors.affiliation: CNRS and Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), CNRS UMR 7564, 15 Avenue du Charmois, 54500 Vandœuvre-lès-Nancy, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Merlin
authors.affiliation: CNRS and Université de Lorraine, Laboratoire Réactions et Génie des Procédés (LRGP), CNRS UMR 7274, 1 rue Grandville, 54001 Nancy, France.
authors.forename: Clément
authors.initials: C
authors.lastname: Dezanet
authors.affiliation: Institut de Science des Matériaux de Mulhouse (IS2M), CNRS UMR 7361, 15 rue Jean Starcky, 68093 Mulhouse, France.
authors.forename: Lavinia
authors.initials: L
authors.lastname: Balan
authors.affiliation: CNRS and Université de Lorraine, Institut Jean Lamour (IJL), UMR CNRS 7198, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, France.
authors.forename: Ghouti
authors.initials: G
authors.lastname: Medjahdi
authors.affiliation: Laboratoire de Biosurveillance de l'Environnement, Université de Carthage, Faculté des Sciences de Bizerte, 7021 Jarzouna, Bizerte, Tunisia.
authors.forename: Mossadok
authors.initials: M
authors.lastname: Ben-Attia
authors.affiliation: CNRS and Université de Lorraine, Laboratoire Réactions et Génie des Procédés (LRGP), CNRS UMR 7274, 1 rue Grandville, 54001 Nancy, France. Electronic address: raphael.schneider@univ-lorraine.fr.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Schneider
mesh_terms: D003300:Copper / Q000737:chemistry / Q000633:toxicity; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D011437:Propylamines / Q000737:chemistry / Q000633:toxicity; D045663:Quantum Dots / Q000737:chemistry / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000633:toxicity; D012821:Silanes / Q000737:chemistry / Q000633:toxicity; D015034:Zinc Oxide / Q000737:chemistry / Q000633:toxicity
chemical_list: D011437:Propylamines; D017382:Reactive Oxygen Species; D012821:Silanes; C088294:3-aminopropyltrimethoxysilane; D003300:Copper; D015034:Zinc Oxide
keywords: Copper; E. coli; Reactive oxygen species; Toxicity; Zinc oxide quantum dots