title: Physicochemical properties and cellular toxicity of (poly)aminoalkoxysilanes-functionalized ZnO quantum dots.
abstract: Luminescent ZnO nanocrystals were synthesized by basic hydrolysis of Zn(OAc)(2) in the presence of oleic acid and then functionalized with (poly)aminotrimethoxysilanes in the presence of tetramethylammonium hydroxide to render the QDs water-dispersible. The highest photoluminescence quantum yield (17%) was achieved using N(1)-(2-aminoethyl)-N(2)-[3-(trimethoxysilyl)propyl]-1,2-ethanediamine as surface ligand. Transmission electron microscopy and powder x-ray diffraction showed highly crystalline materials with a ZnO nanoparticle diameter of about 4 nm. The cytotoxicity of the different siloxane-capped ZnO QDs towards growing  Escherichia coli bacterial cells was evaluated in MOPS-minimal medium. Although concentrations of 5 mM in QDs caused a complete growth arrest in  E. coli, siloxane-capped ZnO QDs appeared weakly toxic at lower doses (0.5 or 1 mM). The concentration of bioavailable Zn (2+) ions leaked from ZnO QDs was evaluated using the biosensor bacteria  Cupriavidus metallidurans AE1433. The results obtained clearly demonstrate that concentrations of bioavailable Zn(2+) are too low to explain the inhibitory effects of the ZnO QDs against bacteria cells at 1 mM and that the siloxane shell prevents ZnO QDs from dissolution contrary to uncapped ZnO nanoparticles. Because of their low cytotoxicity, good biocompatibility, low cost and large number of functional amine end groups, which makes them easy to tailor for end-user purposes, siloxane-capped ZnO QDs offer a high potential as fluorescent probes and as biosensors.
authors.affiliation: Laboratoire Réactions et Génie des Procédés, UPR 3349, CNRS-Université de Lorraine, 1 rue Grandville, F-54001 Nancy Cedex, France.
authors.forename: Abdelhay
authors.initials: A
authors.lastname: Aboulaich
authors.forename: Carmen-Mihaela
authors.initials: CM
authors.lastname: Tilmaciu
authors.forename: Christophe
authors.initials: C
authors.lastname: Merlin
authors.forename: Cédric
authors.initials: C
authors.lastname: Mercier
authors.forename: Hélène
authors.initials: H
authors.lastname: Guilloteau
authors.forename: Ghouti
authors.initials: G
authors.lastname: Medjahdi
authors.forename: Raphaël
authors.initials: R
authors.lastname: Schneider
mesh_terms: D000042:Absorption; D015374:Biosensing Techniques; D049109:Cell Proliferation / Q000187:drug effects; D049921:Cupriavidus / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects; D050296:Microbial Viability / Q000187:drug effects; D053758:Nanoparticles / Q000737:chemistry*; D019301:Oleic Acid / Q000737:chemistry; D045663:Quantum Dots; D012821:Silanes / Q000737:chemistry* / Q000494:pharmacology; D012833:Siloxanes / Q000737:chemistry / Q000494:pharmacology; D015032:Zinc / Q000737:chemistry / Q000494:pharmacology; D015034:Zinc Oxide / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D012821:Silanes; D012833:Siloxanes; D019301:Oleic Acid; D015032:Zinc; D015034:Zinc Oxide