title: Size-dependent toxicity of silver nanoparticles to bacteria, yeast, algae, crustaceans and mammalian cells in vitro.
abstract: The concept of nanotechnologies is based on size-dependent properties of particles in the 1-100 nm range. However, the relation between the particle size and biological effects is still unclear. The aim of the current paper was to generate and analyse a homogenous set of experimental toxicity data on Ag nanoparticles (Ag NPs) of similar coating (citrate) but of 5 different primary sizes (10, 20, 40, 60 and 80 nm) to different types of organisms/cells commonly used in toxicity assays: bacterial, yeast and algal cells, crustaceans and mammalian cells in vitro. When possible, the assays were conducted in ultrapure water to minimise the effect of medium components on silver speciation. The toxic effects of NPs to different organisms varied about two orders of magnitude, being the lowest (∼0.1 mg Ag/L) for crustaceans and algae and the highest (∼26 mg Ag/L) for mammalian cells. To quantify the role of Ag ions in the toxicity of Ag NPs, we normalized the EC50 values to Ag ions that dissolved from the NPs. The analysis showed that the toxicity of 20-80 nm Ag NPs could fully be explained by released Ag ions whereas 10 nm Ag NPs proved more toxic than predicted. Using E. coli Ag-biosensor, we demonstrated that 10 nm Ag NPs were more bioavailable to E. coli than silver salt (AgNO3). Thus, one may infer that 10 nm Ag NPs had more efficient cell-particle contact resulting in higher intracellular bioavailability of silver than in case of bigger NPs. Although the latter conclusion is initially based on one test organism, it may lead to an explanation for "size-dependent" biological effects of silver NPs. This study, for the first time, investigated the size-dependent toxic effects of a well-characterized library of Ag NPs to several microbial species, protozoans, algae, crustaceans and mammalian cells in vitro.
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Angela
authors.initials: A
authors.lastname: Ivask
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Imbi
authors.initials: I
authors.lastname: Kurvet
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Kaja
authors.initials: K
authors.lastname: Kasemets
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Irina
authors.initials: I
authors.lastname: Blinova
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Villem
authors.initials: V
authors.lastname: Aruoja
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Sandra
authors.initials: S
authors.lastname: Suppi
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Heiki
authors.initials: H
authors.lastname: Vija
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Käkinen
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Tiina
authors.initials: T
authors.lastname: Titma
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Margit
authors.initials: M
authors.lastname: Heinlaan
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia; Institute of Physics, Faculty of Science and Technology, University of Tartu, Tartu, Estonia.
authors.forename: Meeri
authors.initials: M
authors.lastname: Visnapuu
authors.affiliation: Biomineral Research Group, Medical Research Council Human Nutrition Research, Cambridge, United Kingdom.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Koller
authors.affiliation: Institute of Physics, Faculty of Science and Technology, University of Tartu, Tartu, Estonia.
authors.forename: Vambola
authors.initials: V
authors.lastname: Kisand
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.
authors.forename: Anne
authors.initials: A
authors.lastname: Kahru
mesh_terms: D000818:Animals; D041702:BALB 3T3 Cells; D000460:Chlorophyta / Q000187:drug effects; D003621:Daphnia / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D053768:Metal Nanoparticles / Q000633:toxicity* / Q000648:ultrastructure; D051379:Mice; D010316:Particle Size; D011551:Pseudomonas fluorescens / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000187:drug effects; D012834:Silver / Q000633:toxicity*
chemical_list: D012834:Silver