Profiling of the toxicity mechanisms of coated and uncoated silver nanoparticles to yeast Saccharomyces cerevisiae BY4741 using a set of its 9 single-gene deletion mutants defective in oxidative stress response, cell wall or membrane integrity and endocytosis.
The widespread use of nanosilver in various antibacterial, antifungal, and antiviral products warrants the studies of the toxicity pathways of nanosilver-enabled materials toward microbes and viruses. We profiled the toxicity mechanisms of uncoated, casein-coated, and polyvinylpyrrolidone-coated silver nanoparticles (AgNPs) using Saccharomyces cerevisiae wild-type (wt) and its 9 single-gene deletion mutants defective in oxidative stress (OS) defense, cell wall/membrane integrity, and endocytosis. The 48-h growth inhibition assay in organic-rich growth medium and 24-h cell viability assay in deionized (DI) water were applied whereas AgNO3, H2O2, and SDS served as positive controls. Both coated AgNPs (primary size 8-12nm) were significantly more toxic than the uncoated (~85nm) AgNPs. All studied AgNPs were ~30 times more toxic if exposed to yeast cells in DI water than in the rich growth medium: the IC50 based on nominal concentration of AgNPs in the growth inhibition test ranged from 77 to 576mg Ag/L and in the cell viability test from 2.7 to 18.7mg Ag/L, respectively. Confocal microscopy showed that wt but not endocytosis mutant (end3Δ) internalized AgNPs. Comparison of toxicity patterns of wt and mutant strains defective in OS defense and membrane integrity revealed that the toxicity of the studied AgNPs to S. cerevisiae was not caused by the OS or cell wall/membrane permeabilization.
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia; Faculty of Chemical and Materials Technology, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia. Electronic address: sandra.kaosaar@kbfi.ee.
Sandra
S
Käosaar
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia. Electronic address: anne.kahru@kbfi.ee.
Anne
A
Kahru
Department of Earth and Environmental Sciences, Research Centre POLARIS, University of Milano-Bicocca, 1 Piazza della Scienza, Milano 20126, Italy. Electronic address: paride.mantecca@unimib.it.
Paride
P
Mantecca
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia. Electronic address: kaja.kasemets@kbfi.ee.
Kaja
K
Kasemets
D002364:Caseins / Q000737:chemistry / Q000633:toxicity; D002463:Cell Membrane Permeability; D002473:Cell Wall; D004705:Endocytosis; D017353:Gene Deletion; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D018613:Microscopy, Confocal; D018384:Oxidative Stress / Q000187:drug effects; D011205:Povidone / Q000737:chemistry / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012834:Silver / Q000737:chemistry / Q000633:toxicity*
D002364:Caseins; D017382:Reactive Oxygen Species; D012834:Silver; D011205:Povidone
Dissolution; EUROSCARF strains; Endocytosis; Silver nanoparticles; Speciation