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Toxicity of CuO nanoparticles to yeast Saccharomyces cerevisiae BY4741 wild-type and its nine isogenic single-gene deletion mutants.

Chemical research in toxicology (2013-01-24)
Kaja Kasemets, Sandra Suppi, Kai Künnis-Beres, Anne Kahru

A suite of eight tentatively oxidative stress response-deficient Saccharomyces cerevisiae BY4741 single-gene mutants (sod1Δ, sod2Δ, yap1Δ, cta1Δ, ctt1Δ, gsh1Δ, glr1Δ, and ccs1Δ) and one copper-vulnerable mutant (cup2Δ) was used to elucidate weather the toxicity of CuO nanoparticles to S. cerevisiae is mediated by oxidative stress (OS). Specifically, sensitivity profiles of mutants' phenotypes and wild-type (wt) upon exposure to nano-CuO were compared. As controls, CuSO4 (solubility), bulk-CuO (size), H2O2, and menadione (OS) were used. Growth inhibition of wt and mutant strains was studied in rich YPD medium and cell viability in deionized water (DI). Dissolved Cu-ions were quantified by recombinant metal-sensing bacteria and chemical analysis. To wt strain nano-CuO was 32-fold more toxic than bulk-CuO: 24-h IC50 4.8 and 155 mg/L in DI and 643 and >20000 mg/L in YPD, respectively. In toxicant-free YPD medium, all mutants had practically similar growth patterns as wt. However, the mutant strains sod1Δ, sod2Δ, ccs1Δ, and yap1Δ showed up to 12-fold elevated sensitivity toward OS standard chemicals menadione and H2O2 but not to nano-CuO, indicating that CuO nanoparticles exerted toxicity to yeast cells via different mechanisms. The most vulnerable strain to all studied Cu compounds was the copper stress response-deficient strain cup2Δ (∼16-fold difference with wt), indicating that the toxic effect of CuO (nano)particles proceeds via dissolved Cu-ions. The dissolved copper solely explained the toxicity of nano-CuO in DI but not in YPD. Assumingly, in YPD nano-CuO acquired a coating of peptides/proteins and sorbed onto the yeast's outer surface, resulting in their increased solubility in the close vicinity of yeast cells and increased uptake of Cu-ions that was not registered by the assays used for the analysis of dissolved Cu-ions in the test medium. Lastly, as yeast retained its viability in DI even by 24th hour of incubation, the profiling of the acute basal toxicity of chemicals toward yeasts may be conducted in DI.

Product Number
Product Description

甲萘醌, crystalline
氧化铜, nanopowder, <50 nm particle size (TEM)
氧化铜, ACS reagent, ≥99.0%
氧化铜, powder, 99.99% trace metals basis
亚硫酸氢钠甲萘醌, ≥95% (TLC)
甲萘醌, meets USP testing specifications
氧化铜, powder, <10 μm, 98%
甲萘醌 (K3), analytical standard
亚硫酸氢钠甲萘醌, BioReagent, suitable for cell culture, ≥95% (TLC)
铝基氧化铜, 14-30 mesh, extent of labeling: 13 wt. % loading
氧化铜, 99.999% trace metals basis
氧化铜, needles, mixture of CuO and Cu2O, ACS reagent
氧化铜, powder, 99.995% trace metals basis
甲萘醌, European Pharmacopoeia (EP) Reference Standard