Toxicity of 12 metal-based nanoparticles to algae, bacteria and protozoa

Abstract

The use of metal based nanoparticles (NPs) is increasing which leads to their release in water bodies via various waste streams and warrants risk assessment. Consistent biological effect data on NPs for environmentally relevant test species that are accompanied by thorough characterization of NPs are scarce but indispensable for understanding possible risks of NPs. We composed and tested a library of 12 metal-based nanoparticles () using alga Pseudokirchneriella subcapitata, three bacterial species (Vibrio fischeri, Escherichia coli, Staphylococcus aureus) and protozoan Tetrahymena thermophila. The NPs were characterized for physico-chemical properties, solubility and abiotic reactive oxygen species (ROS) production. Also, respective soluble salts were analysed for toxic effects. The algal growth inhibition assay proved the most sensitive and yielded EC 50 values for 10 NPs ranging from 0.1 to 58 mg/l. Algal toxicity correlated with abiotic ROS production of NPs and the majority of NPs formed agglomerates that entrapped algal cells. Despite of different sensitivity, there was a common trend in the toxicity of NPs across different species and test formats: CuO and ZnO had highest toxicity (EC 50 values below 1 mg/l) to all organism groups except protozoa. The high toxicity was mostly due to shedding of toxic concentrations of Zn and Cu ions; for most of the test species Al 2 O 3 , SiO 2 , WO 3 and Sb 2 O 3 were not toxic below 100 mg/l and MgO showed no adverse effect below 100 mg/l to any test species in any test setting. Nano impactThe lack of good quality nanotoxicity data for environmentally relevant test species accompanied by physico-chemical characterization of nanoparticles (NPs) severely hampers risk assessment. This study provides biological response data of a thoroughly characterized library of metal-based NPs using algal, bacterial and protozoan tests. It includes correlations between NP properties and toxicity, as well as results obtained in deionized water, thus eliminating medium-specific effects. Similar trends across species are shown, although algae proved the most sensitive. EC 50 values of 10 NPs ranged from 0.1 to 58 mg/l. The values may be used for toxicity modelling or directly for risk assessment, as the 72 h algal growth inhibition data are mandatory for the registration of chemicals in the European Union.EC 50 -half effective concentration; MBC -Minimal Biocidal Concentration, i.e., the lowest tested nominal concentration of NPs which completely inhibited the formation of visible colonies after sub-culturing on toxicant-free agarised growth medium. Prior subculturing bacteria were incubated with NPs for 24 h at 25 °C in deionised water.

Safe-by-Design CuO NanoparticlesviaFe-Doping, Cu–O Bond Length Variation, and Biological Assessment in Cells and Zebrafish Embryos

“…23, 46, 81–83 The biological response was then delineated by engineering ZnO NPs via Fe doping. 46, 84–86 In the present investigation, the decreased toxicity at cellular level and the reduced hatching interference in the zebrafish embryo (safe-by-design strategy) is established for Fe doped CuO NPs (Figure 12).…”

Fabrication of silver chloride nanoparticles using a plant serine protease in combination with photoactivation and investigation of their biological activities

“…C). The effects of agglomerated nanoparticles within some protozoa have been reported: Not all types of nanoparticle caused acute toxicity in the protozoa Tetrahymena thermophile (24 H EC 50 >1,000 mg/mL) , and nontoxic nanotitanium dioxide (nTiO2) could agglomerate in Paramecium .…”

Metal(loid) oxide (Al2O3, Mn3O4, SiO2 and SnO2) nanoparticles cause cytotoxicity in yeast via intracellular generation of reactive oxygen species

“…MOx NPs agglomeration was also characterized by a sedimentation assay (Aruoja et al 2015;Hartmann et al 2013;OECD 2017). For this purpose, NPs were suspended in YEP or MES buffer, at a final concentration of 100 mg/L, and agitated at 150 rpm for 24 h, at 30°C, in the absence of yeast cells.…”

“…Studies in soils showed that Al 2 O 3 , SiO 2 and SnO 2 NPs had an impact in bacterial and in fungal community (Chai et al 2015;Chavez-Calderon et al 2016;McGee et al 2017). Other studies showed that Al 2 O 3 , Mn 3 O 4 and SiO 2 NPs caused growth inhibition of bacteria (Escherichia coli and Staphylococcus aureus), algae (Pseudokirchneriella subcapitata) and protozoa (Tetrahymena thermophila and Paramecium multimicronucleatum) and bioluminescence reduction of the bacterium Vibrio fischeri (Aruoja et al 2015;Li et al 2012). SnO 2 NPs caused a reduction of cell viability and provoked the damage of cell membrane in the bacteria E. coli and Bacillus subtilis (Chavez-Calderon et al 2016).…”