41 research outputs found
Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles : Magnetic and safety properties
Spherical nickel particles with size in the range of 100-400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.Peer reviewe
Toxicity of Ag, CuO and ZnO nanoparticles to selected environmentally relevant test organisms and mammalian cells in vitro: a critical review
Effect of changing environmental conditions on the fermentative growth of Saccharomyces cerevisiae S288C: Auxo-accelerostat study
Toxicity of ZnO and CuO nanoparticles to ciliated protozoa Tetrahymena thermophila
The toxic effects of nanoparticles (NPs) of ZnO and CuO to particle-ingesting model organism protozoa Tetrahymena thermophila were evaluated. Nano-ZnO was remarkably more toxic than nano-CuO (EC50 values ∼5mgmetal/l versus 128mgmetal/l). Toxic effect of CuO depended on particle size: nano-CuOwas about 10–20 times more toxic than bulk CuO. However, when calculated on basis of bioavailable copper (quantified using recombinant Cu-sensor bacteria) the 4-h EC50 values of nano- and bulk formulations were comparable (2.7 and 1.9mg bioavailable Cu/l, respectively), and statistically different from the EC50 value of Cu2+ (1.1 mg/l). Differently from CuO particles, bulk and nanosized ZnO as well as Zn2+ were of similar toxicity (4-h EC50 values 3.7 and 3.9mg bioavailable Zn/l, respectively, and 4.9mg Zn2+/l). Thus, the toxic effect of both, CuO and ZnO (nano)particles to protozoawas caused by their solubilised fraction. The toxic effects of the copper compounds were not dependent on exposure time (4 and 24 h), whereas the toxicity of zinc compounds was about 1.5 times lower after 24 h of exposure than after 4 h, probably due to adaptation. In summary, we recommend T. thermophila as a simple eukaryotic particle-ingesting model organism for the toxicity screening of NPs. For the high throughput testing we suggest to use the 4-h assay on microplates using ATP and/or propidium iodide for the evaluation of cell viability
Extracellular conversion of silver ions into silver nanoparticles by protozoan Tetrahymena thermophila
In the current study, cell-free exudates of the ciliated protozoan Tetrahymena thermophila were shown to progressively convert silver nitrate to silver nanoparticles (Ag NPs) under illumination at ambient temperature. The formation of Ag NPs in the reaction mixture was evidenced by gradual colour changes, appearance of a specific absorbance peak (420–450 nm) and visualization using scanning electron microscopy coupled to an energy-dispersive X-ray spectrometer. After 2 h of incubation the mean hydrodynamic size of the Ag NPs was 70 nm. Seven days of incubation resulted in larger agglomerates and a significant decrease in silver toxicity to T. thermophila, accompanied by about 100-fold reduction in the silver ion concentration. Protein analysis indicated an extensive extracellular protein binding by the Ag NPs formed in the protozoan exudates. As protozoa are important components in wastewater treatment, their ability to sequester silver ions into a less bioavailable and less toxic form of silver (e.g. NPs) may be one of the adaption mechanisms of ciliate survival in contaminated environments
Exposure to CuO nanoparticles changes the fatty acid composition of protozoa Tetrahymena thermophila
Biotests and Biosensors for Ecotoxicology of Metal Oxide Nanoparticles: A Minireview
Nanotechnologies have become a significant priority worldwide. Several manufactured nanoparticles - particles with one dimension less than 100 nm - are increasingly used in consumer products. At nanosize range, the properties of materials differ substantially from bulk materials of the same composition, mostly due to the increased specific surface area and reactivity, which may lead to increased bioavailability and toxicity. Thus, for the assessment of sustainability of nanotechnologies, hazards of manufactured nanoparticles have to be studied. Despite all the above mentioned, the data on the potential environmental effects of nanoparticles are rare. This mini-review is summarizing the emerging information on different aspects of ecotoxicological hazard of metal oxide nanoparticles, focusing on TiO2, ZnO and CuO. Various biotests that have been successfully used for evaluation of ecotoxic properties of pollutants to invertebrates, algae and bacteria and now increasingly applied for evaluation of hazard of nanoparticles at different levels of the aquatic food-web are discussed. Knowing the benefits and potential drawbacks of these systems, a suite of tests for evaluation of environmental hazard of nanoparticles is proposed. Special attention is paid to the influence of particle solubility and to recombinant metal-sensing bacteria as powerful tools for quantification of metal bioavailability. Using recombinant metal-specific bacterial biosensors and multitrophic ecotoxicity assays in tandem will create new scientific knowledge on the respective role of ionic species and of particles in toxicity of metal oxide nanoparticles
Toxicity of differently sized and charged silver nanoparticles to yeast Saccharomyces cerevisiae
Upon exposure to Cu nanoparticles, the accumulation of copper in the isopod Porcellio scaber is due to the dissolved Cu ions inside the digestive tract
The fate of nanoparticles in organisms is of significant interest.
In the current work, we used a test system with terrestrial isopods
(<i>Porcellio scaber</i>) fed with food spiked with Cu NPs
or soluble Cu salt for 14 days. Two different doses were used for
spiking to yield final concentrations of 2000 and 5000 μg Cu/g
dry food. After the exposure period, part of the exposed group of
animals was transferred to clean food to depurate. Cu content was
analyzed in the digestive glands, gut, and the ‘rest’
of the body. Similar patterns of (i) assimilated and depurated amounts
of Cu, (ii) Cu body distribution, and (iii) effect on isopods feeding
behavior were observed regardless of whether the animals were fed
with Cu NPs or soluble Cu salt spiked food. Thus, Cu ions and not
Cu NPs were assimilated by the digestive gland cells. Solubilization
of the Cu NPs applied to the leaves was also analyzed with chemical
methods and recombinant Cu-sensing bacteria. The comparison of the
in vitro data on solubilization of Cu NPs and in vivo data on Cu accumulation
in the animal tissues showed that about 99% of accumulated copper
ions was dissolved from ingested Cu NPs in the digestive system of
isopods