Nanotechnology, Biology, and Medicine 3 95 — www. Stable Ag nanoparticles were prepared and their shape and size distribution characterized by particle characterizer and transmission electron microscopic study.
Abstract Among metal pollutants silver ions are one of the most toxic forms, and have thus been assigned to the highest toxicity class. Its toxicity to a wide range of microorganisms combined with its low toxicity to humans lead to the development of a wealth of silver-based products in many bactericidal applications accounting to more than nano-technology-based consumer products.
Accordingly, silver is a widely distributed metal in the environment originating from its different forms of application as metal, salt and nanoparticle. A realistic assessment of silver nanoparticle toxicity in natural waters is, however, problematic and needs to be linked to experimental approaches.
Here we apply metatranscriptome sequencing allowing for elucidating reactions of whole communities present in a water sample to stressors. We compared the toxicity of ionic silver and ligand-free silver nanoparticles by short term exposure on a natural community of aquatic microorganisms.
We analyzed the effects of the treatments on metabolic pathways and species composition on the eukaryote metatranscriptome level in order to describe immediate molecular responses of organisms using a community approach.
Our study therefore supports the view that ionic silver rather than silver nanoparticles are responsible for silver toxicity. Nevertheless, our results highlight the strength of metatranscriptome approaches for assessing metal toxicity on aquatic communities.
Introduction Engineered silver nanoparticles AgNP are used in a wide variety of applications, for example as antimicrobial additives in textiles, as household products and in medical applications.
So far, the impact of AgNP, as well as of ionic silver species on aquatic organisms has been studied mostly in laboratory experiments using single test species, sometimes even clonal cultures e.
As a general trend it appears that toxicity of silver is due to ionic silver as the molecular toxicant .
exert an inhibitory effect on bacteria; antiseptics, disinfectants, metals (Mercury Chloride, Silver Nitrate, Copper Sulfate) Paper Disk Method used to test the effect of chemical agents on bacteria; must take into account the diffusion rate of the chemical and the effect of the growth medium; saturate paper disks and place onto inoculated. At the same time, silver nitrate and sodium sulphadiazine was being formulated from silver nitrate and sodium sulphadiazine in order to combine the antibacterial effect of the sulphonamide moiety with the inhibitory effect of silver (Fox, ). The effects of AgNPs and Ag + on N 2 O emission were calculated on the basis of the percentage changes of N 2 O concentration (in the headspace of the glass vials) in the Ag treatments relative to .
Realistic assessment of nanoparticle toxicity mediated by their ionic forms in natural waters is difficult due to the interaction of nanoparticles and ions with other inorganic and organic molecules .
Accordingly, it is necessary to transfer laboratory results to field conditions. Also, the use of single species as test organisms as well as analyses of single parameters such as cell numbers or chlorophyll content will be insufficient if community effects and functional diversity of ecosystems are of interest .
In this context, a metatranscriptome sequencing approach is able to elucidate reactions of whole communities present in a water sample to stressors like toxic substances . Differential transcription of genes related to various metabolic pathways e.
Therefore, this method allows detection of possible environmental hazards in a realistic approach, taking into account the species community as a whole. To the best of our knowledge, no information exists on the effects of silver nitrate AgNO3 as compared to AgNP on aquatic communities to date.
Accordingly, we compared the toxicity of ionic silver and AgNP by short-term exposure of a natural community of aquatic microorganisms in a laboratory exposure experiment. Since the activity of AgNP is influenced by the ligands, ligand-free nanoparticles are especially suitable for such comparisons .
Effects of the treatments on metabolic pathways and species composition were analyzed on the eukaryote metatranscriptome level in order to describe immediate molecular responses of organisms using a community approach.
Approximately L of water containing a natural plankton community from a eutrophic pond at the campus Essen of the University Duisburg-Essen, Germany, were transferred to a L glass tank.
The next day, 10 L of pond water from the glass tank were filled to to nine 20 L plastic tanks respectively and aerated by aquarium pumps. Monitoring of silver concentrations during exposure was performed by Ag analyses of 10 ml water samples taken from each tank 30 min and 24 h after the start of exposure; from the silver exposed groups one additional water sample was drawn after 5 h following exposure start.
Half of the water samples were filtered 0.
These samples were considered to reflect the concentration of dissolved silver. The experiment was terminated after 24 h. Before exposure to silver, samples were taken for the metatranscriptomic sequence analysis 2.
After 24 h of exposure the same sample volumes were taken from each treatment group. Additionally, temperature, pH, conductivity and O2-concentration were measured twice during the exposure period in every tank.Effect of silver nano particles on fungi, bacteria, viruses and yeasts Different types of nano materials like copper, zinc, titanium alginate and silver have come up but silver nanoparticles have proved to be most effective due to its good antimicrobial efficacy against bacteria, viruses and other eukaryotic micro-.
At the same time, silver nitrate and sodium sulphadiazine was being formulated from silver nitrate and sodium sulphadiazine in order to combine the antibacterial effect of the sulphonamide moiety with the inhibitory effect of silver (Fox, ).
Fused Silver Nitrate, molded into sticks, was traditionally called lunar caustic. It is used as a cauterizing agent.
Silver Nitrate is melted at °C (°F) and poured into a mold of the desired shape. Silver Chloride is used as an Antibacterial agent for concrete (1 . Apr 22, · Nevertheless, AgNP can have toxic effects that are higher than expected according to the concentration of dissolved ionic silver, probably due to additional effects of particles and agglomerations on cell membranes, depending on various factors like media used, organic molecules, light conditions and particle size or NP coating.
exert an inhibitory effect on bacteria; antiseptics, disinfectants, metals (Mercury Chloride, Silver Nitrate, Copper Sulfate) Paper Disk Method used to test the effect of chemical agents on bacteria; must take into account the diffusion rate of the chemical and the effect of the growth medium; saturate paper disks and place onto inoculated.
All reagents were prepared in distilled deionized MilliQ water ( MΩ) using the following ACS-grade salts: silver sulfate (Ag 2 (SO 4)), sodium azide (NaN 3), ammonium phosphate monobasic (NH 4 H 2 PO 4), and ammonium sulfate ((NH 4) 2 SO 4)).