Navigation Links
Is nanosilver toxic?
Date:2/28/2013

For his doctoral dissertation Niskanen has been studying several hybrid nanomaterials, i.e. combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles. He will defend his doctoral thesis at the University of Helsinki in April.

Part of the magic of nano-science is that on the scale of a billionth of a metre, matter and materials behave in ways that are not yet known. Neither is it always known what types of effects the nano version of the parent matter will have on its environment.

"Due to the fact that silver in nanoparticle form is bactericidal and also fungicidal and also prevents the reproduction of those organisms, it is now used in various consumer goods ranging from wound dressing products to sportswear," says Niskanen from the Laboratory of Polymer Chemistry at the University of Helsinki, Finland.

While the usefulness of silver has been established, the debate over the toxicity mechanisms of its various forms to microorganisms but also to non-target species continues. Anne Kahru, Head of the Laboratory of Environmental Toxicology at the National Institute of Chemical Physics and Biophysics, Estonia, talks about a whole new field of ecotoxicology: nanoecotoxicology.

So far, little is known about the environmental effects of silver nanoparticles and their toxicity to aquatic organisms. A joint study from the University of Helsinki and the National Institute of Chemical Physics and Biophysics (Tallinn, Estonia), "Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus", shows that silver nanoparticles are apparently no more hazardous to aquatic ecosystems than a water-soluble silver salt. The study compared the ecotoxicity of silver nanoparticles and a water-soluble silver salt.

"Our conclusion was that the environmental risks caused by silver nanoparticles are seemingly not higher than those caused by a silver salt. However, more research is required to reach a clear understanding of the safety of silver-containing particles," Niskanen says.

Indeed, silver nanoparticles were found to be ten times less toxic than the soluble silver nitrate a soluble silver salt used for the comparison.

The bioavailability of silver varies in different test media

To explain this phenomenon, the researchers refer to the variance in the bioavailability of silver to crustaceans in different tested media.

University lecturer Olli-Pekka Penttinen from the Department of Environmental Sciences of the University of Helsinki goes on to note that the inorganic and organic compounds dissolved in natural waters (such as humus), water hardness and sulfides have a definite impact on the bioavailability of silver. Due to this, the toxicity of both types of tested nanoparticles and the silver nitrate measured in the course of the study was lower in natural water than in artificial fresh water.

The toxicity of silver nanoparticles and silver ions was studied using two aquatic crustaceans, a water flea (Daphnia magna) and a fairy shrimp (Thamnocephalus platyurus). Commercially available protein-stabilised particles and particles coated with a water-soluble, non-toxic polymer, specifically synthesised for the purpose, were used in the study. First, the polymers were produced utilising a controlled radical polymerisation method. Synthetic polymer-grafted silver particles were then produced by attaching the water-soluble polymer to the surface of the silver with a sulfur bond.

Jukka Niskanen has utilised such polymerisation and coupling reactions in his doctoral dissertation, Polymeric and hybrid materials: polymers on particle surfaces and air-water interfaces, studying several hybrid nanomaterials, i.e., combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles. Niskanen will defend his doctoral thesis in the field of polymer chemistry at the University of Helsinki in April 2013.

It was previously known from other studies and research results that silver changes the functioning of proteins and enzymes. It has also been shown that silver ions can prevent the replication of DNA. Concerning silver nanoparticles, tests conducted on various species of bacteria and fungi have indicated that their toxicity varies. For example, gram-negative bacteria such as Escherichia coli are more sensitive to silver nanoparticles than gram-positive ones (such as Staphylococcus aureus). The difference in sensitivity is caused by the structural differences of the cell membranes of the bacteria. The cellular toxicity of silver nanoparticles in mammals has been studied as well. It has been suggested that silver nanoparticles enter cells via endocytosis and then function in the same manner as in bacterial cells, damaging DNA and hindering cell respiration. Electron microscope studies have shown that human skin is permeable to silver nanoparticles and that the permeability of damaged skin is up to four times higher than that of healthy skin.


'/>"/>
Contact: Jukka Niskanen
jukka.niskanen@helsinki.fi
University of Helsinki
Source:Eurekalert

Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/8/2016)... PRAGUE, Czech Republic , February 8, 2016 ... first EU-regulated global payment platform which presents innovation ... Voice Biometrics Authentication feature called VoiceKey. --> ... payment platform which presents innovation for clients, comfort ... feature called VoiceKey. --> Worldcore ...
(Date:2/3/2016)... --> --> ... Fingerprint Identification System Market by Component (Hardware and Software), ... Finance, Government, Healthcare, and Transportation) and Geography - Global ... expected to be worth USD 8.49 Billion by 2020 ... 2020. The transformation and technology evolution from the manual ...
(Date:2/2/2016)... , Feb. 2, 2016 This BCC ... bioinformatic market by reviewing the recent advances in ... that drive the field forward. Includes forecast through ... Identify the challenges and opportunities that exist in ... software solution developers, as well as IT and ...
Breaking Biology News(10 mins):
(Date:2/11/2016)... ... 11, 2016 , ... Global Stem Cells Group, ... Global Stem Cells Network (GSCN) to distribute exosome injection and other biological products ... Costa Rica, Dominican Republic, Colombia, Argentina, Nicaragua, Panama, El Salvador, Venezuela, Peru, Ecuador, ...
(Date:2/10/2016)... NX Prenatal Inc., a US based ... for early warning of adverse pregnancy outcomes, announced ... by Dr. Thomas McElrath of Brigham ... Medicine,s (SMFM) annual meeting held in ... The presentation reported initial positive top-line results regarding ...
(Date:2/10/2016)... , Feb. 10, 2016  Matchbook, Inc., ... for fast growing biotech companies, announced today the ... Procurement Strategic Advisor. Jim brings nearly 25 years ... and procurement, having spent nearly two decades in ... Chain/Logistics and Procurement at Genzyme and, most recently ...
(Date:2/10/2016)... ... February 10, 2016 , ... ... a research registry built on the secure online PatientCrossroads platform, has exceeded both ... 1,600 participants have joined the PROMPT study, which seeks to advance understanding of ...
Breaking Biology Technology: