Featured Research

from universities, journals, and other organizations

Nanosilver: A new name -- well-known effects

Date:
January 31, 2011
Source:
Swiss Federal Laboratories for Materials Science and Technology (EMPA)
Summary:
Nanosilver is not a new discovery by nanotechnologists -- it has been used in various products for over a hundred years, as is shown by a new study. The antimicrobial effects of minute silver particles, which were then known as "colloidal silver," were known from the earliest days of its use.

TEM image of silver nanoparticles in the algicide Algaedyn used for swimming pools.
Credit: Image courtesy of Swiss Federal Laboratories for Materials Science and Technology (EMPA)

Nanosilver is not a new discovery by nanotechnologists -- it has been used in various products for over a hundred years, as is shown by a new Empa study. The antimicrobial effects of minute silver particles, which were then known as "colloidal silver," were known from the earliest days of its use.

Related Articles


Numerous nanomaterials are currently at the focus of public attention. In particular silver nanoparticles are being investigated in detail, both by scientists as well as by the regulatory authorities. The assumption behind this interest is that they are dealing with a completely new substance.

However, Empa researchers Bernd Nowack and Harald Krug, together with Murray Heights of the company HeiQ have shown in a paper recently published in the journal Environmental Science & Technology that nanosilver is by no means the discovery of the 21st century. Silver particles with diameters of seven to nine nm were mentioned as early as 1889. They were used in medications or as biocides to prevent the growth of bacteria on surfaces, for example in antibacterial water filters or in algaecides for swimming pools.

The material has always been the same

The nanoparticles were known as "colloidal silver" in those days, but what was meant was the same then as now -- extremely small particles of silver. The only new aspect is the use today of the prefix "nano." "However," according to Bernd Nowack, "nano does not mean something new, and nor does it mean something that is harmful."

When "colloidal silver" became available on the market in large quantities in the 1920s it was the topic of numerous studies and subject to appropriate regulation by the authorities. Even in those days the significance of the discovery of nanoparticles and how they worked was realized.

"That is not to say that the possible side-effects of nanoparticles on humans and the environment should be played down or ignored," adds Nowack. It is important to characterize in exact detail the material properties of nanosilver and not just to believe unquestioningly the doubts and reservations surrounding the product.

Nanosilver has different effects than silver

The term nanoparticle is understood to refer to particles whose dimensions are less than 100 nm. Because of their minute size nanoparticles have different properties than those of larger particles of the same material. For example, for a given volume nanoparticles have a much greater surface area, so they are frequently much more reactive than the bulk material. In addition, even in small quantities nanosilver produces more silver ions than solid silver. These silver ions are toxic to bacteria. Whether or not nanosilver represents a risk to humans and the environment is currently the subject of a great deal of investigation.

Nanosilver in wastewater treatment plants

Currently there are hundreds of products in circulation which contain silver nanoparticles. Examples include cosmetics, food packaging materials, disinfectants, cleaning agents and -- not least -- antibacterial socks and underwear. Every year some 320 tonnes of nanosilver are used worldwide, some of which is released into wastewater, thus finding its way into natural water recirculation systems. What effects solar particles have on rivers, soil and the organisms that live in them has not yet been clarified in detail.

A commentary by Bernd Nowack in the journal Science discusses the implications of the newest studies on nanosilver in sewage treatment plants. More than 90% remains bound in the sewage sludge in the form of silver sulfide, a substance which is extremely insoluble and orders of magnitude less poisonous than free silver ions. It apparently does not matter what the original form of the silver in the wastewater was, whether as metallic nanoparticles, as silver ions in solution or as precipitated insoluble silver salts.

"As far as the environmental effects are concerned, it seems that nanosilver in consumer goods is no different than other forms of silver and represents only a minor problem for eco-systems," says Nowack.

What is still to be clarified, however, is in what form the unbound silver is present in the treated water released from sewage works, and what happens to the silver sulfide in natural waters. Is this stable and unreactive or is it transformed into other forms of silver?


Story Source:

The above story is based on materials provided by Swiss Federal Laboratories for Materials Science and Technology (EMPA). Note: Materials may be edited for content and length.


Journal References:

  1. Bernd Nowack, Harald F. Krug, Murray Height. 120 Years of Nanosilver History: Implications for Policy Makers. Environmental Science & Technology, 2011; 110110081514045 DOI: 10.1021/es103316q
  2. B. Nowack. Nanosilver Revisited Downstream. Science, 2010; 330 (6007): 1054 DOI: 10.1126/science.1198074

Cite This Page:

Swiss Federal Laboratories for Materials Science and Technology (EMPA). "Nanosilver: A new name -- well-known effects." ScienceDaily. ScienceDaily, 31 January 2011. <www.sciencedaily.com/releases/2011/01/110131133005.htm>.
Swiss Federal Laboratories for Materials Science and Technology (EMPA). (2011, January 31). Nanosilver: A new name -- well-known effects. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2011/01/110131133005.htm
Swiss Federal Laboratories for Materials Science and Technology (EMPA). "Nanosilver: A new name -- well-known effects." ScienceDaily. www.sciencedaily.com/releases/2011/01/110131133005.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
3D Printed Cookies Just in Time for Christmas

3D Printed Cookies Just in Time for Christmas

Reuters - Innovations Video Online (Dec. 18, 2014) A tech company in Spain have combined technology with cuisine to develop the 'Foodini', a 3D printer designed to print the perfect cookie for Santa. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
First Etihad Superjumbo Flight in December

First Etihad Superjumbo Flight in December

AFP (Dec. 18, 2014) The first flight of Etihad Airways' long-awaited Airbus A380 superjumbo will take place later in December, the Abu Dhabi carrier said Thursday, also announcing its first Boeing 787 Dreamliner route. Duration: 01:09 Video provided by AFP
Powered by NewsLook.com
Ford Expands Air Bag Recall Nationwide

Ford Expands Air Bag Recall Nationwide

Newsy (Dec. 18, 2014) The automaker added 447,000 vehicles to its recall list, bringing the total to more than 502,000. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins