Featured Research

from universities, journals, and other organizations

Coated Film As A Bacteria Killer

Date:
August 13, 2008
Source:
Swiss Federal Institute Of Technology
Summary:
A nanoproduct made from silver and calcium phosphate is lethal to bacteria. Its special feature is that the bacteria themselves invoke and dispense this disinfectant effect.

The diagram shows the self-disinfecting action of the silver and calcium phosphate nanoparticles applied to the plastic film.
Credit: Image courtesy of Swiss Federal Institute Of Technology

A nanoproduct made from silver and calcium phosphate and developed by ETH Zurich researchers is lethal to bacteria. Its special feature is that the bacteria themselves invoke and dispense this disinfectant effect.

The fact that silver is an antiseptic and thus a disinfectant has been known for about 3000 years. This is why well-to-do households used silver cutlery, which has an antibacterial effect, while poorer people put silver coins in their milk jugs.

Silver was used medicinally for around two hundred years before it was replaced by antibiotics, and, for a long time, practically its only remaining use was in alternative medicine. The noble metal has undergone a kind of renaissance in medicine since the start of the nanotechnology era. Medical instruments, artificial limbs, hospital furniture or even hospital linen are lined, sheathed or fortified with it.

Nutrient substrate activates the mechanism

However, until now it has been impossible to use the noble metal in a specific, controlled amount. The research group led by Wendelin Stark, Assistant Professor at the Institute for Chemical and Bioengineering of ETH Zurich, has now developed a plastics film coated with silver and calcium phosphate that fulfils these conditions and, in addition, is self-disinfecting.

For example, the combination of the two substances has an effect on the bacterium Escherichia coli that is up to 1000 times more lethal than conventional silicon-based silver preparations. One decisive factor appears to be that the bacteria use the calcium substrate for their metabolism. The calcium phosphate particles, 20 to 50 nanometres in size, are absorbed by the micro-organisms as food and are thereby disintegrated. This releases thousands of tiny silver particles measuring 1 to 2 nanometres which the researchers had coated onto the calcium nutrient.

According to current knowledge, silver nanoparticles have multiple effects on bacteria: they suppress the cell’s nutrient transport, attack the cell membrane and interfere with cell division and thus with the reproduction of the germs. Experiments with the carrier substances calcium phosphate and silicon dioxide, each coated with silver, showed different effects on various bacterial strains in the test.

The calcium phosphate substrate had an efficiency factor of up to 1000 times stronger than silicon dioxide. Within 24 hours, less than one bacterium out of 100,000 to 1,000,000 bacteria survived. However, according to the researchers, since the consumption of the organic calcium phosphate also nourishes the bacteria – without the effect of the silver, they would multiply thousand-fold in 24 hours – the silver must fight not only the bacteria that already exist but also those that would newly form. Wendelin Stark says, “This makes the effect even more astonishing.”

Reducing the risk of infection

The new product has enabled Stark’s group to successfully develop a preparation that is effective against a series of pathogenic bacteria and which becomes active in a targeted manner and in the correct dose only if a bacterium is present. The silver adhering to the calcium phosphate is only released in a quantity corresponding to the amount of calcium phosphate consumed by the bacterium. This saves costs, is efficient and is less stressful for the human body. The product is already being manufactured by the Perlen Converting AG Company in Perlen near Lucerne, which was involved in the development.

This involves coating a film with nanoparticles of silver and calcium phosphate. The film can be used in hospitals, for example, hotspots for germ transmission. Door handles, beds or sanitary equipment onto which the self-disinfecting film is stuck could protect patients from dreaded and dangerous hospital pathogens that can lead to complications, for example after surgical operations. It must be renewed from time to time because the bacteria consume and use up the calcium, so the film is not effective indefinitely.


Story Source:

The above story is based on materials provided by Swiss Federal Institute Of Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Loher S, Schneider OD, Maienfisch T, Borkony S, Stark WJ. Micro-organism-Triggered Release of Silver Nanoparticles from Biodegradable Oxide Carriers Allows Preparation of Self-Sterilizing Polymer Surfaces. Small, 2008; 4 (6), 824-832 DOI: 10.1002/smll.200800047

Cite This Page:

Swiss Federal Institute Of Technology. "Coated Film As A Bacteria Killer." ScienceDaily. ScienceDaily, 13 August 2008. <www.sciencedaily.com/releases/2008/08/080811091257.htm>.
Swiss Federal Institute Of Technology. (2008, August 13). Coated Film As A Bacteria Killer. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2008/08/080811091257.htm
Swiss Federal Institute Of Technology. "Coated Film As A Bacteria Killer." ScienceDaily. www.sciencedaily.com/releases/2008/08/080811091257.htm (accessed July 28, 2014).

Share This




More Plants & Animals News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. Video provided by Newsy
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. 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:
from the past week

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