Featured Research

from universities, journals, and other organizations

Selenium suppresses staph on implant material

Date:
June 21, 2012
Source:
Brown University
Summary:
A coating of selenium nanoparticles significantly reduces the growth of Staphylococcus aureus on polycarbonate, a material common in implanted devices such as catheters and endotracheal tubes, engineers report.

Qi Wang swirls a solution of selenium nanoparticles in the lab. Coatings of the nanoparticles appear effective in fighting staph bacteria in medical device materials, according to a new study.
Credit: Webster Lab/Brown University

A coating of selenium nanoparticles significantly reduces the growth of Staphylococcus aureus on polycarbonate, a material common in implanted devices such as catheters and endotracheal tubes, engineers at Brown University report in a new study.

Selenium is an inexpensive element that naturally belongs in the body. It is also known to combat bacteria. Still, it had not been tried as an antibiotic coating on a medical device material. In a new study, Brown University engineers report that when they used selenium nanoparticles to coat polycarbonate, the material of catheters and endotracheal tubes, the results were significant reductions in cultured populations of Staphylococcus aureus bacteria, sometimes by as much as 90 percent.

"We want to keep the bacteria from generating a biofilm," said Thomas Webster, professor of engineering and orthopaedics, who studies how nanotechnology can improve medical implants. He is the senior author of the paper, published online this week in the Journal of Biomedical Materials Research A.

Biofilms are notoriously tough colonies of bacteria to treat because they are often able to resist antibiotic drugs.

"The longer we can delay or inhibit completely the formation of these colonies, the more likely your immune system will clear them," Webster said. "Putting selenium on there could buy more time to keep an endotracheal tube in a patient."

Meanwhile, Webster said, because selenium is actually a recommended nutrient, it should be harmless in the body at the concentrations found in the coatings. Also, it is much less expensive than silver, a less biocompatible material that is the current state of the art for antibacterial medical device coatings.

Webster has been investigating selenium nanoparticles for years, mostly for their possible anticancer effects. As he began to look at their antibiotic properties, he consulted with Hasbro Children's Hospital pediatrician Keiko Tarquinio, assistant professor of pediatrics, who has been eager to find ways to reduce biofilms on implants.

Studying selenium

For this study, Webster and first author Qi Wang grew selenium nanoparticles of two different size ranges and then used solutions of them to coat pieces of polycarbonate using a quick, simple process. On some of the polycarbonate, they then applied and ripped off tape not only to test the durability of the coatings but also to see how a degraded concentration of selenium would perform against bacteria.

On coated polycarbonate -- both the originally coated and the tape-tested pieces -- Wang and Webster used electron and atomic force microscopes to measure the concentration of nanoparticles and how much surface area of selenium was exposed to interact with bacteria.

One of their findings was that after the tape test, smaller nanoparticles adhered better to the polycarbonate than larger ones.

Then they were ready for the key step: experiments that exposed cultured staph bacteria to polycarbonate pieces, some of which were left uncoated as controls. Among the coated pieces, some had the larger nanoparticles and some had the smaller ones. Some from each of those groups had been degraded by the tape, and others had not.

All four types of selenium coatings proved effective in reducing staph populations after 24, 48, and 72 hours compared to the uncoated controls. The most potent effects -- reductions larger than 90 percent after 24 hours and as much as 85 percent after 72 hours -- came from coatings of either particle size range that had not been degraded by the tape. Among those coatings that had been subjected to the tape test, the smaller nanoparticle coatings proved more effective.

Staph populations exposed to any of the coated polycarbonate pieces peaked at the 48-hour timeframe, perhaps because that is when the bacteria could take fullest advantage of the in vitro culture medium. But levels always fell back dramatically by 72 hours.

The next step, Webster said, is to begin testing in animals. Such in vivo experiments, he said, will test the selenium coatings in a context where the bacteria have more available food but will also face an immune system response.

The results may ultimately have commercial relevance. Former graduate students developed a business plan for the selenium nanoparticle coatings while in school and have since licensed the technology from Brown for their company, Axena Technologies.

The Hermann Foundation funded the research.


Story Source:

The above story is based on materials provided by Brown University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Qi Wang, Thomas J. Webster. Nanostructured selenium for preventing biofilm formation on polycarbonate medical devices. Journal of Biomedical Materials Research Part A, 2012; DOI: 10.1002/jbm.a.34262

Cite This Page:

Brown University. "Selenium suppresses staph on implant material." ScienceDaily. ScienceDaily, 21 June 2012. <www.sciencedaily.com/releases/2012/06/120621113345.htm>.
Brown University. (2012, June 21). Selenium suppresses staph on implant material. ScienceDaily. Retrieved August 1, 2014 from www.sciencedaily.com/releases/2012/06/120621113345.htm
Brown University. "Selenium suppresses staph on implant material." ScienceDaily. www.sciencedaily.com/releases/2012/06/120621113345.htm (accessed August 1, 2014).

Share This




More Plants & Animals News

Friday, August 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Florida Panther Rebound Upsets Ranchers

Florida Panther Rebound Upsets Ranchers

AP (July 31, 2014) With Florida's panther population rebounding, some ranchers complain the protected predators are once again killing their calves. (July 31) Video provided by AP
Powered by NewsLook.com
Dangerous Bacteria Kills One in Florida

Dangerous Bacteria Kills One in Florida

AP (July 31, 2014) Sarasota County, Florida health officials have issued a warning against eating raw oysters and exposing open wounds to coastal and inland waters after a dangerous bacteria killed one person and made another sick. (July 31) Video provided by AP
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
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