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nanotimes News in Brief
Researchers at Brigham and Women‘s Hospital (BWH) have found that nanoparticles containing calcium could offer a safe solution to the allergic problem of nickel. These nanoparticles could pre- vent the itchy, red rash millions suffer from because they are allergic to the nickel found in many every- day objects.
“There have been approaches to developing creams with agents that bind the nickel before it can pe- netrate the skin, but these are not effective in most patients and can even be toxic when the agents themselves penetrate the skin, as most do,” says Jeffrey Karp, leader of the work and co-director of the Center for Regenerative Therapeutics at BWH. He adds, “People also sometimes coat their jewelry with nail polish to create a barrier between the skin and nickel ions, but this won’t prevent all expo- sures, such as handling coins or wearing a watch.”
When applied to the skin in a cream, the nanoparti- cles efficiently capture the nickel, preventing it from making its way into the body. Further, the nanopar- ticles themselves were designed so that they cannot penetrate the skin. The cream with its nickel can then be easily washed off with water.
R. Rox Anderson, a dermatologist at Harvard Me- dical School and Massachusetts General Hospital, says: “Despite barrier creams, anti-inflammatory drugs, and attempts to avoid nickel, this [metal] is still the most common cause of allergic skin reac- tions. Nanoparticles that bind to [the nickel] all- ergens but do not penetrate the skin offer a new strategy. Big hope in a small package!” “We expect that a person could simply apply the cream just as they would hand cream,” says Pra-
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veen Kumar Vemula of BWH, HMS, HSCI, and HST. Vemula is first author of the paper. The team limited their search to nanoparticles within a certain size range. “We wanted them to be large enough so they could not penetrate the skin, yet small enough to present a very large surface area for capturing nickel,” Vemula says. (They ultimately decided on particles between 70 and 500nm.) Finally, to cut the time involved in bringing a new technology to market, the team only explored nanoparticles alrea- dy designated by the Food and Drug Administration as being generally recognized as safe (GRAS) for use in humans.
They found two compounds that met these criteria (calcium carbonate and calcium phosphate), added them to a common emollient to create a cream, and tested them under a variety of experimental conditions.
“We were able to demonstrate that the particles could indeed capture nickel with high efficien- cy and prevent inflammation in nickel-sensitized animals,” Karp says. Further, “we needed 11-fold less nanoparticles to get the same effect” as another common nickel-capture agent. (A significant draw- back of the latter: it can penetrate the skin, and even small amounts can cause local and systemic toxicity.)
Praveen Kumar Vemula, R. Rox Anderson & Jeffrey M. Karp: Nanoparticles reduce nickel allergy by capturing metal ions, In: Nature Nanotechnology, Volume 6(2011), No 5, May 2011, Pages 291-295, DOI:10.1038/nna- no.2011.37: