Wash-off cream could prevent nickel allergy, study suggests

A team of Harvard researchers may have discovered a new way to ward off the red, itchy rash caused by allergies to nickel.  All it takes is a dab of topical cream, according to research published online Sunday in the journal Nature Nanotechnology.

Thirty million to 45 million people -- more than 10% of the U.S. population -- are sensitive to nickel found in common objects including jewelry and coins, the paper reported. 

Among the sufferers: study lead author Jeffrey M. Karp of Harvard's Brigham and Women's Hospital in Boston, a nanoparticles specialist who sought a way to treat the irritating allergy.

The key, he and his coauthors hypothesized?  Using nanoparticles that could bind with the nickel ions that rub off of jewelry and other objects, enter the skin and wreak havoc. The nanoparticles would have to be small enough to efficiently capture the nickel (less than 500 nanometers) but large enough that they couldn't penetrate the skin themselves (larger than 20 nanometers in diameter).

The scientists mixed nanoparticles of calcium carbonate and calcium phosphate of diameter around 70 nanometers -- which are "generally recognized as safe" by the Food and Drug Administration -- into a glycerin emollient. They then applied the cream to the skin of pigs (in a laboratory dish) and onto live mice.  Calcium compounds are known to bind with nickel -- and these nanoparticles successfully captured nickel ions, the team found.  Nickel-sensitive mice treated with the cream had less inflammation than did mice treated with glycerine only.  

Once the nanoparticles captured the nickel ions, the lotion and nickel could be washed off with water, the team reported. 

Thus far, people with nickel allergies have had to make do with avoiding the metal or painting their jewelry with nail polish to create a barrier between the nickel and their skin.  While researchers have tried to develop chemical agents to bind to the nickel, these haven't worked particularly well and in some cases have been toxic, Karp said in a statement.

No one should rush out to stock up on nickel-laden costume jewelry just yet -- the nanoparticle cream hasn't been approved for use by people.  But the research team seems to think the lotion has a lot of potential. It already has a patent on the work.

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