Nanoparticles reduce nickel allergy by capturing metal ions

TLDR: It is shown that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin and on the skin of mice prevents the penetration of nickel ions into the skin.

Abstract: Approximately 10% of the population in the USA1,2 suffer from nickel allergy3,4,5, and many are unable to wear jewellery or handle coins and other objects that contain nickel6,7,8,9,10. Many agents have been developed to reduce the penetration of nickel through skin11,12, but few formulations are safe and effective13,14,15. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may be an effective way to limit the exposure to metal ions that can cause skin irritation. Applying an emollient containing calcium carbonate or calcium phosphate nanoparticles can reduce skin exposure to nickel ions that cause skin allergy.