How to lose 50 years of aging in 16 days

January 3, 2013

Gold nanoparticles darken white hair after treatment for one day, center, and 16 days, right (credit: American Chemical Society)

Attention seniors: French scientists have developed a process that permanently dyes white hair without harmful chemicals.

Philippe Walter and colleagues soaked white hairs in a solution containing fluorescent gold nanoparticles.

The hairs turned pale yellow and then darkened to a deep brown. The color remained even after repeated washings.

Using an electron microscope, the scientists confirmed that the particles were forming inside the hairs’ central core cortex.

The discovery has applications ranging from hair dyeing to electronic sensors to development of materials with improved properties, the scientists said.

The synthesis and detailed characterization of gold nanoparticles (AuNPs) inside human hair has been achieved by treatment of hair with HAuCl4 in alkaline medium. The AuNPs, which show a strong red fluorescence under blue light, are generated inside the fiber and are arranged in the cortex in a remarkably regular pattern of whorls based on concentric circles, like a fingerprint. It opens an area of genuine nanocomposites with novel properties due to AuNPs inside the hair shaft. (Credit: American Chemical Society)