Gold nanoparticles have been successfully used to dye white hair a deep brown colour, according to a study published in the journal Nano Letters.
In addition to altering the colour, the particles -- around 40,000 to 60,000 times smaller than the width of a human hair -- also caused the dyed locks to fluoresce an intense red under blue light.
The colour change was created by soaking white hairs in a solution made from the gold compound chloroauric acid, calcium hydroxide and distilled water. The resulting shades appear fade resistant as gold's affinity for the sulphur-containing amino acids found in keratin means the nanoparticles are buried and stabilised inside the hair, remaining unaffected by repeated washings.
But, while the dye potential of nanoparticles has now been demonstrated, the process isn't likely to make it to a salon for a while yet -- white hair took a magazine-intensive seven hours to begin to pick up a pale yellow hue, while the dark brown took an epic Russian novel-friendly 16 days to develop.
According to the research, which was funded by the French National Centre for Scientific Research (CNRS), the nanoparticle-infused hair also has applications beyond the obvious.
The red fluorescence could even give the hairs the potential to function as microsensors for metal salts.
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This article was originally published by WIRED UK
