A study conducted French scientist, Dr Philippe Walter and his
team, published in ACS Nano Letters, found that hair could
synthesize gold nanoparticles into the hair cuticle. It is
understood that 40,000-60,000 gold nanoparticles could fit
across the width of a human hair. The original aim of the study
was to look at the structure of keratin within hair, and how
keratin breaks down, with gold nanoparticles used as a tracking
substance within the subject. The team soaked white hairs in a
solution of a gold compound, and the hairs turned pale yellow
and then darkened to a deep brown. Using an electron microscope,
the scientists confirmed that the particles were forming inside
the hairs’ central core cortex, and that colour remained even
after repeated washings. Walter noted that after the hair was
exposed to the gold, it was synthesized into the hair, which is
a normal process for a hair dye. However, in this instance the
gold nanoparticles remained, suggesting there could be
implications for permanent hair col