Nanoparticle Used in Ancient Egypt

Egyptians used a Lead-based nanoparticle to dye hair. French researchers (who else?) found this:

French researchers have found that Egyptians, Greek and Romans were using nanotechnology to dye their hair several thousands years ago. In "Nanotechnology in Cosmetics - 2000 Years Ago...," Nanowerk Spotlight reports they were using lead compounds which generated lead sulfide (PbS) nanocrystals with a diameter of only 5 nanometers. At a moment where many people wonder if the use of nanoparticles is safe, it's good to know that nanotechnology has been widely used for a very long time. But read more...