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...
Let's start with an introduction about Nanowerk . This is the home of the Nanomaterial Database, a "tool for the nanotechnology community to research and buy nanomaterials from many suppliers worldwide" which currently contains 1,321 nanoparticles from 91 suppliers.
Now, let's move to the recent Nanowerk news release about the use of nanocosmetics in Ancient Egypt and elsewhere. Nanowerk talked to Dr. Philippe Walter from the Centre de recherche et de restauration des musées de France (C2RMF) in Paris.
"For thousands of years, cosmetics have been used and were made by the judicious combination of naturally available minerals with oils, various creams, or water. Since the Greco-Roman period, organic hair dyes obtained from plants such as henna have been used, but other unusual formulas based on lead compounds, such as the recipes describing several methods to dye hair and wool black, were also common. It is remarkable that these Greco-Roman techniques have been used up to modern times."
In recent experiments, Walter and his colleagues "showed that an ancient dyeing process for blacking hair is a remarkable illustration of synthetic nanoscale biomineralization." As an example, you can see on the right three microphotographs of hair transverse cross sections (thickness is about 10 micrometers). From top to bottom, the images show the "progressive blackening during treatment with lime and lead oxide in water" (top: no treatment; middle: after 6 hours; bottom: after 72 hours). (Credit: American Chemical Society's Nano Letters)
Here are some more explanations about the hair structure and how it was affected by these dyes.
The hair shaft contains three principal concentric histological regions: the cuticle, the cortex, and the medulla. The researchers found the presence of PbS particles in the cuticle and the cortex, which modifies the optical aspect of the hair shaft irreversibly. Nevertheless, the hair mechanical properties are essentially unaffected because of the extremely small size and volume fraction of the crystals. This opened the application of the dye formula for 2000 years.
For their experiments, the researchers used "an ancient lead-based recipe to dye hair black."
They found that the treated hair showed the presence of galena nanocrystals with an average diameter of under 5 nm. Natural black hair color is due to melanin clusters of ca. 300 nm dispersed within the colorless keratin-based cortex of hair. Lead-based hair-dying chemicals generate a kind of melanin substitute produced by synthesis of PbS inside hair; but these blackening PbS particles are much smaller than melanin clusters by 4-5 orders of magnitude in volume.
For more information about the use of cosmetics based on lead in the Antiquity, here are some interesting places to visit:
So, if nanoparticles were used 4,000 years ago without hurting the Egyptian kings and queens, you can expect to see more and more cosmetics using nanotechnology.
Sources: Michael Berger, Nanowerk LLC news release, September 5, 2006; and various web sites
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