8/3/2019 Nanotechnology in Cosmetics

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Section: HIDDEN TECHNOLOGIES IN VEDAS AND HISTORY

--Aashrith Parvathaneni

Nanotechnology in cosmetics - 2000 years ago...?

(Nanowerk Spotlight ) These days we are debating if nanoparticles in sunblock and toothpaste are safe.The ancient Greeks and Romans didn't know about such things - but they already used nanotechnologyin their cosmetics. A group of researchers in France showed that lead-based chemistry, which was

initiated in Egypt more than 4000 years ago, could result in the synthesis of lead sulfide (PbS, galena)nanocrystals. With a diameter of about 5 nm, the appearance of these crystals is quite similar to PbSquantum dots synthesized by modern materials science techniques.

Dr. Philippe Walter from the Centre de recherche et de restauration des musées de France(C2RMF-CNRS) in Paris explained these recent findings to Nanowerk: "For thousands of years, cosmetics havebeen used and were made by the judicious combination of naturally available minerals with oils, variouscreams, or water. Since the Greco-Roman period, organic hair dyes obtained from plants such as hennahave been used, but other unusual formulas based on lead compounds, such as the recipes describingseveral methods to dye hair and wool black, were also common. It is remarkable that these Greco-Romantechniques have been used up to modern times."

Walter, a Senior Research Scientist at the C2RMF-CNRS and head of the AGLAE and analyticalchemistry goup, together with colleagues from the Laboratoire d'étude des microstructures from the

French national aerospace research center and L'Oréal Research in France, as well as Argonne NationalLaboratory in the U.S., showed that an ancient dyeing process for blacking hair is a remarkableillustration of synthetic nanoscale biomineralization.

"In contrast to modern nanotechnology, the dyeing process is characterized by basic chemistry methodsand has been developed more than 2000 years ago with low-cost natural materials" Walter points out.

The hair shaft contains three principal concentric histological regions: the cuticle, the cortex, and themedulla. The researchers found the presence of PbS particles in the cuticle and the cortex, whichmodifies the optical aspect of the hair shaft irreversibly. Nevertheless, the hair mechanical properties areessentially unaffected because of the extremely small size and volume fraction of the crystals. Thisopened the application of the dye formula for 2000 years.

"What is particularly surprising in this reaction" says Walter, "is that, despite the structural complexity of hair and its relative chemical inertness, metal sulfide nanoparticles easily crystallize and get organizedinside this biomaterial, i.e. in the hair shaft. It seems that sulfur-rich peptides in the matrix surroundingsupramolecular- organized keratin proteins serve as nanoscale reactors."

8/3/2019 Nanotechnology in Cosmetics

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Section: HIDDEN TECHNOLOGIES IN VEDAS AND HISTORY

--Aashrith Parvathaneni

O ptical macrophotographs of hair (A-C) and microphotographs (D-F) of the corresponding transverse

cross sections (thickness ) 10 ím), showing progressive blackening during treatment with lime and lead oxide in water (25 °C, pH ) 12.5). (A and D) nontreated, (B and E) 6h, (C and F) 72h. (reprinted with

 permission from American Chemical Society) 

For their experiments, which are described in a recent paper in Nano Letters ("Early Use of PbSNanotechnology for an Ancient Hair Dyeing Formula"), the researchers used an ancient lead-basedrecipe to dye hair black. They found that the treated hair showed the presence of galena nanocrystalswith 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 bysynthesis of PbS inside hair; but these blackening PbS particles are much smaller than melanin clustersby 4-5 orders of magnitude in volume.

With research like this, the scientists hope to better control the conditions for growth and organization of nanoparticles in organic matrix which ultimately could open new perspectives in the development of nanocomposites.