Gold nanoparticles can make your hair brown

The Jan. 2, 2013 news item on Nanowerk notes that scientists have been able to synthesize gold nanoparticles inside human hair (Note: A link has been removed),

In a discovery with applications ranging from hair dyeing to electronic sensors to development of materials with improved properties, scientists are reporting the first synthesis of gold nanoparticles inside human hairs. Their study appears in ACS’ journal Nano Letters (“Hair Fiber as a Nanoreactor in Controlled Synthesis of Fluorescent Gold Nanoparticles”).

The Jan. 2, 2012 press release from the American Chemical Society (ACS), which originated the news item, provides a few more details,

Philippe Walter and colleagues explain that gold nanoparticles — 40,000-60,000 of which could fit across the width of a human hair — are a hot topic. Scientists are exploring uses, ranging from electronics and sensors to medical diagnostic tests and cancer treatments. Gold nanoparticles have been deposited on hair for use as electrodes, and gold nanoparticles had been used to dye wool. Walter’s team looked at a new use — dyeing hair, inspired by the ancient Greeks’ and Romans’ use of another metal, lead, to color their hair.

They describe the first synthesis of fluorescent gold nanoparticles inside human hair. It involved soaking white hairs in a solution of a gold compound. 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. The color remained even after repeated washings.

The authors acknowledge funding from the Agence Nationale de la Recherche.

Here’s what the hair looks like,

Gold nanoparticles darken hair after treatment for one day, center, and 16 days, right (untreated hairs, left). Credit: American Chemical Society

Gold nanoparticles darken hair after treatment
for one day, center, and 16 days, right
(untreated hairs, left).
Credit: American Chemical Society

For anyone who wants to follow up further, there’s a citation for and link to the research paper,

Hair Fiber as a Nanoreactor in Controlled Synthesis of Fluorescent Gold Nanoparticles by Shrutisagar D. Haveli, Philippe Walter, Gilles Patriarche, Jeanne Ayache, Jacques Castaing, Elsa Van Elslande, Georges Tsoucaris, Ping-An Wang, and Henri B. Kagan in Nano Lett., 2012, 12 (12), pp. 6212-5217 DOI: 10.1021/nl303107w Publication Date (Web): Nov. 2, 2012 © 2012 American Chemical Society

This is paper is behind a paywall.

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