A permanent solution! Scientists, for the first time, have synthesised gold nanoparticles for dyeing white hair to near permanent brown shades.
The process involves soaking white hair in a solution of a gold compound, turning them pale yellow and then darkening them to a deep brown.
Using an electron microscope, French scientists confirmed that the particles were forming inside the central core cortex of the hair. The colour remained even after repeated washings.
Scientists reported the discovery had applications ranging from hair dyeing to electronic sensors to development of materials with improved properties.
Philippe Walter, director of a lab at the Centre National de la Recherche Scientifique (CNRS) 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 other uses, ranging from electronics and sensors to medical diagnostic tests and cancer treatments, the American Chemical Society (ACS) reported.
Gold nanoparticles have been deposited on hair for use as electrodes, and also 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 colour their hair.
The study was published in American Chemical Society ACS' journal Nano Letters.