US researchers develop new solution for structural colours

Researchers from the University of Akron in the US have developed a way to produce a non-fading product colour.

Most product colours around us incorporate paints and dyes that absorb certain wavelengths of light and reflect the remaining. In contrast, structural colours use an object’s nanostructure to amplify a particular wavelength and produce colour.

Formulated in collaboration with researchers from Northwestern University and Belgium-based University of Ghent, the structural colours solution is expected to be applicable to various industries, including cosmetics.

Researchers designed core-shell synthetic melanin nanoparticles, which have the potential to replace toxic metal oxides and organic pigments. This work is based on previous research on melanin, where it was observed that upon loading into semi-ordered spherical particles, small synthetic melanin packets generated structural colour.

When self-assembled with a one-pot reverse emulsion process, the nanoparticles are reported to form bright and non-iridescent supraballs.

University of Akron's postdoctoral research fellow Ming Xiao said: “The use of melanin as the core material can increase the brightness and saturation of supraballs due to its unique combination of high resonance imaging (RI) and broad band absorption of light.

“In addition, melanin is biocompatible and can dissipate almost 90% of the ultraviolet (UV) radiation into heat within a nanosecond, making those melanin-based supraballs suitable for cosmetics or UV-resistant inks.”

The new solution is expected to address concerns with existing structural colours that are iridescent and not applicable for wide-angle displays or non-iridescents without colour saturation.

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Image: The pigments in these supraballs can be used in everything from clothing and paint to cosmetics. Photo: courtesy of The University of Akron.