Feather-inspired nanomaterials create color with light

Chuck Bednar for redOrbit.com – @BednarChuck

Drawing inspiration from the way physical structure, not pigments, determines the colors of bird feathers, a team of researchers has developed a type of nanomaterial capable of reflecting the pure colors of light based on their thickness and density.

As they explain in a recent edition of the journal ACS Nano, University of California, San Diego chemistry and biochemistry professor Nathan Gianneschi and colleagues studied the way structural colors arise from the way that bird feathers interact with light. They then adapted that data to create thin films of material that can come in a wide range of different hues.

In a statement, Gianneschi explained that his team synthesized and assembled nanoscale-sized particles of a synthetic version of melanin in order to mimic the structures naturally found in a bird’s feathers. Their goal was to understand how materials like these were used in nature, then develop new functions that exceed those found in the natural world.

“The research is inspired by the fact that birds and other organisms use nanoscale particles and features to produce spectacular displays of color,” the professor told redOrbit via email. “When I learned that bird feathers contained nanoscale particles of melanin, we became interested in whether we could synthesize mimics of those particles in the laboratory.”

Linking dopamine molecules to form synthetic melanin

The researchers explained that structural colors play a role in many different types of biological functions, including camouflage and sexual signaling. This phenomenon is a result of the interaction of light with materials that possess small-scale patterns, bending and reflecting light to amplify some wavelengths and dampen others.

Bird feathers, as well as the skin and fur of many other types of animals, contain tiny packets of melanin known as melanosomes that produce structural color when packed into solid layers, the researchers explained. Gianneschi’s team set out to create and assemble synthetic polydopamine-based melanin nanoparticles in an attempt to fabricate these colored films.

They created their nanoparticles by linking a similar molecule (dopamine) into meshes, forming it into spherical particles of similar sizes and experimenting with different concentrations to form thin films of tightly packed, linked dopamine particles. These films were found to reflect the pure colors of light (red, orange, yellow, and green) at different times depending upon the thickness of the layers and how tightly the particles were packed together.

Future potential and uses

Precise measurements showed that the hues were exceptionally uniform in nature, and according to Gianneschi, there are many potential applications for this technology, such as colorimetric sensors, paints and dyes that will not fade like their pigment-based counterparts, and protective coatings that can be used to absorb ultraviolet light.

“The broad absorption, and high refractive index of the melanin-like materials that we made, open up new possibilities for the development of scalable nanostructures capable of generating colors not dependent on pigments,” the professor explained to redOrbit via email.

In the long term, he said, these types of materials could provide not just colors that are fade-resistant, but could even be capable of changing as surfaces sense changes to their environment. Just as chameleons adapt and change colors in this way, we are learning how to build complex colors on active surfaces that could enable the development of synthetic materials and devices capable of similar types of displays, Gianneschi added.

“The ability to control the size and shape of nanoparticles made from polymers (so called, soft nanomaterials) promises to open up doors for the development of functional materials,” he told redOrbit. “These are the types of materials used by nature, with viruses and all sorts of other nanoscale compartments being incredibly prevalent in biology.”

“We take inspiration from the fact that biological systems are able to perform precision synthesis to generate these types of materials,” Gianneschi concluded. “However, by comparison, synthetic chemistry is far, far behind. Continued work is needed to fulfill the promise of such systems.”

—–

Follow redOrbit on Twitter, Facebook, Google+, Instagram and Pinterest.

redOrbit.com
offers Science, Space, Technology, Health news, videos, images and
reference information. For the latest science news, space news,
technology news, health news visit redOrbit.com frequently. Learn
something new every day.”

Source: http://www.redorbit.com/news/science/1113391108/feather-inspired-nanomaterials-create-color-with-light-051415/