Bioinspired bright noniridescent photonic melanin supraballs

• Published in: Science advances Vol. 3; no. 9; p. e1701151
• Main Authors: Xiao, Ming, Hu, Ziying, Wang, Zhao, Li, Yiwen, Tormo, Alejandro Diaz, Le Thomas, Nicolas, Wang, Boxiang, Gianneschi, Nathan C, Shawkey, Matthew D, Dhinojwala, Ali
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 01.09.2017
• Subjects: Applied Sciences and Engineering; Photonics; SciAdv r-articles
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.1701151

Structural colors enable the creation of a spectrum of nonfading colors without pigments, potentially replacing toxic metal oxides and conjugated organic pigments. However, significant challenges remain to achieve the contrast needed for a complete gamut of colors and a scalable process for industrial application. We demonstrate a feasible solution for producing structural colors inspired by bird feathers. We have designed core-shell nanoparticles using high-refractive index (RI) (~1.74) melanin cores and low-RI (~1.45) silica shells. The design of these nanoparticles was guided by finite-difference time-domain simulations. These nanoparticles were self-assembled using a one-pot reverse emulsion process, which resulted in bright and noniridescent supraballs. With the combination of only two ingredients, synthetic melanin and silica, we can generate a full spectrum of colors. These supraballs could be directly added to paints, plastics, and coatings and also used as ultraviolet-resistant inks or cosmetics.