Selective Coloration of Melanin Nanospheres through Resonant Mie Scattering

Black melanin inks are prepared to selectively exhibit colors under strong light, inspired by human hair. High absorbance of melanin suppresses multiple scattering, causing resonant Mie scattering predominant. Various colors can be developed as the resonant wavelength dictated by nanosphere diameter. Therefore, the melanin inks can be used to encrypt and selectively disclose multicolor patterns for anticounterfeiting applications.