bm501773c_si_001.pdf (518.35 kB)
Dopamine-Melanin Nanofilms for Biomimetic Structural Coloration
journal contribution
posted on 2015-02-09, 00:00 authored by Tong-Fei Wu, Jong-Dal HongThis article describes the formation
of dopamine-melanin thin films
(50–200 nm thick) at an air/dopamine solution interface under
static conditions. Beneath these films, spherical melanin granules
formed in bulk liquid phase. The thickness of dopamine-melanin films
at the interface relied mainly on the concentration of dopamine solution
and the reaction time. A plausible mechanism underlining dopamine-melanin
thin film formation was proposed based on the hydrophobicity of dopamine-melanin
aggregates and the mass transport of the aggregates to the air/solution
interface as a result of convective flow. The thickness of the interfacial
films increased linearly with the dopamine concentration and the reaction
time. The dopamine-melanin thin film and granules (formed in bulk
liquid phase) with a double-layered structure were transferred onto
a solid substrate to mimic the (keratin layer)/(melanin granules)
structure present in bird plumage, thereby preparing full dopamine-melanin
thin-film reflectors. The reflected color of the thin-film reflectors
depended on the film thickness, which could be adjusted according
to the dopamine concentration. The reflectance of the resulted reflectors
exhibited a maximal reflectance value of 8–11%, comparable
to that of bird plumage (∼11%). This study provides a useful,
simple, and low-cost approach to the fabrication of biomimetic thin-film
reflectors using full dopamine-melanin materials.