Wu Tong-Fei, Hong Jong-Dal
Department of Chemistry, Research Institute of Natural Sciences, Incheon National University , 119 Academy-ro, Yeonsu-gu, Incheon 406-772, Republic of Korea.
Biomacromolecules. 2015 Feb 9;16(2):660-6. doi: 10.1021/bm501773c. Epub 2015 Jan 23.
This 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.
本文描述了在静态条件下，多巴胺 - 黑色素薄膜（厚度为50 - 200纳米）在空气/多巴胺溶液界面的形成过程。在这些薄膜下方，球形黑色素颗粒在本体液相中形成。界面处多巴胺 - 黑色素薄膜的厚度主要取决于多巴胺溶液的浓度和反应时间。基于多巴胺 - 黑色素聚集体的疏水性以及对流导致聚集体向空气/溶液界面的质量传输，提出了一种解释多巴胺 - 黑色素薄膜形成的合理机制。界面薄膜的厚度随多巴胺浓度和反应时间呈线性增加。具有双层结构的多巴胺 - 黑色素薄膜和颗粒（在本体液相中形成）被转移到固体基板上，以模拟鸟类羽毛中存在的（角质层）/（黑色素颗粒）结构，从而制备出完整的多巴胺 - 黑色素薄膜反射器。薄膜反射器的反射颜色取决于薄膜厚度，而薄膜厚度可根据多巴胺浓度进行调节。所得反射器的反射率呈现出8 - 11%的最大反射率值，与鸟类羽毛的反射率（约11%）相当。本研究提供了一种使用全多巴胺 - 黑色素材料制造仿生薄膜反射器的有用、简单且低成本的方法。
