Progress in polydopamine-based melanin mimetic materials for structural color generation

Abstract

Structural color is a color derived from optical interaction between light and a microstructure and is often seen in nature. Natural melanin plays an important role in bright structural coloration. For example, the vivid colors of peacock feathers are due to structural colors. The periodic arrangement of melanin granules inside the feathers leads to light interference, and the black granules absorb scattered light well, resulting in bright structural color. In recent years, polydopamine (PDA) has attracted attention as a melanin mimetic material. This review article summarizes recent research on structural coloration using PDAbased artificial melanin materials. It also outlines possible applications using bright structural colors realized by artificial melanin materials and future perspectives.

Melanin, the What, the Why and the How: An Introductory Review for Materials Scientists Interested in Flexible and Versatile Polymers

“…For recent, in-depth reviews about this structural colorant approach to using melanin, Xiao et al and Kohri et al are highly recommended [76,134]. These authors also discuss the optical properties of melanins as well as applications including UV protection agents, fluorescent probes and photothermal therapy and as such will not be reviewed here.…”

Optimization of extractions of eumelanin from cuttlefish ink and the hypoglycemic effects: In vitro enzyme inhibitory activity and glucose consumption in HepG2 cells

“…Removal of protein can effectively purify eumelanin. The presence of eumelanin is also essential for the structural color of organisms characterized by bright colors (Kohri, 2020). Melanin is also a compelling material for photonic applications because of its favorable material characteristics (Xiao et al, 2020).…”

Melanin-based structural coloration of birds and its biomimetic applications

“…However, artificial melanin-based structural colors do not need to add extra absorbing materials, because artificial melanin can absorb broadband light and form nanostructures. As PDA can be synthesized in various forms from thin films to core-shell particles, many researchers have used PDA to produce structural colors (Kohri 2019 , 2020 ; Xiao et al 2020 ). Self-assembly of colloidal nanoparticles is one of the important and effective methods to produce structural colors.…”

“…Traditional and more recent technologies, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), electron energy loss spectroscopy (EELS), and energy-dispersive spectroscopy (EDS) have enabled huge advances in understanding the molecular structures, optical properties, and coloration mechanisms in the last few decades (Galeb et al 2021 ). Over the last decade, several papers have reviewed melanin chemistry, optical functions of melanin, melanosome morphology, and biomimetic structural coloration (D'Alba and Shawkey 2019 ; Kohri 2019 , 2020 ; Sun et al 2013 ; Xiao et al 2020 ). However, there is a lack of a comprehensive review focusing on how optical and structural properties of melanin are related to biomimetic applications.…”