Selective Coloration of Melanin Nanospheres through Resonant Mie Scattering

Cho, Soojeong; Shim, Tae Soup; Kim, Ju Hyeon; Kim, Dong Hyun; Kim, Shin‐Hyun

doi:10.1002/adma.201700256

Cited by 62 publications

(45 citation statements)

References 24 publications

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“…These disordered elements in the ordered HNFs result in removal of the directionality, which is essential for a noniridescent color reflector, as found in a morpho butterfly 19 . This phenomenon is comparable to the case of the close-packed structure-based color reflectors such as photonic crystals comprising colloidal particles 20,21 .…”

Section: Optical Properties Of the Fabricated Structural Color Reflecsupporting

confidence: 54%

Directed self-assembly of a helical nanofilament liquid crystal phase for use as structural color reflectors

Park

Kim

et al. 2019

NPG Asia Mater

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The fabrication of molecular structures with a desired morphology, e.g., nanotubes, nanoribbons, nanosprings, and sponges, is essential for the advancement of nanotechnology. Unfortunately, realization of this objective is expensive and complicated. Here, we report that irradiating a film comprising azobenzene derivatives with UV light produces oriented arrays of helical nanofilaments via the photoisomerization-induced Weigert effect. As a result, structural colors are observed due to the extrinsic chiral reflection in the visible wavelength range, and the reflected color can be tuned by adjusting the molecular length of the azobenzene derivative. This simple fabrication method can be used for fabricating large, reversible, and patternable color reflectors, providing a new platform for interference-based structural coloration as it exists in nature, such as morpho butterflies, green-winged teal, and various beetles.

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Section: Optical Properties Of the Fabricated Structural Color Reflecsupporting

confidence: 54%

Directed self-assembly of a helical nanofilament liquid crystal phase for use as structural color reflectors

Park

Kim

et al. 2019

NPG Asia Mater

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“…As the concentration decreases from 1 to 0.01 wt% for the 307‐nm nanospheres in ethanol, we see that the suspensions become more translucent, but the color remains, albeit weaker in intensity ( Figure e). We expect no structural correlations at such low concentrations, though we do expect the reflectance peaks to red‐shift owing to the different refractive index of the medium . Indeed, single‐scattering calculations of the nanospheres in ethanol again agree with the measured reflectance peaks (Figure c).…”

supporting

confidence: 54%

“…An alternative approach is to rely on the wavelength‐dependent scattering of the particles themselves. Cho et al demonstrated that colloidal particles of light‐absorbing melanin show colors due to Mie resonances. The melanin or polydopamine in the particles suppresses multiple scattering owing to its strong absorption, but the colors are visible only under intense directional illumination.…”

mentioning

confidence: 99%

“…We make the films by mixing the particles with a polymeric binder and a drying solvent (see Methods in Supporting Information). The color and saturation of the films can be controlled by adjusting the particle diameter, refractive index, and concentration in the film . We choose poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) as the polymeric binder for the composite films because its refractive index (≈1.407) is higher than that of water but close to that of silica, so that the transport length of light can be even longer.…”

mentioning

confidence: 99%

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Solution‐Processable Photonic Inks of Mie‐Resonant Hollow Carbon–Silica Nanospheres

Kim

Hwang

Lee

et al. 2019

Small

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Whereas ordinary color comes from selective absorption by pigments or dyes, [1,2] structural color comes from coherent scattering from nanostructures. [3,4] However, ordered nanostructures lead to structural color that depends strongly on the viewing angle, which limits its practical applications. By contrast, materials with short-range order, such as colloidal glasses [5][6][7][8] or blue bird feathers, [9][10][11][12][13] show structural color that is independent of angle. While these materials could in principle be used in applications that require structural color that is indistinguishable from pigment, they also tend to diffuse or multiply scatter light, leading to colors that are not saturated. The multiple scattering can be suppressed by dyes such as carbon black.An alternative approach is to rely on the wavelengthdependent scattering of the particles themselves. Cho et al. [14] Hollow carbon-silica nanospheres that exhibit angle-independent structural color with high saturation and minimal absorption are made. Through scattering calculations, it is shown that the structural color arises from Mie resonances that are tuned precisely by varying the thickness of the shells. Since the color does not depend on the spatial arrangement of the particles, the coloration is angle independent and vibrant in powders and liquid suspensions. These properties make hollow carbon-silica nanospheres ideal for applications, and their potential in making flexible, angle-independent films and 3D printed films is explored. Photonic Inks

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“…It is well known that melanin in human hair exists in the form of melanin granules, which was reported to contain plenty of functional groups such as amino, carboxyl, and indolyl groups (Cho et al, 2017;Mostert et al, 2018;D'Ischia et al, 2014). In our previous study, natural melanin particles (NMPs) were extracted from human hair by using alkaline-degradation method, also confirming the presence of functional groups (Zheng et al, 2018).…”

Section: Introductionmentioning

confidence: 62%

Enzyme Mimicking Based on the Natural Melanin Particles from Human Hair

Hong¹,

Zhang²,

Zheng³

et al. 2020

iScience

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Natural enzymes are mainly composed by the protein part and metallic cofactor part, both of which work cooperatively to achieve high catalytic activity. Here, natural melanin particles (NMPs) were extracted from human hair and further bound with metal ions to mimic natural enzymes. The different metal-bound NMPs (M-NMPs) exhibited different enzyme-like activities with great promise in diverse biomedical applications. It was found that Fe-bound NMPs (Fe-NMPs) showed outstanding peroxidase (POD)-like activity that possessed potential in antibacterial applications, and Mn-bound NMPs (Mn-NMPs) displayed catalase (CAT)-like activity with a remarkable radiotherapy sensitization effect in cancer therapy. Besides, Cu-bound NMPs (Cu-NMPs) could serve as combined POD, superoxide dismutase (SOD), and CAT alternatives, which exhibited prominent reactive oxygen species (ROS) scavenging ability, revealing great potential in anti-inflammation. The versatile enzyme-like activities of M-NMPs derived from hair might give extensive perspective for designing biomedical materials and provide a promising tool in solving biomedical problems.

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Selective Coloration of Melanin Nanospheres through Resonant Mie Scattering

Cited by 62 publications

References 24 publications

Directed self-assembly of a helical nanofilament liquid crystal phase for use as structural color reflectors

Directed self-assembly of a helical nanofilament liquid crystal phase for use as structural color reflectors

Solution‐Processable Photonic Inks of Mie‐Resonant Hollow Carbon–Silica Nanospheres

Enzyme Mimicking Based on the Natural Melanin Particles from Human Hair

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