Control of Structural Coloration by Natural Sunlight Irradiation on a Melanin Precursor Polymer Inspired by Skin Tanning

Okoshi, Taku; Iwasaki, Takeshi; Takahashi, Shimon; Iwasaki, Yasuhiko; Kishikawa, Keiki; Kohri, Michinari

doi:10.1021/acs.biomac.1c00161

Cited by 9 publications

(11 citation statements)

References 63 publications

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“…Both DA-coated and MDA-coated stretching modes, respectively (Figure S2). 26,27 However, these peaks were not observed from the DMDA-coated Ti/TiO 2 surfaces. The results indicated that DA and MDA coatings proceeded through intramolecular cyclization (Figure S3).…”

Section: ■ Results and Discussionmentioning

confidence: 93%

“…Both DA-coated and MDA-coated surfaces showed characteristic peaks at 1600, 1510, 1350, and 1250 cm –1 , corresponding to ν ring (CC) stretching, ν ring (CN) stretching, ν indole (CNC) stretching, and ν(C–O)/ν(C–N) stretching modes, respectively (Figure S2). , However, these peaks were not observed from the DMDA-coated Ti/TiO 2 surfaces. The results indicated that DA and MDA coatings proceeded through intramolecular cyclization (Figure S3).…”

Section: Resultsmentioning

confidence: 99%

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Effect of N-Methylation on Dopamine Surface Chemistry

et al. 2022

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Dopamine (DA) surface chemistry has received significant attention because of its applicability in a wide range of research fields and the ability to graft functional molecules onto numerous solid surfaces. Various DA derivatives have been newly synthesized to identify key factors affecting the coating efficiency and to advance the coating system development. The oxidation of catechol into quinone followed by internal cyclization via the nucleophilic attack of primary amine is crucial for DA-based surface coating. Thus, it is expected that the amine group’s nucleophilicity control directly affects the coating efficiency. However, it has not been systematically investigated, and most studies have been conducted with the focus on the transformation of amines into amides, despite such approaches decreasing the coating efficiency; the nitrogen in amides is less nucleophilic than that in free amines. In this study, we investigated the effect of N-alkylation on dopamine surface chemistry. N,N-Dimethyldopamine (DMDA) was newly synthesized, and the coating efficiency was systematically compared with DA and N-methyldopamine (MDA). DA N-monomethylation improved the coating rate by increasing the nitrogen nucleophilicity, whereas N,N-dimethylation dramatically decreased the DA surface coating property. In addition, MDA remained capable of universal surface coating and secondary reactions using the surface catechols. This study provides opportunities for developing coating materials with advanced functions and an improved coating rate.

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Section: ■ Results and Discussionmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Effect of N-Methylation on Dopamine Surface Chemistry

et al. 2022

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“…The Y-ADDA-added films showed stronger adhesion than that of bare LSS. In general, the phenol moiety in urushiol that has hydroxyl groups affects the adherence to the substrate surface. , In addition, the photo-oxidation of Y-ADDA by UV irradiation can induce the formation of catechol and quinone structures as active species with the introduction of additional hydroxyl groups as well as the formation of dityrosine, resulting in increased LSS film adhesion to a substrate. , This is why Y-ADDA can further increase the adhesion of LSS compared to other comparative additives during UV irradiation. With an increase in additive concentration, the number of phenol and catechol groups adhering to the substrate surface correspondingly increased, resulting in stronger adhesion.…”

Section: Resultsmentioning

confidence: 99%

Photo-Curable Lacquer Sap Resin Based on Urushiol-Mimicking, Tyrosine-Containing Additive

et al. 2022

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Oriental lacquer sap is attracting considerable attention as a renewable and eco-friendly natural resin with high durability, heat resistance, insulation, insect repellency, and antiseptic and antibacterial properties. However, to ensure excellent coating performance, it is necessary to improve the drying/curing process of lacquer sap with a time-consuming drying time at high humidity [relative humidity (RH), 70−90%] and ambient temperature (20−30 °C). Drawing on an understanding of the polymerization mechanism of urushiol, the main component of the lacquer sap consisted of a water-in-oil (W/O) emulsion, and this study presents an eco-friendly additive that mimics the structure−function of urushiol composed of a polar catechol head group and a nonpolar hydrocarbon tail. A photo-curable lacquer sap was thus developed by adding a tyrosine amino acid-based lipid agent (denoted as Y-ADDA), which allows faster and more effective drying/curing at lower humidity while maintaining the nature-derived properties of lacquer sap. Y-ADDA easily coassembles with urushiol in the W/O emulsion droplets, thereby significantly accelerating the formation of a polymer network along with urushiol during water evaporation leading to fast drying/curing under ultraviolet (UV) light irradiation at low humidity (∼50% RH). The UV-cured lacquer sap resins showed higher performance in terms of film processing and physicochemical properties compared with that of the lacquer containing only tyrosine amino acids without aliphatic tail conjugation, N-(9fluorenylmethoxycarbonyl)-O-tert-butyl-L-tyrosine Fmoc-Tyr(tBu)-OH. Furthermore, the drying and curing times, film morphology, transmittance, hardness, and adhesion strength of the UV-cured lacquer were markedly superior compared to those of shellac, a general eco-friendly fast-drying primer. The study provides useful strategies and insights to promote the industrial application of lacquer sap resins by employing biocompatible nanoagents developed with an understanding of the curing mechanism of natural resins and from the viewpoint of green and sustainable chemistry perspective.

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“…Thus, the self-assembly of these colloidal particles provides a facile approach to producing nanostructured materials with tailored properties. If sufficiently stable and nearly monodisperse particles are used, ordered three-dimensional arrangements, termed colloidal crystals, are formed. , Such structures exhibit in brilliant, iridescent colors, ,,, mimicking their natural analogue, the opal gemstone. − In contrast, when polydisperse or destabilized particle dispersions are used, less intense, angle-independent colors result. ,− …”

Section: Introductionmentioning

confidence: 99%

Quantitative Optical and Structural Comparison of 3D and (2+1)D Colloidal Photonic Crystals

et al. 2023

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Colloidal crystals are excellent model systems to study self-assembly and structural coloration because their periodicities coincide with the wavelength range of visible light. Different assembly methods inherently introduce characteristic defects and irregularities, even with nearly monodisperse colloidal particles. Here, we investigate how these imperfections influence the structural coloration by comparing two techniques to obtain colloidal crystals. 3D colloidal crystals produced by convective assembly are well-ordered and periodically arranged but show microscopic cracks. (2+1)D colloidal crystals fabricated by stacking individual monolayers show a decreased hexagonal order and limited crystal registration between single monolayers in the z-direction. We investigate the optical properties of both systems by comparing identical numbers of layers using correlative microspectroscopy. These measurements show that the less ordered (2+1)D colloidal crystals exhibit higher reflected light intensities. Macroscopic reflection integrating all angles shows that the reflected light intensity levels out with an increasing number of layers, whereas incoherent scattering increases. Although both types of colloidal crystal show similar angle-dependent color shifts in specular reflection, the less-ordered structure of the (2+1)D colloidal crystal scatters light within a larger angular range under diffusive illumination. Our results suggest that structural coloration is surprisingly robust toward local defects and irregularities.

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Control of Structural Coloration by Natural Sunlight Irradiation on a Melanin Precursor Polymer Inspired by Skin Tanning

Cited by 9 publications

References 63 publications

Effect of N-Methylation on Dopamine Surface Chemistry

Effect of N-Methylation on Dopamine Surface Chemistry

Photo-Curable Lacquer Sap Resin Based on Urushiol-Mimicking, Tyrosine-Containing Additive

Quantitative Optical and Structural Comparison of 3D and (2+1)D Colloidal Photonic Crystals

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