Chemische und strukturelle Vielfalt der Eumelanine – ein kaum erforschtes optoelektronisches Biopolymer

d’Ischia, Marco; Napolitano, Alessandra; Pezzella, Alessandro; Meredith, Paul; Sarna, Tadeusz

doi:10.1002/ange.200803786

Cited by 47 publications

(23 citation statements)

References 91 publications

(109 reference statements)

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“…[4b, 18,28] In contrast, the oxidation of pyrocatechol passes through aq uinone intermediate and leads to polyphenolic crosslinking (Scheme 1, right). Thed ifference in the pelectron density of the side aromatic groups in pNE (polyindolic crosslinking) and pPC (polyphenolic crosslinking) could result in different strengths of p-p stacking (the quadrupole-quadrupole interaction).…”

Section: Methodsmentioning

confidence: 95%

“…[4b, 18,28] Because pKa 1 and pKa 2 of NE are 8.64 and 9.70, respectively, [29] the primary amine group in NE will exist in the protonated form at pH 8.4, at which the experiment was conducted. In addition, the deprotonation pKao fi ndole is approximately 17, and as most of the resonance structures of indole bear apositive charge on the nitrogen atom, [30] we may infer that quaternary amine exists in pNE.…”

Section: Methodsmentioning

confidence: 99%

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Nanomechanics of Poly(catecholamine) Coatings in Aqueous Solutions

et al. 2016

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Mussel-inspired self-polymerized catecholamine coatings have been widely utilized as a versatile coating strategy that can be applied to a variety of substrates. For the first time, nanomechanical measurements and an evaluation of the contribution of primary amine groups to poly(catecholamine) coatings have been conducted using a surface-forces apparatus. The adhesive strength between the poly(catecholamine) layers is 30-times higher than that of a poly(catechol) coating. The origin of the strong attraction between the poly(catecholamine) layers is probably due to surface salt displacement by the primary amine, π-π stacking (the quadrupole-quadrupole interaction of indolic crosslinks), and cation-π interactions (the monopole-quadrupole interaction between positively charged amine groups and the indolic crosslinks). The contribution of the primary amine group to the catecholamine coating is vital for the design and development of mussel-inspired catechol-based coating materials.

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Section: Methodsmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Nanomechanics of Poly(catecholamine) Coatings in Aqueous Solutions

et al. 2016

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“…[12] This material can bind proteins in a covalent manner at physiological pH [13,14] and absorbs light over the whole UV/Vis spectrum owing to its structure, most probably consisting of polydisperse 5,6-dihydroxyindole aggregates. [15,16] Melanin particles from Sepia officinalis have a hierarchical structure, as revealed by atomic force microscopy. [17] Melanin is fascinating from a fundamental point of view owing to its incompletely explained structure and black colour.…”

Section: Introductionmentioning

confidence: 98%

Melanin‐Containing Films: Growth from Dopamine Solutions versus Layer‐by‐Layer Deposition

et al. 2010

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Films formed by oxidation of dopamine are of interest for functionalisation of solid-liquid interfaces owing to their versatility. However, the ability to modulate the properties of such films, for example, permeability to ionic species and the absorption coefficient, is urgently needed. Indeed, melanin films produced by oxidation of dopamine absorb strongly over the whole UV/Vis part of the electromagnetic spectrum and are impermeable to anions even for a film thickness as low as a few nanometers. Herein we combine oxidation of dopamine to produce a solution containing dopamine-melanin particles and their alternating deposition with poly(diallyldimethylammonium chloride) to produce films which have nearly the same morphology as pure dopamine-melanin films but are less compact, more transparent and more permeable to ferrocyanide anions.

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“…Concerning the catechol moiety, eumelanin is mainly composed of oligomers of 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid [99], and neuromelanin is hypothesized to be a copolymer including the dihydroxyindole unit [100]. Even though extensive research has been carried out on their structure, melanins are among the last few biomacromolecular systems for which the organization of their constituent molecules, and its relation to precise biological functions, is still controversial, in part because of melanin's notorious lack of solubility in all solvents, which makes its chemistry particularly challenging [101,102]. The question of whether melanins are formed by high-molecular weight polymeric chains or aggregates of oligomers (protomolecules) is still not settled, although recent spectroscopic evidence seems to favor the latter theory [101,103].…”

Section: Melaninmentioning

confidence: 99%

Catechol‐Based Biomimetic Functional Materials and their Applications

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Sedó

Ruiz‐Molina

et al. 2014

Bio‐ and Bioinspired Nanomaterials

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A prime example of how biomaterials can inspire their fabricated counterparts is the case of catechol-based materials. Catechols are aromatic derivatives with two adjacent (ortho-) hydroxyl groups; they are ubiquitous in nature, taking part in a remarkable range of processes and functions. This functional versatility can be explained considering that catechols can act as weak acids and, simultaneously, as easily oxidizable reducing agents. In addition, the presence of two hydroxyl groups in vicinal positions in the aromatic ring makes them ideal for bidentate coordination and intermolecular interactions.Intense research has been aimed at mimicking the natural roles of catechols by developing new functional materials. This chapter will focus on past and recent studies involving the design, development, and biomimetic use of synthetic molecules and materials with catechols present in their structure, mainly in the fields of biomedicine, analytical, nanotechnology, and materials science, and showing the potential of this chemical functionality to afford promising candidate structures for technologically relevant applications.This chapter is structured considering the main functional roles of the catechol moiety in the molecules and materials fabricated, either as individual molecules or as part of a polymeric backbone. Thus, the three first sections are devoted to cases where catechols act as linkers between: macroscopic surfaces, acting as adhesives (Section 11.2); macroscopic surfaces and functional molecules (Section 11.3); and outer parts of micro-or nanoscopic structures and functional molecules (Section 11.4). Section 11.5 is focused in the role of catechols as constituent blocks of functional 2D or 3D scaffolds and structures. Next, the chelating properties of catechols and their function for metal sequestration are addressed in Section 11.6. Finally, the two last sections are centered on their presence in different sensors (Section 11.7) and electronic devices (Section 11.8), owing to the redox features of the catechol/quinone system.

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Chemische und strukturelle Vielfalt der Eumelanine – ein kaum erforschtes optoelektronisches Biopolymer

Cited by 47 publications

References 91 publications

Nanomechanics of Poly(catecholamine) Coatings in Aqueous Solutions

Nanomechanics of Poly(catecholamine) Coatings in Aqueous Solutions

Melanin‐Containing Films: Growth from Dopamine Solutions versus Layer‐by‐Layer Deposition

Catechol‐Based Biomimetic Functional Materials and their Applications

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