1
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Petropoulos V, Mavridi-Printezi A, Menichetti A, Mordini D, Kabacinski P, Gianneschi NC, Montalti M, Maiuri M, Cerullo G. Sub-50 fs Formation of Charge Transfer States Rules the Fate of Photoexcitations in Eumelanin-Like Materials. J Phys Chem Lett 2024; 15:3639-3645. [PMID: 38530860 DOI: 10.1021/acs.jpclett.4c00170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
Eumelanins play a crucial role as photoprotective agents for living organisms, yet the nature of the stationary and transient species involved in the light absorption and deactivation processes remains controversial. Moreover, the critical sub-100 fs time scale, which is key to the characterization of the primary excited species, has remained unexplored. Here, we study the eumelanin analogue polydopamine (PDA) and employ a combination of steady-state and transient optical spectroscopies to reveal the presence of spectrally broad coupled electronic transitions with, at least partial, charge-transfer (CT) character. We monitor the CT state dynamics using tunable sub-20 fs pulses. We find that high photon energy excitation results in accelerated (sub-20 fs) CT formation times while activating pathways, which lead to long-lived (≫1 ns), possibly reactive CT species. On the other hand, visible light excitation results in a slower (≈45 fs) formation of bound CT states, which, however, recombine on the ultrafast sub-2 ps time scale.
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Affiliation(s)
- Vasilis Petropoulos
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | | | - Arianna Menichetti
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Dario Mordini
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Piotr Kabacinski
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Nathan C Gianneschi
- Departments of Chemistry, Materials Science & Engineering, Biomedical Engineering and Pharmacology, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, California 92093, United States
| | - Marco Montalti
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Margherita Maiuri
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Giulio Cerullo
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
- Istituto di Fotonica e Nanotecnologie (IFN)-Consiglio Nazionale delle Ricerche (CNR), Piazza Leonardo da Vinci 32, 20133 Milano, Italy
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2
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Di Mauro E, Camaggi M, Vandooren N, Bayard C, De Angelis J, Pezzella A, Baloukas B, Silverwood R, Ajji A, Pellerin C, Santato C. Eumelanin for nature‐inspired UV‐absorption enhancement of plastics. POLYM INT 2019. [DOI: 10.1002/pi.5790] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Eduardo Di Mauro
- Département de Génie PhysiquePolytechnique Montréal Montréal Canada
| | - Matteo Camaggi
- Département de Génie PhysiquePolytechnique Montréal Montréal Canada
- Department of Electrical Engineering (DEI)University of Bologna Bologna Italy
| | - Nils Vandooren
- Département de Génie PhysiquePolytechnique Montréal Montréal Canada
| | - Caleb Bayard
- Département de Génie PhysiquePolytechnique Montréal Montréal Canada
| | - Jordan De Angelis
- Département de Génie PhysiquePolytechnique Montréal Montréal Canada
- Department of Electrical Engineering (DEI)University of Bologna Bologna Italy
| | - Alessandro Pezzella
- Institute for Polymers, Composites and Biomaterials (IPCB)CNR Pozzuoli Italy
| | - Bill Baloukas
- Département de Génie PhysiquePolytechnique Montréal Montréal Canada
| | - Richard Silverwood
- CREPEC, Department of Chemical EngineeringPolytechnique Montréal Montreal Canada
| | - Abdellah Ajji
- CREPEC, Department of Chemical EngineeringPolytechnique Montréal Montreal Canada
| | | | - Clara Santato
- Département de Génie PhysiquePolytechnique Montréal Montréal Canada
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3
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Panzella L, Ebato A, Napolitano A, Koike K. The Late Stages of Melanogenesis: Exploring the Chemical Facets and the Application Opportunities. Int J Mol Sci 2018; 19:E1753. [PMID: 29899264 PMCID: PMC6032422 DOI: 10.3390/ijms19061753] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 06/08/2018] [Accepted: 06/08/2018] [Indexed: 11/16/2022] Open
Abstract
In the last decade, the late stages of melanin biosynthesis involving the oxidative polymerization of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) have been extensively investigated. Most of the information derived from a biomimetic approach in which the oxidation of melanogenic indoles was carried out under conditions mimicking those occurring in the biological environment. Characterization of the early oligomers allowed for drawing a structural picture of DHI and DHICA melanins, providing also an interpretative basis for the different properties exhibited by these pigments, e.g., the chromophore and the antioxidant ability. The improved knowledge has opened new perspectives toward the exploitation of the unique chemistry of melanins and its precursors in cosmetic and health care applications. A noticeable example is the development of an innovative hair dyeing system that is based on the marked ease of DHI to give rise to black melanin on air oxidation under slightly alkaline conditions. The advantage of this method for a step-wise coverage of gray hair with a natural shade pigmentation on repeated treatment with a DHI-based formulation with respect to traditional dyes is presented. A variant of DHICA melanin combining solubility in water-miscible organic solvents, an intense chromophore in the UltraViolet-A UV-A region, and a marked antioxidant potency was evaluated as an ingredient for cosmetic formulations.
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Affiliation(s)
- Lucia Panzella
- Department of Chemical Sciences, University of Naples "Federico II", I-80126 Naples, Italy.
| | - Atsuko Ebato
- Hair Care Products Research Laboratories, Kao Corporation, Tokyo 131-8501, Japan.
| | - Alessandra Napolitano
- Department of Chemical Sciences, University of Naples "Federico II", I-80126 Naples, Italy.
| | - Kenzo Koike
- Hair Care Products Research Laboratories, Kao Corporation, Tokyo 131-8501, Japan.
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4
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Crescenzi O, D'Ischia M, Napolitano A. Kaxiras's Porphyrin: DFT Modeling of Redox-Tuned Optical and Electronic Properties in a Theoretically Designed Catechol-Based Bioinspired Platform. Biomimetics (Basel) 2017; 2:biomimetics2040021. [PMID: 31105182 PMCID: PMC6352670 DOI: 10.3390/biomimetics2040021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 10/24/2017] [Accepted: 10/26/2017] [Indexed: 11/18/2022] Open
Abstract
A detailed computational investigation of the 5,6-dihydroxyindole (DHI)-based porphyrin-type tetramer first described by Kaxiras as a theoretical structural model for eumelanin biopolymers is reported herein, with a view to predicting the technological potential of this unique bioinspired tetracatechol system. All possible tautomers/conformers, as well as alternative protonation states, were explored for the species at various degrees of oxidation and all structures were geometry optimized at the density functional theory (DFT) level. Comparison of energy levels for each oxidized species indicated a marked instability of most oxidation states except the six-electron level, and an unexpected resilience to disproportionation of the one-electron oxidation free radical species. Changes in the highest energy occupied molecular orbital (HOMO)–lowest energy unoccupied molecular orbital (LUMO) gaps with oxidation state and tautomerism were determined along with the main electronic transitions: more or less intense absorption in the visible region is predicted for most oxidized species. Data indicated that the peculiar symmetry of the oxygenation pattern pertaining to the four catechol/quinone/quinone methide moieties, in concert with the NH centers, fine-tunes the optical and electronic properties of the porphyrin system. For several oxidation levels, conjugated systems extending over two or more indole units play a major role in determining the preferred tautomeric state: thus, the highest stability of the six-electron oxidation state reflects porphyrin-type aromaticity. These results provide new clues for the design of innovative bioinspired optoelectronic materials.
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Affiliation(s)
- Orlando Crescenzi
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy.
| | - Marco D'Ischia
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy.
| | - Alessandra Napolitano
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy.
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5
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Pinna E, Melis C, Antidormi A, Cardia R, Sechi E, Cappellini G, d'Ischia M, Colombo L, Mula G. Deciphering Molecular Mechanisms of Interface Buildup and Stability in Porous Si/Eumelanin Hybrids. Int J Mol Sci 2017; 18:E1567. [PMID: 28753933 PMCID: PMC5536055 DOI: 10.3390/ijms18071567] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/05/2017] [Accepted: 07/11/2017] [Indexed: 01/28/2023] Open
Abstract
Porous Si/eumelanin hybrids are a novel class of organic-inorganic hybrid materials that hold considerable promise for photovoltaic applications. Current progress toward device setup is, however, hindered by photocurrent stability issues, which require a detailed understanding of the mechanisms underlying the buildup and consolidation of the eumelanin-silicon interface. Herein we report an integrated experimental and computational study aimed at probing interface stability via surface modification and eumelanin manipulation, and at modeling the organic-inorganic interface via formation of a 5,6-dihydroxyindole (DHI) tetramer and its adhesion to silicon. The results indicated that mild silicon oxidation increases photocurrent stability via enhancement of the DHI-surface interaction, and that higher oxidation states in DHI oligomers create more favorable conditions for the efficient adhesion of growing eumelanin.
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Affiliation(s)
- Elisa Pinna
- Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042 Monserrato, Italy.
- Istituto Officina dei Materiali CNR-IOM, Unità di Cagliari SLACS, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Monserrato, Italy.
| | - Claudio Melis
- Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042 Monserrato, Italy.
- Istituto Officina dei Materiali CNR-IOM, Unità di Cagliari SLACS, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Monserrato, Italy.
| | - Aleandro Antidormi
- Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042 Monserrato, Italy.
- Istituto Officina dei Materiali CNR-IOM, Unità di Cagliari SLACS, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Monserrato, Italy.
| | - Roberto Cardia
- Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042 Monserrato, Italy.
| | - Elisa Sechi
- Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042 Monserrato, Italy.
| | - Giancarlo Cappellini
- Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042 Monserrato, Italy.
| | - Marco d'Ischia
- Department of Organic Chemistry and Biochemistry, University of Naples "Federico II", Via Cintia 4, 80126 Naples, Italy.
| | - Luciano Colombo
- Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042 Monserrato, Italy.
- Istituto Officina dei Materiali CNR-IOM, Unità di Cagliari SLACS, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Monserrato, Italy.
| | - Guido Mula
- Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042 Monserrato, Italy.
- Istituto Officina dei Materiali CNR-IOM, Unità di Cagliari SLACS, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Monserrato, Italy.
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6
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Ghosh P, Ghosh D. Elucidating the Photoprotection Mechanism of Eumelanin Monomers. J Phys Chem B 2017; 121:5988-5994. [DOI: 10.1021/acs.jpcb.7b05123] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Paulami Ghosh
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Debashree Ghosh
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Pune 411008, India
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7
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Micillo R, Panzella L, Iacomino M, Prampolini G, Cacelli I, Ferretti A, Crescenzi O, Koike K, Napolitano A, d'Ischia M. Eumelanin broadband absorption develops from aggregation-modulated chromophore interactions under structural and redox control. Sci Rep 2017; 7:41532. [PMID: 28150707 PMCID: PMC5288692 DOI: 10.1038/srep41532] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 12/19/2016] [Indexed: 12/18/2022] Open
Abstract
Eumelanins, the chief photoprotective pigments in man and mammals, owe their black color to an unusual broadband absorption spectrum whose origin is still a conundrum. Excitonic effects from the interplay of geometric order and disorder in 5,6-dihydroxyindole (DHI)-based oligomeric/polymeric structures play a central role, however the contributions of structural (scaffold-controlled) and redox (π-electron-controlled) disorder have remained uncharted. Herein, we report an integrated experimental-theoretical entry to eumelanin chromophore dynamics based on poly(vinyl alcohol)-controlled polymerization of a large set of 5,6-dihydroxyindoles and related dimers. The results a) uncover the impact of the structural scaffold on eumelanin optical properties, disproving the widespread assumption of a universal monotonic chromophore; b) delineate eumelanin chromophore buildup as a three-step dynamic process involving the rapid generation of oxidized oligomers, termed melanochromes (phase I), followed by a slow oxidant-independent band broadening (phase II) leading eventually to scattering (phase III); c) point to a slow reorganization-stabilization of melanochromes via intermolecular redox interactions as the main determinant of visible broadband absorption.
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Affiliation(s)
- Raffaella Micillo
- Department of Clinical Medicine and Surgery, University of Naples Federico II, I-80131 Naples, Italy
| | - Lucia Panzella
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy
| | - Mariagrazia Iacomino
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy
| | - Giacomo Prampolini
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca, I-56124 Pisa, Italy
| | - Ivo Cacelli
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca, I-56124 Pisa, Italy.,Dipartimento di Chimica e Chimica Industriale, Università di Pisa, I-56124 Pisa, Italy
| | - Alessandro Ferretti
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca, I-56124 Pisa, Italy
| | - Orlando Crescenzi
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy
| | - Kenzo Koike
- Hair care Products Research Laboratories, Kao Corporation, Tokyo 131-8501, Japan
| | - Alessandra Napolitano
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy
| | - Marco d'Ischia
- Department of Chemical Sciences, University of Naples Federico II, I-80126 Naples, Italy
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8
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Tuna D, Udvarhelyi A, Sobolewski AL, Domcke W, Domratcheva T. Onset of the Electronic Absorption Spectra of Isolated and π-Stacked Oligomers of 5,6-Dihydroxyindole: An Ab Initio Study of the Building Blocks of Eumelanin. J Phys Chem B 2016; 120:3493-502. [PMID: 27005558 DOI: 10.1021/acs.jpcb.6b01793] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Eumelanin is a naturally occurring skin pigment which is responsible for developing a suntan. The complex structure of eumelanin consists of π-stacked oligomers of various indole derivatives, such as the monomeric building block 5,6-dihydroxyindole (DHI). In this work, we present an ab initio wave-function study of the absorption behavior of DHI oligomers and of doubly and triply π-stacked species of these oligomers. We have simulated the onset of the electronic absorption spectra by employing the MP2 and the linear-response CC2 methods. Our results demonstrate the effect of an increasing degree of oligomerization of DHI and of an increasing degree of π-stacking of DHI oligomers on the onset of the absorption spectra and on the degree of red-shift toward the visible region of the spectrum. We find that π-stacking of DHI and its oligomers substantially red-shifts the onset of the absorption spectra. Our results also suggest that the optical properties of biological eumelanin cannot be simulated by considering the DHI building blocks alone, but instead the building blocks indole-semiquinone and indole-quinone have to be considered as well. This study contributes to advancing the understanding of the complex photophysics of the eumelanin biopolymer.
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Affiliation(s)
- Deniz Tuna
- Department of Chemistry, Technische Universität München , 85747 Garching, Germany
| | - Anikó Udvarhelyi
- Department of Biomolecular Mechanisms, Max-Planck-Institut für Medizinische Forschung , 69120 Heidelberg, Germany
| | | | - Wolfgang Domcke
- Department of Chemistry, Technische Universität München , 85747 Garching, Germany
| | - Tatiana Domratcheva
- Department of Biomolecular Mechanisms, Max-Planck-Institut für Medizinische Forschung , 69120 Heidelberg, Germany
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9
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Fan KW, Peterson MB, Ellersdorfer P, Granville AM. Expanding the aqueous-based redox-facilitated self-polymerization chemistry of catecholamines to 5,6-dihydroxy-1H-benzimidazole and its 2-substituted derivatives. RSC Adv 2016. [DOI: 10.1039/c5ra25590b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Redox-facilitated self-polymerization can be performed with 5,6-dihydroxy-1H-benzimidazole to generate materials analogous to polydopamine, proving the possibility to expand the catecholamine-based chemistry to N-heterocyclic catechol derivatives.
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Affiliation(s)
- Ka Wai Fan
- Centre for Advanced Macromolecular Design
- School of Chemical Engineering
- The University of New South Wales
- Kensington
- Australia
| | | | - Peter Ellersdorfer
- Centre for Advanced Macromolecular Design
- School of Chemical Engineering
- The University of New South Wales
- Kensington
- Australia
| | - Anthony M. Granville
- Centre for Advanced Macromolecular Design
- School of Chemical Engineering
- The University of New South Wales
- Kensington
- Australia
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10
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Vitiello G, Pezzella A, Zanfardino A, Varcamonti M, Silvestri B, Costantini A, Branda F, Luciani G. Titania as a driving agent for DHICA polymerization: a novel strategy for the design of bioinspired antimicrobial nanomaterials. J Mater Chem B 2015; 3:2808-2815. [DOI: 10.1039/c5tb00039d] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Organic materials are widely employed to tune surface chemistry and/or as structuring agents of inorganic materials.
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Affiliation(s)
- Giuseppe Vitiello
- Dipartimento di Ingegneria Chimica
- dei Materiali e della Produzione Industriale
- Università di Napoli “Federico II”
- 80125 Napoli
- Italy
| | - Alessandro Pezzella
- Dipartimento di Scienze Chimiche
- Università di Napoli “Federico II” via Cintia 4
- 80126 Napoli
- Italy
| | - Anna Zanfardino
- Dipartimento di Biologia
- Università di Napoli “Federico II” via Cintia 4
- 80126 Napoli
- Italy
| | - Mario Varcamonti
- Dipartimento di Biologia
- Università di Napoli “Federico II” via Cintia 4
- 80126 Napoli
- Italy
| | - Brigida Silvestri
- Dipartimento di Ingegneria Chimica
- dei Materiali e della Produzione Industriale
- Università di Napoli “Federico II”
- 80125 Napoli
- Italy
| | - Aniello Costantini
- Dipartimento di Ingegneria Chimica
- dei Materiali e della Produzione Industriale
- Università di Napoli “Federico II”
- 80125 Napoli
- Italy
| | - Francesco Branda
- Dipartimento di Ingegneria Chimica
- dei Materiali e della Produzione Industriale
- Università di Napoli “Federico II”
- 80125 Napoli
- Italy
| | - Giuseppina Luciani
- Dipartimento di Ingegneria Chimica
- dei Materiali e della Produzione Industriale
- Università di Napoli “Federico II”
- 80125 Napoli
- Italy
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11
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d’Ischia M, Napolitano A, Ball V, Chen CT, Buehler MJ. Polydopamine and eumelanin: from structure-property relationships to a unified tailoring strategy. Acc Chem Res 2014; 47:3541-50. [PMID: 25340503 DOI: 10.1021/ar500273y] [Citation(s) in RCA: 370] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
CONSPECTUS: Polydopamine (PDA), a black insoluble biopolymer produced by autoxidation of the catecholamine neurotransmitter dopamine (DA), and synthetic eumelanin polymers modeled to the black functional pigments of human skin, hair, and eyes have burst into the scene of materials science as versatile bioinspired functional systems for a very broad range of applications. PDA is characterized by extraordinary adhesion properties providing efficient and universal surface coating for diverse settings that include drug delivery, microfluidic systems, and water-treatment devices. Synthetic eumelanins from dopa or 5,6-dihydroxyindoles are the focus of increasing interest as UV-absorbing agents, antioxidants, free radical scavengers, and water-dependent hybrid electronic-ionic semiconductors. Because of their peculiar physicochemical properties, eumelanins and PDA hold considerable promise in nanomedicine and bioelectronics, as they are biocompatible, biodegradable, and exhibit suitable mechanical properties for integration with biological tissues. Despite considerable similarities, very few attempts have so far been made to provide an integrated unifying perspective of these two fields of technology-oriented chemical research, and progress toward application has been based more on empirical approaches than on a solid conceptual framework of structure-property relationships. The present Account is an attempt to fill this gap. Following a vis-à-vis of PDA and eumelanin chemistries, it provides an overall view of the various levels of chemical disorder in both systems and draws simple correlations with physicochemical properties based on experimental and computational approaches. The potential of large-scale simulations to capture the macroproperties of eumelanin-like materials and their hierarchical structures, to predict the physicochemical properties of new melanin-inspired materials, to understand the structure-property-function relationships of these materials from the bottom up, and to design and optimize materials to achieve desired properties is illustrated. The impact of synthetic conditions on melanin structure and physicochemical properties is systematically discussed for the first time. Rational tailoring strategies directed to critical control points of the synthetic pathways, such as dopaquinone, DAquinone, and dopachrome, are then proposed, with a view to translating basic chemical knowledge into practical guidelines for material manipulation and tailoring. This key concept is exemplified by the recent demonstration that varying DA concentration, or using Tris instead of phosphate as the buffer, results in PDA materials with quite different structural properties. Realizing that PDA and synthetic eumelanins belong to the same family of functional materials may foster unprecedented synergisms between research fields that have so far been apart in the pursuit of tailorable and marketable materials for energy, biomedical, and environmental applications.
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Affiliation(s)
- Marco d’Ischia
- Department
of Chemical Sciences, University of Naples Federico II, Via Cintia
4, I-80126 Naples, Italy
| | - Alessandra Napolitano
- Department
of Chemical Sciences, University of Naples Federico II, Via Cintia
4, I-80126 Naples, Italy
| | - Vincent Ball
- Faculty of
Dental Surgery, University of Strasbourg, 8 rue Sainte Elizabeth Strasbourg, FR 67070 Strasbourg, France
- Institut National
de la Santé et de la Recherche Médicale, Unité
Mixte de Recherche 1121 11 rue Humann, 67085 Strasbourg Cedex, France
| | - Chun-Teh Chen
- Department
of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Markus J. Buehler
- Department
of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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12
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Fornander LH, Feng B, Beke-Somfai T, Nordén B. UV Transition Moments of Tyrosine. J Phys Chem B 2014; 118:9247-57. [DOI: 10.1021/jp5065352] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Louise H. Fornander
- Department of Chemical and
Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Bobo Feng
- Department of Chemical and
Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Tamás Beke-Somfai
- Department of Chemical and
Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Bengt Nordén
- Department of Chemical and
Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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13
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Piacenti-Silva M, Bronze-Uhle E, Paulin J, Graeff C. Temperature-enhanced synthesis of DMSO-Melanin. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2013.10.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Ascione L, Pezzella A, Ambrogi V, Carfagna C, d'Ischia M. Intermolecular π-Electron Perturbations Generate Extrinsic Visible Contributions to Eumelanin Black Chromophore in Model Polymers with Interrupted Interring Conjugation. Photochem Photobiol 2012; 89:314-8. [DOI: 10.1111/php.12003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 09/20/2012] [Indexed: 12/01/2022]
Affiliation(s)
- Laura Ascione
- Department of Chemical Sciences; University of Naples Federico II; Naples; Italy
| | - Alessandro Pezzella
- Department of Chemical Sciences; University of Naples Federico II; Naples; Italy
| | - Veronica Ambrogi
- Department of Materials and Production Engineering; University of Naples Federico II; Naples; Italy
| | | | - Marco d'Ischia
- Department of Chemical Sciences; University of Naples Federico II; Naples; Italy
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15
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Synthesis and structural characterization of soluble neuromelanin analogs provides important clues to its biosynthesis. J Biol Inorg Chem 2012; 18:81-93. [DOI: 10.1007/s00775-012-0951-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 10/11/2012] [Indexed: 10/27/2022]
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16
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Corani A, Huijser A, Iadonisi A, Pezzella A, Sundström V, d’Ischia M. Bottom-Up Approach to Eumelanin Photoprotection: Emission Dynamics in Parallel Sets of Water-Soluble 5,6-Dihydroxyindole-Based Model Systems. J Phys Chem B 2012; 116:13151-8. [DOI: 10.1021/jp306436f] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alice Corani
- Department of Chemical Physics, Lund University, Box 124, 221 00 Lund, Sweden
| | - Annemarie Huijser
- Department of Chemical Physics, Lund University, Box 124, 221 00 Lund, Sweden
| | - Alfonso Iadonisi
- Department of Chemical Sciences, University of Naples “Federico II”, Via
Cintia, 80126 Naples, Italy
| | - Alessandro Pezzella
- Department of Chemical Sciences, University of Naples “Federico II”, Via
Cintia, 80126 Naples, Italy
| | - Villy Sundström
- Department of Chemical Physics, Lund University, Box 124, 221 00 Lund, Sweden
| | - Marco d’Ischia
- Department of Chemical Sciences, University of Naples “Federico II”, Via
Cintia, 80126 Naples, Italy
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17
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Mula G, Manca L, Setzu S, Pezzella A. Photovoltaic properties of PSi impregnated with eumelanin. NANOSCALE RESEARCH LETTERS 2012; 7:377. [PMID: 22776626 PMCID: PMC3420258 DOI: 10.1186/1556-276x-7-377] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 07/09/2012] [Indexed: 06/01/2023]
Abstract
A bulk heterojunction of porous silicon and eumelanin, where the columnar pores of porous silicon are filled with eumelanin, is proposed as a new organic-inorganic hybrid material for photovoltaic applications. The addition of eumelanin, whose absorption in the near infrared region is significantly higher than porous silicon, should greatly enhance the light absorption capabilities of the empty porous silicon matrix, which are very low in the low energy side of the visible spectral range (from about 600 nm downwards). The experimental results show that indeed the photocarrier collection efficiency at longer wavelengths in eumelanin-impregnated samples is clearly higher with respect to empty porous silicon matrices.
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Affiliation(s)
- Guido Mula
- Dipartimento di Fisica, Cittadella Universitaria di Monserrato, Università degli Studi di Cagliari, S.P. 8 km 0.7, Monserrato (Ca), 09042, Italy
| | - Laura Manca
- Dipartimento di Fisica, Cittadella Universitaria di Monserrato, Università degli Studi di Cagliari, S.P. 8 km 0.7, Monserrato (Ca), 09042, Italy
| | - Susanna Setzu
- Dipartimento di Fisica, Cittadella Universitaria di Monserrato, Università degli Studi di Cagliari, S.P. 8 km 0.7, Monserrato (Ca), 09042, Italy
| | - Alessandro Pezzella
- Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, Via Cintia, Napoli, 4-80126, Italy
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18
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Peles DN, Simon JD. UV-absorption spectra of melanosomes containing varying 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid content. J Phys Chem B 2011; 115:12624-31. [PMID: 21923179 DOI: 10.1021/jp2060624] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Central to understanding the photochemical properties of melanosomes is a direct measurement of their absorption coefficients. Herein, the absorption spectra of intact melanosomes of varying molecular compositions and embryonic origins were measured and compared over the spectral range from 245 to 310 nm. The absorption spectra of melanosomes predominately comprised of the eumelanin pigment were found to differ significantly from their constituent precursor molecules, 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). This difference was most notable in the UV-A region and indicates that the electronic structures of the monomeric building blocks, DHICA in particular, are significantly modified upon polymerization to the melanin pigment. Furthermore, in comparing embryonic differences, the absorption coefficients of melanosomes isolated from bovine retinal pigment epithelial (RPE) cells (originating from the primitive forebrain) were greater than those for bovine choroid or iris melanosomes (originating from the neural crest). This difference suggests that either the pigment is present in greater density in RPE melanosomes or that there is an underlying difference in molecular structure.
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Affiliation(s)
- Dana N Peles
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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19
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d'Ischia M, Napolitano A, Pezzella A. 5,6‐Dihydroxyindole Chemistry: Unexplored Opportunities Beyond Eumelanin. European J Org Chem 2011. [DOI: 10.1002/ejoc.201100796] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marco d'Ischia
- Department of Organic Chemistry and Biochemistry, University of Naples “Federico II”, Via Cintia 4, 80126 Naples, Italy
| | - Alessandra Napolitano
- Department of Organic Chemistry and Biochemistry, University of Naples “Federico II”, Via Cintia 4, 80126 Naples, Italy
| | - Alessandro Pezzella
- Department of Organic Chemistry and Biochemistry, University of Naples “Federico II”, Via Cintia 4, 80126 Naples, Italy
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20
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Capelli L, Crescenzi O, Manini P, Pezzella A, Barone V, d’Ischia M. π-Electron Manipulation of the 5,6-Dihydroxyindole/Quinone System by 3-Alkynylation: Mild Acid-Mediated Entry to (Cross)-Conjugated Scaffolds and Paradigms for Medium-Tunable Chromophores. J Org Chem 2011; 76:4457-66. [DOI: 10.1021/jo200232t] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | - Vincenzo Barone
- Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
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21
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Coletta A, Morozzo della Rocca B, Jaisankar P, Majumder HK, Chillemi G, Sanna N, Desideri A. Assignment of UV−vis Spectrum of (3,3′)-Diindolylmethane, a Leishmania donovani Topoisomerase IB Inhibitor and a Candidate DNA Minor Groove Binder. J Phys Chem A 2010; 114:7121-6. [PMID: 20550156 DOI: 10.1021/jp101494d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrea Coletta
- Dipartimento di Biologia, Universitá degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica, 00133 Roma, Italy, Departments of Medicinal Chemistry and Parasitology, Indian Institut of Chemical Biology, 4 Raja S.C. Mullick Road, Kolkata-700032, India, and CASPUR Interuniversities Consortium for Supercomputing Applications, Via dei Tizii 6b, 00185 Roma, Italy
| | - Blasco Morozzo della Rocca
- Dipartimento di Biologia, Universitá degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica, 00133 Roma, Italy, Departments of Medicinal Chemistry and Parasitology, Indian Institut of Chemical Biology, 4 Raja S.C. Mullick Road, Kolkata-700032, India, and CASPUR Interuniversities Consortium for Supercomputing Applications, Via dei Tizii 6b, 00185 Roma, Italy
| | - Parasuraman Jaisankar
- Dipartimento di Biologia, Universitá degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica, 00133 Roma, Italy, Departments of Medicinal Chemistry and Parasitology, Indian Institut of Chemical Biology, 4 Raja S.C. Mullick Road, Kolkata-700032, India, and CASPUR Interuniversities Consortium for Supercomputing Applications, Via dei Tizii 6b, 00185 Roma, Italy
| | - Hemanta K. Majumder
- Dipartimento di Biologia, Universitá degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica, 00133 Roma, Italy, Departments of Medicinal Chemistry and Parasitology, Indian Institut of Chemical Biology, 4 Raja S.C. Mullick Road, Kolkata-700032, India, and CASPUR Interuniversities Consortium for Supercomputing Applications, Via dei Tizii 6b, 00185 Roma, Italy
| | - Giovanni Chillemi
- Dipartimento di Biologia, Universitá degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica, 00133 Roma, Italy, Departments of Medicinal Chemistry and Parasitology, Indian Institut of Chemical Biology, 4 Raja S.C. Mullick Road, Kolkata-700032, India, and CASPUR Interuniversities Consortium for Supercomputing Applications, Via dei Tizii 6b, 00185 Roma, Italy
| | - Nico Sanna
- Dipartimento di Biologia, Universitá degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica, 00133 Roma, Italy, Departments of Medicinal Chemistry and Parasitology, Indian Institut of Chemical Biology, 4 Raja S.C. Mullick Road, Kolkata-700032, India, and CASPUR Interuniversities Consortium for Supercomputing Applications, Via dei Tizii 6b, 00185 Roma, Italy
| | - Alessandro Desideri
- Dipartimento di Biologia, Universitá degli Studi di Roma “Tor Vergata”, Via della Ricerca Scientifica, 00133 Roma, Italy, Departments of Medicinal Chemistry and Parasitology, Indian Institut of Chemical Biology, 4 Raja S.C. Mullick Road, Kolkata-700032, India, and CASPUR Interuniversities Consortium for Supercomputing Applications, Via dei Tizii 6b, 00185 Roma, Italy
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22
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Pezzella A, Ambrogi V, Arzillo M, Napolitano A, Carfagna C, d'Ischia M. 5,6-Dihydroxyindole oxidation in phosphate buffer/polyvinyl alcohol: a new model system for studies of visible chromophore development in synthetic eumelanin polymers. Photochem Photobiol 2010; 86:533-7. [PMID: 20408984 DOI: 10.1111/j.1751-1097.2010.00730.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The determinants of the broadband absorption spectrum of eumelanins are still largely unknown. Herein we report a novel approach to investigate eumelanin chromophore which is based on the biomimetic oxidation of the key monomer precursor, 5,6-dihydroxyindole (DHI, 1), with peroxidase/hydrogen peroxide in phosphate buffer, pH 7, containing 1-5% polyvinylalcohol (PVA, 27 000 Da). This approach relies on the discovery that as low as 1% PVA can prevent precipitation of the growing melanin polymer thus allowing investigation of the chromophoric phases accompanying oxidation of DHI without confounding scattering effects. Spectrophotometric monitoring showed the initial development of a band around 530 nm persisting for about 1 h before gradually changing into the typical broadband spectrum of eumelanin. Reductive treatment caused a significant absorbance decrease in the visible region without affecting an absorption band around 320 nm. Initial product analysis indicated an altered formation ratio of 2,4'-biindolyl (2) and 2,7'-biindolyl (3) relative to control experiments. Overall, these results demonstrate for the first time that the development in solution of visible chromophores since the early oligomer stages is independent of strong aggregation/precipitation phenomena.
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Affiliation(s)
- Alessandro Pezzella
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Naples, Italy.
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23
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Okuda H, Wakamatsu K, Ito S, Sota T. Regioselectivity on the cooxidation of 5,6-dihydroxyindole and its 2-carboxy derivative from the quantum chemical calculations. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.03.054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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24
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Peles DN, Simon JD. Direct Measurement of the Ultraviolet Absorption Coefficient of Single Retinal Melanosomes. Photochem Photobiol 2010; 86:279-81. [DOI: 10.1111/j.1751-1097.2009.00656.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Pezzella A, Iadonisi A, Valerio S, Panzella L, Napolitano A, Adinolfi M, d'Ischia M. Disentangling eumelanin "black chromophore": visible absorption changes as signatures of oxidation state- and aggregation-dependent dynamic interactions in a model water-soluble 5,6-dihydroxyindole polymer. J Am Chem Soc 2010; 131:15270-5. [PMID: 19919162 DOI: 10.1021/ja905162s] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A fundamental unsettled issue concerning eumelanins, the functional biopolymers of human skin and hair, is why they are black. The experimental difficulty lies in the virtual insolubility of these pigments, causing marked scattering effects and hindering characterization of the intrinsic absorption properties of the heterogeneous species produced by oxidative polymerization of 5,6-dihydroxyindole (DHI) and related monomer precursors. The synthesis of spectrally robust, water-soluble DHI polymers is therefore an important goal in the prospects of disentangling intrinsic absorption properties of eumelanin components by circumventing scattering effects. Reported herein is the first water-soluble DHI polymer produced by oxidation of ad hoc designed 5,6-dihydroxy-3-indolyl-1-thio-beta-D-galactopyranoside (1). The dark brown polymer exhibited a distinct band at 314 nm and a broad visible absorption, resembling that of natural eumelanins. Main isolable oligomer intermediates including 2,7'- and 2,4'-biindolyls 2 and 3, attest the close resemblance to the mode of coupling of the parent DHI. Sodium borohydride reduction caused decoloration and a marked absorbance decrease in the visible region around 550 nm, but did not affect the UV band at 314 nm. Measurements of absorbance variations with dilution indicated a linear response at 314 nm, but a significant deviation from linearity in the visible region, with the largest decrease around 500 nm. It is argued that eumelanin black color is not only intrinsically defined by the overlap of pi-electron conjugated chromophores within the individual polymer components, as commonly believed, but also by oxidation state- and aggregation-dependent interchromophoric interactions causing perturbations of the heterogeneous ensemble of pi-electron systems and overall spectral broadening.
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Affiliation(s)
- Alessandro Pezzella
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II Complesso Universitario Monte S. Angelo, Via Cintia 4, I-80126 Naples, Italy.
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26
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Capelli L, Manini P, Pezzella A, d'Ischia M. First synthetic entry to the trimer stage of 5,6-dihydroxyindole polymerization: ortho-alkynylaniline-based access to the missing 2,7′:2′,7′′-triindole. Org Biomol Chem 2010; 8:4243-5. [DOI: 10.1039/c0ob00037j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Capelli L, Manini P, Pezzella A, Napolitano A, d’Ischia M. Efficient Synthesis of 5,6-Dihydroxyindole Dimers, Key Eumelanin Building Blocks, by a Unified o-Ethynylaniline-Based Strategy for the Construction of 2-Linked Biindolyl Scaffolds. J Org Chem 2009; 74:7191-4. [DOI: 10.1021/jo901259s] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Luigia Capelli
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, via Cintia 4, I-80126 Naples, Italy
| | - Paola Manini
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, via Cintia 4, I-80126 Naples, Italy
| | - Alessandro Pezzella
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, via Cintia 4, I-80126 Naples, Italy
| | - Alessandra Napolitano
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, via Cintia 4, I-80126 Naples, Italy
| | - Marco d’Ischia
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, via Cintia 4, I-80126 Naples, Italy
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28
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d'Ischia M, Napolitano A, Pezzella A, Meredith P, Sarna T. Chemische und strukturelle Vielfalt der Eumelanine - ein kaum erforschtes optoelektronisches Biopolymer. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200803786] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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29
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d'Ischia M, Napolitano A, Pezzella A, Meredith P, Sarna T. Chemical and structural diversity in eumelanins: unexplored bio-optoelectronic materials. Angew Chem Int Ed Engl 2009; 48:3914-21. [PMID: 19294706 PMCID: PMC2799031 DOI: 10.1002/anie.200803786] [Citation(s) in RCA: 373] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Eumelanins, the characteristic black, insoluble, and heterogeneous biopolymers of human skin, hair, and eyes, have intrigued and challenged generations of chemists, physicists, and biologists because of their unique structural and optoelectronic properties. Recently, the methods of organic chemistry have been combined with advanced spectroscopic and imaging techniques, theoretical calculations, and methods of condensed-matter physics to gradually force these materials to reveal their secrets. Herein we review the latest advances in the field with a view to showing how the emerging knowledge is not only helping to explain eumelanin functionality, but may also be translated into effective strategies for exploiting their properties to create a new class of biologically inspired high-tech materials.
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Affiliation(s)
- Marco d'Ischia
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, I-80126, Naples, Italy.
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30
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Duong HA, Chua S, Huleatt PB, Chai CLL. Synthesis of Biindolyls via Palladium-Catalyzed Reactions. J Org Chem 2008; 73:9177-80. [DOI: 10.1021/jo801846b] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hung A. Duong
- Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), 1 Pesek Rd, Jurong Island, Singapore 627833
| | - Sheena Chua
- Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), 1 Pesek Rd, Jurong Island, Singapore 627833
| | - Paul B. Huleatt
- Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), 1 Pesek Rd, Jurong Island, Singapore 627833
| | - Christina L. L. Chai
- Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), 1 Pesek Rd, Jurong Island, Singapore 627833
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31
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Simon JD, Hong L, Peles DN. Insights into melanosomes and melanin from some interesting spatial and temporal properties. J Phys Chem B 2008; 112:13201-17. [PMID: 18817437 DOI: 10.1021/jp804248h] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Melanosomes are organelles found in a wide variety of tissues throughout the animal kingdom and exhibit a range of different shapes: spheres of up to approximately 1 mum diameters and ellipsoids with lengths of up to approximately 2 mum and varying aspect ratios. The functions of melanosomes include photoprotection, mitigation of the effects of reactive oxygen species, and metal chelation. The melanosome contains a variety of biological molecules, e.g., proteins and lipids, but the dominant constituent is the pigment melanin, and the functions ascribed to melanosomes are uniquely enabled by the chemical properties of the melanins they contain. In the past decade, there has been significant progress in understanding melanins and their impact on human health. While the molecular details of melanin production and how the pigment is organized within the melanosome determine its properties and biological functions, the physical and chemical properties of the surface of the melanosome are central to their range of ascribed functions. Surprisingly, few studies designed to probe this biological surface have been reported. In this article, we discuss recent work using surface-sensitive analytic, spectroscopic, and imaging techniques to examine the structural and chemical properties of many types of natural pigments: sepia melanin granules, human and bovine ocular melanosomes, human hair melanosomes, and neuromelanin. N 2 adsorption/desorption measurements and atomic force microscopy provide novel insights into surface morphology. The chemical properties of the melanins present on the surface are revealed by X-ray photoelectron spectroscopy and photoemission electron microscopy. These technologies are also applied to elucidate changes in surface properties that occur with aging. Specifically, studies of the surface properties of human retinal pigment epithelium melanosomes as a function of age are stimulating the development of models for their age-dependent behaviors. The article concludes with a brief discussion of important unanswered research questions in this field.
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Affiliation(s)
- John D Simon
- Department of Chemistry, Duke UNiversity, Durham, NC, USA
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