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Motovilov KA, Mostert AB. Melanin: Nature's 4th bioorganic polymer. SOFT MATTER 2024; 20:5635-5651. [PMID: 39012013 DOI: 10.1039/d4sm00491d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/17/2024]
Abstract
The pigments known as the melanins are widely recognized for their responsibility in the coloration of human skin, eyes, hair, and minimising the harmful effects of solar ultraviolet radiation. But specialists are aware that the melanins are present in all living kingdoms, barring viruses, and have functionality that extends beyond neutralizing ionising radiation. The ubiquitous presence of melanin in almost all human organs, recognized in recent years, as well as the presence of melanin in organisms that are evolutionarily distant from each other, indicate the fundamental importance of this class of material for all life forms. In this review, we argue for the need to accept melanins as the fourth primordial class of biological polymers, along with nucleic acids, proteins and polysaccharides. We consistently compare the properties of these canonical biological polymers with the properties of melanin and highlight key features that fundamentally distinguish melanins, their function and its mysteries.
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Affiliation(s)
- K A Motovilov
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny 141701, Moscow Region, Russia.
| | - A B Mostert
- Department of Physics and Centre for Integrative Semiconductor Materials, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EN, UK
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2
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Le Brun AP, Gilbert EP. Advances in sample environments for neutron scattering for colloid and interface science. Adv Colloid Interface Sci 2024; 327:103141. [PMID: 38631095 DOI: 10.1016/j.cis.2024.103141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/19/2024]
Abstract
This review describes recent advances in sample environments across the full complement of applicable neutron scattering techniques to colloid and interface science. Temperature, pressure, flow, tensile testing, ultrasound, chemical reactions, IR/visible/UV light, confinement, humidity and electric and magnetic field application, as well as tandem X-ray methods, are all addressed. Consideration for material choices in sample environments and data acquisition methods are also covered as well as discussion of current and potential future use of machine learning and artificial intelligence.
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Affiliation(s)
- Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Elliot Paul Gilbert
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234, Australia.
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3
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Le Brun AP, Huang TY, Pullen S, Nelson ARJ, Spedding J, Holt SA. Spatz: the time-of-flight neutron reflectometer with vertical sample geometry at the OPAL research reactor. J Appl Crystallogr 2023; 56:18-25. [PMID: 36777140 PMCID: PMC9901927 DOI: 10.1107/s160057672201086x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/12/2022] [Indexed: 12/23/2022] Open
Abstract
The Spatz neutron beam instrument is the second time-of-flight neutron reflectometer to be installed at the OPAL research reactor. The instrument was formerly the V18 BioRef reflectometer at the BER-II reactor in Berlin and was transferred to Australia in 2016. Subsequently the instrument was re-installed in the neutron guide hall of the OPAL reactor at the end position of the CG2B cold-neutron guide and recommissioned. The instrument performance has not been compromised by the move, with reflectivity achieved down to 10-7 and good counting statistics within a reasonable time frame using a wavelength range of 2-20 Å. Several different samples at the solid-air interface and the solid-liquid interface have been measured to demonstrate the instrument's capabilities.
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Affiliation(s)
- Anton P. Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Tzu-Yen Huang
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu, 30076, Taiwan
| | - Stewart Pullen
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Andrew R. J. Nelson
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - James Spedding
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - Stephen A. Holt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
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4
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Mostert AB. The importance of water content on the conductivity of biomaterials and bioelectronic devices. J Mater Chem B 2022; 10:7108-7121. [PMID: 35735112 DOI: 10.1039/d2tb00593j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Conductive biocompatible-, bioinspired- and biomaterials are increasing in importance, especially in bioelectronic applications where these materials are used in a variety of devices. Given the intended purpose of many of these devices is to interface with the human body, a pertinent issue is the effect of water from the environment on the electrical properties of the materials and devices. A researcher on biomaterials may currently not be aware, but the conductivity of these materials and device performances can be significantly altered with the presence of hydration in the environment. Examples will be given to highlight the problem that the conductivity of biomaterials can change by orders of magnitude depending on water content. Furthermore, case studies will be discussed in which control of the water content was key to understanding the underlying charge transport mechanism of conductive biomaterials. Examples of various devices and their response to hydration content will also be covered. Finally, this perspective will also mention the various methods of hydration control (including contrast studies) that can be used to perform careful work on conductive biomaterials and devices. Overall, water content should be considered an environmental variable as important as temperature to control for sound scientific investigation and to yield understanding of conductive biomaterials and bioelectronic devices.
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Affiliation(s)
- A Bernardus Mostert
- Department of Physics, Swansea University, Singleton Park, SA2, 8PP, Wales, UK.
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Büngeler A, Kollmann F, Huber K, Strube OI. Targeted Synthesis of the Type-A Particle Substructure from Enzymatically Produced Eumelanin. Biomacromolecules 2022; 23:1020-1029. [PMID: 34982545 PMCID: PMC8924864 DOI: 10.1021/acs.biomac.1c01390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Eumelanin exhibits a defined supramolecular buildup that is deprived of at least three distinct particle species. To enable the full potential of its promising material properties, access to all particle types is crucial. In this work, the first protocol for the synthesis of the intermediate type-A particles in pure and stable dispersion form is described. It is found that aggregation of type-A particles into the larger type-B variant can be inhibited by a strict pH control during the synthesis. The exact influence of pH on the supramolecular buildup is investigated via a combination of time-resolved light scattering, electron microscopy, and UV-vis spectroscopy. It is observed that a rapid buildup of type-B particles occurs without pH control and is generally dominant at lower pH values. At pH values above 6.2 however, type-A particles are gained, and no further aggregation occurs. Even more, lowering the pH of such a stable type-A dispersion at a later stage lifts the inhibition and again leads to the formation of larger particle species. The results confirm that it is easily possible to halt the aggregation of eumelanin substructures and to access them in the form of a stable dispersion. Moreover, a profound additional understanding of the supramolecular buildup is gained by the in-depth investigation of the pH influence.
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Affiliation(s)
- Anne Büngeler
- Institute for Chemical Engineering, University of Innsbruck, 6020 Innsbruck, Austria.,Biobased and Bioinspired Materials, Paderborn University, 33098 Paderborn, Germany
| | - Fabian Kollmann
- Department of Physical Chemistry, Paderborn University, 33098 Paderborn, Germany
| | - Klaus Huber
- Department of Physical Chemistry, Paderborn University, 33098 Paderborn, Germany
| | - Oliver I Strube
- Institute for Chemical Engineering, University of Innsbruck, 6020 Innsbruck, Austria.,Biobased and Bioinspired Materials, Paderborn University, 33098 Paderborn, Germany
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Cavaye H, Welbourn RJL, Gluschke JG, Hughes P, Nguyen KV, Micolich AP, Meredith P, Mostert AB. Systematic in situ hydration neutron reflectometry study on Nafion thin films. Phys Chem Chem Phys 2022; 24:28554-28563. [DOI: 10.1039/d2cp03067e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Nafion thin films continuously form an increasing number of lamellae layers (high Q peak) near a substrate surface with increasing hydration content, as opposed to exhibiting a phase transition like change.
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Affiliation(s)
- Hamish Cavaye
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot, OX11 0QX, UK
| | - Rebecca J. L. Welbourn
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot, OX11 0QX, UK
| | - Jan G. Gluschke
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
| | - Paul Hughes
- Centre for Nano Health, College of Engineering, Swansea University, Swansea SA2 8PP, UK
| | - Ky V. Nguyen
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
| | - Adam P. Micolich
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
| | - Paul Meredith
- Department of Physics, Swansea University, Singleton Park, SA2 8PP, Wales, UK
- School of Mathematics and Physics, University of Queensland, St Lucia Campus, Brisbane Queensland 4072, Australia
| | - A. Bernardus Mostert
- Department of Chemistry, Swansea University, Singleton Park, Swansea, SA2 8PP, UK
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Martinez-Gonzalez JA, Cavaye H, McGettrick JD, Meredith P, Motovilov KA, Mostert AB. Interfacial water morphology in hydrated melanin. SOFT MATTER 2021; 17:7940-7952. [PMID: 34378618 DOI: 10.1039/d1sm00777g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The importance of electrically functional biomaterials is increasing as researchers explore ways to utilise them in novel sensing capacities. It has been recognised that for many of these materials the state of hydration is a key parameter that can heavily affect the conductivity, particularly those that rely upon ionic or proton transport as a key mechanism. However, thus far little attention has been paid to the nature of the water morphology in the hydrated state and the concomitant ionic conductivity. Presented here is an inelastic neutron scattering (INS) experiment on hydrated eumelanin, a model bioelectronic material, in order to investigate its 'water morphology'. We develop a rigorous new methodology for performing hydration dependent INS experiments. We also model the eumelanin dry spectra with a minimalist approach whereas for higher hydration levels we are able to obtain difference spectra to extract out the water scattering signal. A key result is that the physi-sorbed water structure within eumelanin is dominated by interfacial water with the number of water layers between 3-5, and no bulk water. We also detect for the first time, the potential signatures for proton cations, most likely the Zundel ion, within a biopolymer/water system. These new signatures may be general for soft proton ionomer systems, if the systems are comprised of only interfacial water within their structure. The nature of the water morphology opens up new questions about the potential ionic charge transport mechanisms within hydrated bioelectronics materials.
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Affiliation(s)
- J A Martinez-Gonzalez
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot, OX11 0QX, UK
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9
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Mostert AB. Melanin, the What, the Why and the How: An Introductory Review for Materials Scientists Interested in Flexible and Versatile Polymers. Polymers (Basel) 2021; 13:1670. [PMID: 34065580 PMCID: PMC8161012 DOI: 10.3390/polym13101670] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 01/13/2023] Open
Abstract
Today, western society is facing challenges to create new medical technologies to service an aging population as well as the ever-increasing e-waste of electronic devices and sensors. A key solution to these challenges will be the use of biomaterials and biomimetic systems. One material that has been receiving serious attention for its biomedical and device applications is eumelanin. Eumelanin, or commonly known as melanin, is nature's brown-black pigment and is a poly-indolequinone biopolymer, which possess unique physical and chemical properties for material applications. Presented here is a review, aimed at polymer and other materials scientists, to introduce eumelanin as a potential material for research. Covered here are the chemical and physical structures of melanin, an overview of its unique physical and chemical properties, as well as a wide array of applications, but with an emphasis on device and sensing applications. The review is then finished by introducing interested readers to novel synthetic protocols and post synthesis fabrication techniques to enable a starting point for polymer research in this intriguing and complex material.
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Affiliation(s)
- A Bernardus Mostert
- Department of Chemistry, Swansea University, Singleton Park, Wales SA2 8PP, UK
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10
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Paulin JV, Batagin-Neto A, Meredith P, Graeff CFO, Mostert AB. Shedding Light on the Free Radical Nature of Sulfonated Melanins. J Phys Chem B 2020; 124:10365-10373. [PMID: 33153262 DOI: 10.1021/acs.jpcb.0c08097] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Melanin, an important class of natural pigment found in the human body, has stood out as a promising bioelectronic material due to its rather unique collection of electrical properties and biocompatibility. Among the available melanin derivatives, the sulfonated form has proven to not only be able to produce homogeneous device quality thin films with excellent adhesion, even on hydrophobic surfaces, but also to act as an ion to electron transducing element. It has recently been shown that the transport physics (and dominant carrier generation) may be related to a semiquinone free radical species in these materials. Hence, a better understanding of the paramagnetic properties of sulfonated derivatives could shed light on their charge transport behavior and thus enable improvement in regard to use in bioelectronics. Motivated by this question, in this work, different sulfonated melanin derivatives were investigated by hydration-controlled, continuous-wave X-band electron paramagnetic resonance spectroscopy and electronic structure calculations. Our results show that sulfonated melanin behaves similarly to non-functionalized melanin, but demonstrates a less pronounced response to humidity vis-à-vis standard melanin. We thus speculate on the structural and charge transport behavior in light of these differences with a view to further engineering structure-property relationships.
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Affiliation(s)
- J V Paulin
- School of Sciences, Postgraduate Program in Science and Technology of Materials (POSMAT), São Paulo State University (UNESP), Bauru, Brazil.,Department of Physics, Swansea University, Singleton Park, Swansea SA2 8PP, United Kingdom
| | - A Batagin-Neto
- School of Sciences, Postgraduate Program in Science and Technology of Materials (POSMAT), São Paulo State University (UNESP), Bauru, Brazil.,São Paulo State University (UNESP), Campus of Itapeva, Itapeva, Brazil
| | - P Meredith
- Department of Physics, Swansea University, Singleton Park, Swansea SA2 8PP, United Kingdom.,School of Mathematics and Physics, University of Queensland, St. Lucia Campus, Brisbane, Queensland 4072, Australia
| | - C F O Graeff
- School of Sciences, Postgraduate Program in Science and Technology of Materials (POSMAT), São Paulo State University (UNESP), Bauru, Brazil.,School of Sciences, Department of Physics, São Paulo State University (UNESP), Bauru, Brazil
| | - A B Mostert
- Department of Chemistry, Swansea University, Singleton Park, Swansea SA2 8PP, United Kingdom
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11
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Mostert AB, Rienecker SB, Sheliakina M, Zierep P, Hanson GR, Harmer JR, Schenk G, Meredith P. Engineering proton conductivity in melanin using metal doping. J Mater Chem B 2020; 8:8050-8060. [DOI: 10.1039/d0tb01390k] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The proton conductivity in the model bioelectronic material melanin, is increased via a unique doping strategy utilising the chelation of the transition metal ion copper II. We also propose a potential mechanism for future such ionic studies.
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Affiliation(s)
| | | | | | - Paul Zierep
- Institut für Physikalische Chemie
- Albert-Ludwigs-Universität
- Freiburg
- Germany
| | - Graeme R. Hanson
- Centre of Advanced Imaging
- University of Queensland
- St. Lucia
- Australia
| | - Jeffrey R. Harmer
- Centre of Advanced Imaging
- University of Queensland
- St. Lucia
- Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences
- University of Queensland
- St. Lucia
- Australia
| | - Paul Meredith
- School of Mathematics and Physics
- University of Queensland
- St. Lucia
- Australia
- Department of Physics
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12
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Lee C, Jeon D, Bae S, Kim H, Han Y, Lee YW, Ryu J. Semiconducting Synthetic Melanin-Based Organic/Inorganic Hybrid Photoanodes for Solar Water Oxidation. CHEMSUSCHEM 2018; 11:3534-3541. [PMID: 29979491 DOI: 10.1002/cssc.201801135] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 06/09/2018] [Indexed: 06/08/2023]
Abstract
We report the development of semiconducting melanin-based organic/inorganic hybrid photoanodes for solar water oxidation. Synthetic melanin thin-film incorporating polyoxometalate (POM) water oxidation catalysts (WOCs) are readily deposited on the surface of various n-type inorganic semiconductors (e.g., Fe2 O3 , BiVO4 , and TiO2 ) by electropolymerization. The deposition of melanin and POM hybrid (MP) thin-film results in the remarkably improved performance of an underlying semiconductor photoanode for solar water oxidation with a significantly increased photocurrent density and decreased onset potential for water oxidation through the formation of a melanin-based p-n heterojunction structure. We believe that this study can provide insights into the design and fabrication of various melanin-based optoelectronic devices by utilizing its unique physicochemical properties.
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Affiliation(s)
- Cheolmin Lee
- Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 44919, Republic of Korea
| | - Dasom Jeon
- Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 44919, Republic of Korea
| | - Sanghyun Bae
- Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 44919, Republic of Korea
| | - Hyunwoo Kim
- Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 44919, Republic of Korea
| | - Yujin Han
- Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 44919, Republic of Korea
| | - Yang Woo Lee
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Republic of Korea
| | - Jungki Ryu
- Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan, 44919, Republic of Korea
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Büngeler A, Hämisch B, Strube OI. The Supramolecular Buildup of Eumelanin: Structures, Mechanisms, Controllability. Int J Mol Sci 2017; 18:E1901. [PMID: 28878140 PMCID: PMC5618550 DOI: 10.3390/ijms18091901] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 08/29/2017] [Accepted: 08/29/2017] [Indexed: 01/07/2023] Open
Abstract
Research on the supramolecular buildup of eumelanin has gained high momentum in the last years. Several new aspects regarding the involved structures and mechanisms have been established, which has led to a better understanding of the entire process. This review intends to provide a clearly laid-out summary of previous and new findings regarding structures, mechanisms, and controllability. With respect to materials applications, the aspect of controllability is of supreme importance. A focus of this review is therefore set on a novel method with high potential for specific synthesis of various, isolated particle morphologies. Finally, open questions and possibilities for their elucidation are discussed.
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Affiliation(s)
- Anne Büngeler
- Biobased and Bioinspired Materials, Department of Chemistry, Paderborn University, 33098 Paderborn, Germany.
| | - Benjamin Hämisch
- Department of Physical Chemistry, Paderborn University, 33098 Paderborn, Germany.
| | - Oliver I Strube
- Biobased and Bioinspired Materials, Department of Chemistry, Paderborn University, 33098 Paderborn, Germany.
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