title: Evidence of Porphyrin-Like Structures in Natural Melanin Pigments Using Electrochemical Fingerprinting.
abstract: Eumelanins are extended heterogeneous biopolymers composed of molecular subunits with ambiguous macromolecular topology. Here, an electrochemical fingerprinting technique is described, which suggests that natural eumelanin pigments contain indole-based tetramers that are arranged into porphyrin-like domains. Spectroscopy and density functional theory calculations suggest that sodium ions undergo occupancy-dependent stepwise insertion into the core of porphyrin-like tetramers in natural eumelanins at discrete potentials.
authors.affiliation: Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.
authors.forename: Young Jo
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.|Institute for Combustion Technology, RWTH, Aachen, 52062, Germany.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Khetan
authors.affiliation: Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.affiliation: Department of Chemistry, University of Oregon, Eugene, OR, 97403, USA.
authors.forename: Sang-Eun
authors.initials: SE
authors.lastname: Chun
authors.affiliation: Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.
authors.forename: Venkatasubramanian
authors.initials: V
authors.lastname: Viswanathan
authors.affiliation: Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.
authors.forename: Jay F
authors.initials: JF
authors.lastname: Whitacre
authors.affiliation: Department of Materials Science and Engineering, Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.|McGowan Institute of Regenerative Medicine, 450 Technology Drive, Suite 300, Pittsburgh, PA, 15219, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Bettinger
mesh_terms: D055664:Electrochemical Techniques / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008543:Melanins / Q000737:chemistry*; D011166:Porphyrins / Q000032:analysis* / Q000737:chemistry*
chemical_list: D046911:Macromolecular Substances; D008543:Melanins; D011166:Porphyrins
keywords: biopolymers; cathodes; electrochemical storage; melanin; mesoscale