Honors Theses and Capstones

Title

Electrochemical and Spectroscopic Study of Peptide-template Melanins

Date of Award

Spring 2018

Project Type

Senior Honors Thesis

College or School

CEPS

Department

Chemical Engineering

Program or Major

Bioengineering

Degree Name

Bachelor of Science

First Advisor

Young Jo Kim

Abstract

Melanins are organic polymers made up of 5,6-dihydroxyindole carboxylic acid (DHICA) and 5,6-dihydroxyindole (DHI). Biochemical systems synthesize melanins through a complex reaction pathway. Previous research exhibited that naturally-occurring melanins (NatMel) and their synthetic analogues (SynMel) can potentially serve as electrode materials for aqueous charge storage devices. Small surface area creates technical challenges for these melanins as charge storage materials. This research herein demonstrates that the structure of melanins can affect the charge storage capacities of monovalent Na+cations and divalent Mg2+ cations. 2-D sheet-like peptide melanins (PepMel) were synthesized into tripeptides consisting of aspartic acid (D), phenylalanine (F), and tyrosine (Y) through a heating and cooling process. Tyrosinase from Agaricus bisporus was used to oxidize the Y residues and initiate polymerization of the tripeptides into molecules with 2-D planar morphologies. Structural analysis of NatMel, SynMel, and PepMel was performed with scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area measurement. Melanins were electrochemically examined by cyclic voltammetry and chronoamperometry followed by chemical analysis using Raman spectroscopy.

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