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Our long term goal is to develop new conjugated molecules and polymers with unique properties that will enable significant advances in the growing fields of organic electronics and bioelectronics. Since their discovery, conjugated polymers have attracted considerable attention from scientists and have become a key factor to the growing organic electronics and bioelectronics industries. Due to their conjugated backbone, theses polymers are organic semiconductors that can be utilized in applications including photovoltaics, field-effect transistors, light-emitting diodes, electrochromics, thermoelectrics, light detectors, antistatic coating, batteries, actuators and biosensors. Unlike their inorganic counterpart, they can be solution-processed using established printing technologies to yield lightweight, flexible functional thin films, allowing for low-cost and largedih area electronic devices. In order to meet this country’s technology and energy requirements, there is a critical need to design and synthesize high performance conjugated polymers that are robust and have tunable optical (light absorption and emission), electrical (high charge mobility, ionic and electrical conductivities) and physical properties (morphology and film-forming properties). Moreover, most of the conjugated polymers are derived from petroleum-based starting materials. As we shift from large consumption of oil, these feeder chemicals will become limited. Thus, it would be advantageous to seek alternative sources for building blocks to develop new organic semiconductors. In addition, it would be desirable to have more biocompatible materials for biomedical and bioelectronics applications.

In terms of chemical and functional diversity, nature is a great source of new building blocks for bioinspired organic semiconductors. One such inspiration is the “biopolymer”, melanin which is a class of naturally occurring pigment-containing indole units and other intermediate products derived from the oxidation of tyrosine. Melanin is one of the most primitive pigments occurs in in living organisms and is found several places in the human body, including skin, hair, ears, brains and eyes. It acts as an exceptional photoprotectant in the human body. There are three major types: eumelanin (black-brown), pheomelanin (brown-red) and neuromelanin, with eumelanin being the most predominant. Eumelanin is the black-brown variety of melanin and exist as a heterogeneous network, formed by the oxidative polymerization of two monomers namely 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) (Figure 1). Extensive research has been done on the optical, electronic, physical, metal chelating, and structural properties of natural and synthetic eumelanin. The few examples listed above demonstrate the wide range of promise for the field of applications for eumelanin-based materials. However, these eumelanin materials have poor solubility, produce thin, brittle films with poor morphologies and are mostly polydispersed nanoparticles. Thus such properties are not well-suited for analysis and fabrication of organic electronic devices.