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Abstract The development of electronic devices from naturally derived materials is of enormous scientific interest. Melanin, a dark protective pigment ubiquitous in living creatures, may be particularly valuable because of its ability to conduct charges both electronically and ionically. However, device applications are severely hindered by its relatively poor electrical properties. Here, the facile preparation of conductive melanin composites is reported in which melanin nanoparticles (MNPs), directly extracted from squid inks, form electrically continuous junctions by tight clustering in a poly(vinyl alcohol) (PVA) matrix. Prepared as freestanding films and patterned microstructures by a series of precipitation, dry casting, and post‐thermal annealing steps, the percolated composites show electrical conductivities as high as 1.17 ± 0.13 S cm⁻¹at room temperature, which is the best performance yet obtained with biologically‐derived nanoparticles. Furthermore, the biodegradability of the MNP/PVA composites is confirmed through appetitive ingestion byZophobas morioslarvae (superworms). This discovery for preparing versatile biocomposites suggests new opportunities in functional material selections for the emerging applications of implantable, edible, green bioelectronics. 

We have used Liquid-Phase Transmission Electron Microscopy (LPTEM) to directly image the fundamental processes occurring at the electrode-solution interface during electrochemical deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) from an isotropic 3,4-ethylenedioxythiophene (EDOT) monomer solution. We clearly observed the various stages of the electrodeposition process including the initial nucleation of liquid-like EDOT oligomer droplets onto the glassy carbon working electrode and then the merging, coalesce and growth in size and thickness of these droplets into solid, stable, and dark PEDOT conjugated polymer films. We also used correlative transmitted light optical microscopy to study this process, revealing the change in color of the translucent clusters to the dark polymer film caused by the increase in conjugation length. From our studies we have been able to correlate specific observations of local structure and dynamics to the liquid-like (EDOT oligomer) droplets and solid-like (PEDOT polymer) films including their mobility, mass thickness, edge roughness, size, circularity, and optical absorption. 

ABSTRACT We continue to investigate the design, synthesis, and characterization of electrically and ionically active conjugated polythiophene copolymers for integrating a variety of biomedical devices with living tissue. This paper will describe some of our most recent results, including the development of several new monomers that can tailor the surface chemistry, adhesion, and biointegration of these materials with neural cells. Our efforts have focused on copolymers of 3,4 ethylenedioxythiophene (EDOT), functionalized variants of EDOT (including EDOT-acid and the trifunctional EPh), and dopamine (DOPA). The resulting PEDOT-based copolymers have electrical, optical, mechanical, and adhesive properties that can be precisely tailored by fine tuning the chemical composition and structure. Here we present results on EDOT-dopamine bifunctional monomers and their corresponding polymers. We discuss the design and synthesis of an EDOT-cholesterol that combines the thiophene with a biological moiety known to exhibit surface-active behaviour. We will also introduce EDOT-aldehyde and EDOT-maleimide monomers and show how they can be used as the starting point for a wide variety of functionalized monomers and polymers.