Karl W. and Renate Böer Professor of Materials Science and Engineering, The University of Delaware Supervisors: Edwin Thomas, Gerhard Wegner, and Kenncorwin Gardner Phone: (302) 831-2062 Address: 201C DuPont Hall
Newark, DE 19716
Natural melanins are biocompatible conductors with versatile functionalities. Here, we report fab... more Natural melanins are biocompatible conductors with versatile functionalities. Here, we report fabrication of multifunctional poly(vinyl alcohol)/melanin nanocomposites by layer-by-layer (LBL) assembly using melanin nanoparticles (MNPs) directly extracted from sepia officinalis inks. The LBL assembly offers facile manipulation of nanotextures as well as nm-thickness control of the macroscale film by varying solvent qualities. The time-resolved absorption was monitored during the process and quantitatively studied by fractal dimension and lacunarity analysis. The capability of nanoarchitecturing provides confirmation of complete monolayer formation and leads to tunable iridescent reflective colors of the MNP films. In addition, the MNP films have durable electrochemical conductivities as evidenced by enhanced charge storage capacities for 1000 cycles. Moreover, the MNP covered ITO (indium tin oxide) substrates significantly reduced secretion of inflammatory cytokines, TNF-α, by raw 26...
We have developed a patterning procedure based on selective ablation using interference patterns ... more We have developed a patterning procedure based on selective ablation using interference patterns with ns-laser pulses to fabricate periodic arrays on large areas of poly (3, 4-ethylene dioxythiophene)-poly (4-styrene sulfonic acid)(PEDOT-PSS) thin films over a metallic gold–palladium layer. Single pulse laser-ablation experiments were performed to study the ablation characteristics of the thin films as a function of the film thickness. The ablation threshold fluence of the PEDOT-PSS films was found to be dependent on ...
Poly(3,4-ethylene dioxythiophene) (PEDOT) is a chemically stable, conjugated polymer that is of c... more Poly(3,4-ethylene dioxythiophene) (PEDOT) is a chemically stable, conjugated polymer that is of considerable interest for a variety of applications including coatings for interfacing electronic biomedical devices with living tissue. Here, we describe recent work from our laboratory and elsewhere to investigate the morphology of PEDOT in the solid state. We discuss the importance of oxidative chemical and electrochemical polymerization, as
Recently, a significant amount of effort has been dedicated to understanding factors that influen... more Recently, a significant amount of effort has been dedicated to understanding factors that influence the functionality of bio-electronic sensors and to development of novel coating technologies for modifying biosensor surfaces. Due to its well-known biocompatibility, alginate hydrogel (HG) has been used as a coating material on neural electrodes for promoting intimate cellular integration, providing a scaffold for local drug delivery, and creating a mechanical buffer between hard electrodes and the soft tissues of the central nervous system. However, neural signal recordings using HG-coated electrodes in animal models are still poorly evaluated. Here, we investigated the effect of the proximity of source neurons around the electrode sites using HG coatings with various thicknesses deposited on microfabricated electrodes, implanted in auditory cortex of guinea pigs. We also evaluated the role of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) in improving the recording functionality of the HG-coated neural electrodes. A significant loss in recording functionality was observed with thicker HG coatings, as determined by the number of clearly detectable units (30% with 80 microm thick coatings) and average signal-to-noise ratios (3.91 with 80 microm thick coatings). However, deposition of the conducting polymer PEDOT on the electrode sites restored the lost functionality of the electrodes caused by the HG coatings (30 microm). These conducting polymer/HG coatings have the potential to improve long-term performance of the neural electrodes not only by improving the electrode biocompatibility but also by facilitating more efficient signal transmission.
Natural melanins are biocompatible conductors with versatile functionalities. Here, we report fab... more Natural melanins are biocompatible conductors with versatile functionalities. Here, we report fabrication of multifunctional poly(vinyl alcohol)/melanin nanocomposites by layer-by-layer (LBL) assembly using melanin nanoparticles (MNPs) directly extracted from sepia officinalis inks. The LBL assembly offers facile manipulation of nanotextures as well as nm-thickness control of the macroscale film by varying solvent qualities. The time-resolved absorption was monitored during the process and quantitatively studied by fractal dimension and lacunarity analysis. The capability of nanoarchitecturing provides confirmation of complete monolayer formation and leads to tunable iridescent reflective colors of the MNP films. In addition, the MNP films have durable electrochemical conductivities as evidenced by enhanced charge storage capacities for 1000 cycles. Moreover, the MNP covered ITO (indium tin oxide) substrates significantly reduced secretion of inflammatory cytokines, TNF-α, by raw 26...
We have developed a patterning procedure based on selective ablation using interference patterns ... more We have developed a patterning procedure based on selective ablation using interference patterns with ns-laser pulses to fabricate periodic arrays on large areas of poly (3, 4-ethylene dioxythiophene)-poly (4-styrene sulfonic acid)(PEDOT-PSS) thin films over a metallic gold–palladium layer. Single pulse laser-ablation experiments were performed to study the ablation characteristics of the thin films as a function of the film thickness. The ablation threshold fluence of the PEDOT-PSS films was found to be dependent on ...
Poly(3,4-ethylene dioxythiophene) (PEDOT) is a chemically stable, conjugated polymer that is of c... more Poly(3,4-ethylene dioxythiophene) (PEDOT) is a chemically stable, conjugated polymer that is of considerable interest for a variety of applications including coatings for interfacing electronic biomedical devices with living tissue. Here, we describe recent work from our laboratory and elsewhere to investigate the morphology of PEDOT in the solid state. We discuss the importance of oxidative chemical and electrochemical polymerization, as
Recently, a significant amount of effort has been dedicated to understanding factors that influen... more Recently, a significant amount of effort has been dedicated to understanding factors that influence the functionality of bio-electronic sensors and to development of novel coating technologies for modifying biosensor surfaces. Due to its well-known biocompatibility, alginate hydrogel (HG) has been used as a coating material on neural electrodes for promoting intimate cellular integration, providing a scaffold for local drug delivery, and creating a mechanical buffer between hard electrodes and the soft tissues of the central nervous system. However, neural signal recordings using HG-coated electrodes in animal models are still poorly evaluated. Here, we investigated the effect of the proximity of source neurons around the electrode sites using HG coatings with various thicknesses deposited on microfabricated electrodes, implanted in auditory cortex of guinea pigs. We also evaluated the role of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) in improving the recording functionality of the HG-coated neural electrodes. A significant loss in recording functionality was observed with thicker HG coatings, as determined by the number of clearly detectable units (30% with 80 microm thick coatings) and average signal-to-noise ratios (3.91 with 80 microm thick coatings). However, deposition of the conducting polymer PEDOT on the electrode sites restored the lost functionality of the electrodes caused by the HG coatings (30 microm). These conducting polymer/HG coatings have the potential to improve long-term performance of the neural electrodes not only by improving the electrode biocompatibility but also by facilitating more efficient signal transmission.
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