Dataset Information

Evaluation of poly(3,4-ethylenedioxythiophene)/carbon nanotube neural electrode coatings for stimulation in the dorsal root ganglion.

ABSTRACT: The dorsal root ganglion is an attractive target for implanting neural electrode arrays that restore sensory function or provide therapy via stimulation. However, penetrating microelectrodes designed for these applications are small and deliver low currents. For long-term performance of microstimulation devices, novel coating materials are needed in part to decrease impedance values at the electrode-tissue interface and to increase charge storage capacity.Conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and multi-wall carbon nanotubes (CNTs) were coated on the electrode surface and doped with the anti-inflammatory drug, dexamethasone. Electrode characteristics and the tissue reaction around neural electrodes as a result of stimulation, coating and drug release were characterized. Hematoxylin and eosin staining along with antibodies recognizing Iba1 (microglia/macrophages), NF200 (neuronal axons), NeuN (neurons), vimentin (fibroblasts), caspase-3 (cell death) and L1 (neural cell adhesion molecule) were used. Quantitative image analyses were performed using MATLAB.Our results indicate that coated microelectrodes have lower in vitro and in vivo impedance values. Significantly less neuronal death/damage was observed with coated electrodes as compared to non-coated controls. The inflammatory response with the PEDOT/CNT-coated electrodes was also reduced.This study is the first to report on the utility of these coatings in stimulation applications. Our results indicate PEDOT/CNT coatings may be valuable additions to implantable electrodes used as therapeutic modalities.

SUBMITTER: Kolarcik CL

PROVIDER: S-EPMC4433052 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

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Evaluation of poly(3,4-ethylenedioxythiophene)/carbon nanotube neural electrode coatings for stimulation in the dorsal root ganglion.

Kolarcik Christi L CL Catt Kasey K Rost Erika E Albrecht Ingrid N IN Bourbeau Dennis D Du Zhanhong Z Kozai Takashi D Y TD Luo Xiliang X Weber Douglas J DJ Cui X Tracy XT

Journal of neural engineering 20141208 1

<h4>Objective</h4>The dorsal root ganglion is an attractive target for implanting neural electrode arrays that restore sensory function or provide therapy via stimulation. However, penetrating microelectrodes designed for these applications are small and deliver low currents. For long-term performance of microstimulation devices, novel coating materials are needed in part to decrease impedance values at the electrode-tissue interface and to increase charge storage capacity.<h4>Approach</h4>Condu ...[more]

PMID: 25485675

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Project description:Electrical microstimulation has shown promise in restoring neural deficits in humans. Electrodes coated with materials like the conducting polymer poly(3,4‐ethylenedioxythiophene) doped with acid‐functionalized carbon nanotubes (PEDOT/CNTs, or PC) exhibit superior charge injection than traditional metals like platinum. However, the stimulation performance of PC remains to be fully characterized. Advanced imaging techniques and transgenic tools allow for real‐time observations of neural activity in vivo. Herein, microelectrodes coated with PC and iridium oxide (IrOx) (a commonly used high‐charge‐injection material) are implanted in GCaMP6s mice and electrical stimulation is applied while imaging neuronal calcium responses. Results show that PC‐coated electrodes stimulate more intense and broader GCaMP responses than IrOx. Two‐photon microscopy reveals that PC‐coated electrodes activate significantly more neuronal soma and neuropil than IrOx‐coated electrodes in constant‐voltage stimulation and significantly more neuronal soma in constant‐current stimulation. Furthermore, with the same injected charge, both materials activate more spatially confined neural elements with shorter pulses than longer pulses, providing a means to tune stimulation selectivity. Finite element analyses reveal that the PC coating creates a denser and nonuniform electric field, increasing the likelihood of activating nearby neural elements. PC coating can significantly improve energy efficiency for electrical stimulation applications. The stimulation performance of two high‐charge‐injection materials poly(3,4‐ethylenedioxythiophene) doped with acid‐functionalized carbon nanotube (PEDOT/CNT) and iridium oxide is examined. In vivo imaging results show that PEDOT/CNT is a more energy‐efficient material for cortical activation. In addition, for both materials, shorter stimulation pulses activate more spatially distinct neural elements than longer pulses, providing a means to tune stimulation selectivity.© 2021 WILEY‐VCH GmbH

Project description:Magnesium (Mg) is a promising biodegradable implant material because of its appropriate mechanical properties and safe degradation products. However, in vivo corrosion speed and hydrogen gas production need to be controlled for uses in biomedical applications. Here we report the development of a conducting polymer 3,4-ethylenedioxythiphene (PEDOT) and graphene oxide (GO) composite coating as a corrosion control layer. PEDOT/GO was electropolymerized on Mg samples in ethanol media. The coated Mg samples were subjected to various corrosion tests. The PEDOT/GO coating significantly reduced the rate of corrosion as evidenced by lower Mg ion concentration and pH of the corrosion media. In addition, the coating decreased the evolved hydrogen. Electrochemical analysis of the corroding samples showed more positive corrosion potential, a decreased corrosion current, and an increase in the polarization resistance. PEDOT/GO corrosion protection is attributed to three factors; an initial passive layer preventing solution ingress, buildup of negative charges in the film, and formation of corrosion protective Mg phosphate layer through redox coupling with Mg corrosion. To explore the biocompatibility of the coated implants in vitro, corrosion media from PEDOT/GO coated or uncoated Mg samples were exposed to cultured neurons where PEDOT/GO coated samples showed decreased toxicity. These results suggest that PEDOT/GO coating will be an effective treatment for controlling corrosion of Mg based medical implants.Coating Mg substrates with a PEDOT/GO composite coating showed a significant decrease in corrosion rate. While conducting polymer coatings have been used to prevent corrosion on various metals, there has been little work on the use of these coatings for Mg. Additionally, to our knowledge, there has not been a report of the combined used of conducting polymer and GO as a corrosion control layer. Corrosion control is attributed to an initial barrier layer followed by electrochemical coupling of the PEDOT/GO coating with the substrate to facilitate the formation of a protective phosphate layer. This coupling also resulted in a decrease in hydrogen produced during corrosion, which could further improve the host tissue integration of Mg implants. This work elaborates on the potential for electroactive polymers to serve as corrosion control methods.

Dataset Information

Evaluation of poly(3,4-ethylenedioxythiophene)/carbon nanotube neural electrode coatings for stimulation in the dorsal root ganglion.

Publications

Evaluation of poly(3,4-ethylenedioxythiophene)/carbon nanotube neural electrode coatings for stimulation in the dorsal root ganglion.

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