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1

Department of Bioengineering, University of Pittsburgh, 5056 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15213, USA

2

Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15260, USA

3

McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA

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NeuroTech Center of the University of Pittsburgh Brain Institute, Pittsburgh, PA 15260, USA





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Author to whom correspondence should be addressed.



Academic Editor: Hargsoon Yoon

Abstract Neural electrodes hold tremendous potential for improving understanding of brain function and restoring lost neurological functions. Multi-walled carbon nanotube MWCNT and dexamethasone Dex-doped poly3,4-ethylenedioxythiophene PEDOT coatings have shown promise to improve chronic neural electrode performance. Here, we employ electrochemical techniques to characterize the coating in vivo. Coated and uncoated electrode arrays were implanted into rat visual cortex and subjected to daily cyclic voltammetry CV and electrochemical impedance spectroscopy EIS for 11 days. Coated electrodes experienced a significant decrease in 1 kHz impedance within the first two days of implantation followed by an increase between days 4 and 7. Equivalent circuit analysis showed that the impedance increase is the result of surface capacitance reduction, likely due to protein and cellular processes encapsulating the porous coating. Coating’s charge storage capacity remained consistently higher than uncoated electrodes, demonstrating its in vivo electrochemical stability. To decouple the PEDOT-MWCNT material property changes from the tissue response, in vitro characterization was conducted by soaking the coated electrodes in PBS for 11 days. Some coated electrodes exhibited steady impedance while others exhibiting large increases associated with large decreases in charge storage capacity suggesting delamination in PBS. This was not observed in vivo, as scanning electron microscopy of explants verified the integrity of the coating with no sign of delamination or cracking. Despite the impedance increase, coated electrodes successfully recorded neural activity throughout the implantation period. View Full-Text

Keywords: interface; neural prosthesis; drug release; controlled drug release; electroactive polymer; nanocomposite interface; neural prosthesis; drug release; controlled drug release; electroactive polymer; nanocomposite





Autor: Nicolas A. Alba 1,2,3, Zhanhong J. Du 1,2,3, Kasey A. Catt 1, Takashi D. Y. Kozai 1,2,3,4 and X. Tracy Cui 1,2,3,*

Fuente: http://mdpi.com/



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