Fractal form PEDOT/Au assemblies as thin-film neural interface materials

Abstract

Electrically conducting polymer formulations have emerged as promising approaches for the development of interfaces and scaffolds in neural engineering, facilitating the development of physicochemically modified constructs capable of cell stimulation through electrical and ionic charge transfer. In particular, topographically functionalized or neuromorphic materials are able to guide the growth of axons and promote enhanced interfacing with neuroelectrodes in vitro. In this study, we present a novel method for the formation of conducting polymer/gold assemblies via a combinational sputter and spin coating technique. The resulting multilayered PEDOT/Au substrates possessed enhanced electrochemical properties as a function of the number of deposited organic/inorganic layers. It was observed that through subsequent electrochemical conditioning it was possible to form neuromorphic fractal-like assemblies of gold particles, which significantly impacted on the electrochemical characteristics of the PEDOT/Au films. PEDOT/Au assemblies were observed to possess unique topographical features, advantageous charge storage capacity (34.9 ± 2.6 mC cm) and low electrical impedance (30 ± 2 Ω at 1 kHz). Furthermore, PEDOT/Au assemblies were observed to facilitate the outgrowth of neurites in a mixed ventral mesencephalon cell population and promotean increase in the neurons/astrocytes ratio relative to all experimental groups, indicating PEDOT/Au biomimetic neuromorphic assemblies as promising materials in engineering electrically conductive neural interface systems.

The Synergistic Effects of Gold Particles and Dexamethasone on the Electrochemical and Biological Performance of PEDOT Neural Interfaces

“…The cytocompatibility of PEDOT, PEDOT/Au, PEDOT-Dex and PEDOT-Dex/Au was determined with respect to primary cultures of a mixed neural population obtained from the mesencephalon of embryonic Sprague–Dawley, and cultured for 7 days, as described previously [22,23]. All experiments were performed in accordance with the EU guidelines (2010/63/UE) and were approved by Health Products Regulatory Authority (AE19125/I179) and the local authority veterinary service.…”

“…Every effort was made to minimize animal suffering and to reduce the number of animals used. The indirect double-immunofluorescent labelling was applied to visualize neuron and astrocyte cell populations and an Olympus Fluoview 1000 Confocal Microscope (Olympus, Tokyo, Japan) was used to obtain fluorescent images [23,24]. Cell density was analyzed by counting the number of nuclei corresponding to neurons and astrocytes in an area of 211.97 μm × 211.97 μm in at least 20 random images taken from test and control groups [24].…”

Analysis of a poly(ε-decalactone)/silver nanowire composite as an electrically conducting neural interface biomaterial

“…The embryos were obtained by laparotomy from time-mated female Sprague-Dawley rats delivered by Charles River Laboratories. After arrival and 1 day accommodation period, the rats were decapitated under terminal anaesthesia induced by the inhalation of isoflurane [ 17 , 51 ]. Neurons and astrocyte cell populations were visualized through the indirect double-immunofluorescent labelling [ 17 , 19 ], with the use of an Olympus Fluoview 1000 Confocal Microscope (scan size of 1024 × 1024 at a ratio 1:1 and 60× magnification).…”

“…After arrival and 1 day accommodation period, the rats were decapitated under terminal anaesthesia induced by the inhalation of isoflurane [ 17 , 51 ]. Neurons and astrocyte cell populations were visualized through the indirect double-immunofluorescent labelling [ 17 , 19 ], with the use of an Olympus Fluoview 1000 Confocal Microscope (scan size of 1024 × 1024 at a ratio 1:1 and 60× magnification). To analyse cell density, the number of nuclei corresponding to neurons and astrocytes were counted in an area of 211.97 μm × 211.97 μm in at least 20 random images taken from test and control groups [ 19 ].…”

“…Critically, peri-implant gliosis has been shown to significantly reduce chronic neuroelectrode functionality in vivo [ 15 ]. It follows that metal electrodes can be functionalized with biocompatible organic coatings with an aim to provide a biointerface with tailorable electromechanical properties that promote electrode integration as well as chronic functionality [ 16 , 17 ]. Because the functional coating must be both biocompatible and also electrically conducting, the range of biomaterials that can be used in this specific application is limited to either intrinsically conducting polymers, such as polypyrrole [ 18 ] or poly(3,4-ethylenedioxythiophene) [ 16 ] or composite materials formed from a conducting filler (carbon nanotubes, metal particles, etc) and biocompatible polymer matrix [ 19 ].…”