Nanostructured PEDOT Coatings for Electrode–Neuron Integration

Abstract

Neural electrodes have been developed for the diagnosis and treatment of stroke, sensory deficits, and neurological disorders based on the electrical stimulation of nerve tissue and recording of neural electrical activity. A low interface impedance and large active surface area for charge transfer and intimate contact between neurons and the electrode are critical to obtain high-quality neural signal and effective stimulation without causing damage to both tissue and electrode. In this study, a nanostructured poly(3,4ethylenedioxythiophene) (PEDOT) coating with lots of long protrusions was created via a one-step electrochemical polymerization from a dichloromethane solution without any rigid or soft templates. The nanostructures on the PEDOT coating were basically formed by intertwined PEDOT nanofibers, which further enhanced the active surface area. The fuzzy PEDOT-modified microelectrodes exhibited an impedance as low as 1 kΩ at 1 kHz, which is much lower than those produced from aqueous 3,4-ethylenedioxythiophene (EDOT) solution, and it was comparable with PEDOT films or composites created from/ with template materials. Also, more than 150 times larger charge storage capacity density was obtained compared to the unmodified microelectrode. An in vitro biocompatibility test performed on PC12 cells and primary cells suggested that the PEDOT coatings support cell adhesion, growth, and neurite extension. These results suggest the great potential of the nanostructured PEDOT coating as an electroactive and biosafe intimate contact between the implanted neural electrode and neurons.

Implantable neural electrodes: from preparation optimization to application

“…For the use of specific materials (such as PEDOT:PSS and CNT, silk fibroin composite, etc.) or special structures to prepare nerve electrodes that can improve neural signal transmission while supporting neuronal elongation and cell adhesion, 79,181,182 some adhesion and proliferation tests will be conducted on nerve cells and electrodes. Combined with the use of scanning electron micrographs (SEM) to characterize the electrode morphology, it can more effectively display the impact of the material surface on cells.…”

Recent advances in the aqueous applications of PEDOT

“… 51 This highlights that considering nanostructures of CPs such as PEDOT is beneficial for biological applications. Zhang et al 52 fabricated electrochemical polymerised PEDOT:PF 6 with intertwined nanofibers. These nanostructured PEDOT materials displayed desirable electrical properties (×150 higher charge storage capacity, ×800 lower impedance, compared to the unmodified electrode) with appropriate in vitro biocompatibility and nontoxicity.…”

“…Ultimately the nanostructured PEDOT led to formation of a network of neurites that were also longer and larger in number. 52 An alternative method to achieve desirable nanostructure was presented by Richardson-Burns et al 53 with electropolymerised PEDOT:PSS around neurons which were subsequently removed using enzymatic and mechanical disruption. The creation of PEDOT:PSS with nanoscale cell-shaped holes and imprints showed good performance when re-seeded with SY5Y cells (which showed preference for adhering to regions where the neurons once were).…”

Tuning the electrical and magnetic properties in multifunctional composite materials based on the PEDOT:DBS conducting polymer and magnetite nanoparticles

“…[1][2][3][4][5][6] Due to these properties, PEDOT has been proposed for several applications, including electrochromic and bioelectronic devices, as a catalyst support, in electrode-neuron integration, artificial muscles, supercapacitors, and biosensors. 1,[6][7][8][9][10][11] On the other hand, iron oxide nanoparticles, in particular superparamagnetic Fe 3 O 4 , have shown versatile applications in different fields, for example in magnetic storage, magnetic resonance imaging (MRI), environmental remediation, magnetic hyperthermia, drug delivery, and magneto-optical devices. [12][13][14][15][16][17] Therefore, the combination of MNP and a conducting polymer allows controlling the chemical and physical properties, giving rise to hybrid materials with enhanced physicochemical properties, which can be tuned by varying, for example, the composition.…”