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

Abstract

Although neural devices have shown efficacy in the treatment of neurodegenerative diseases, their functionality is limited by the inflammatory state and glial scar formation associated with chronic implantation. The aim of this study was to investigate neural electrode performance following functionalization with an anti-inflammatory coating derived from a conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) matrix doped with dexamethasone (Dex) and decorated with Au particles. Pristine PEDOT, PEDOT-Dex and their gold-decorated analogues (PEDOT/Au and PEDOT-Dex/Au) were formulated by electrochemical deposition and characterized with respect to electrode electrochemical properties, surface morphology and biocompatibility towards primary neural cells. Through a process of gold deposition, it was possible to eliminate the initial burst release observed in PEDOT-Dex and maintain a stable, stepwise increase in Dex elution over 7 days. The released amounts of Dex exceeded the concentrations considered as therapeutic for both PEDOT-Dex and PEDOT-Dex/Au. The results clearly indicated that the presence of either Dex or Au particles facilitated the outgrowth of neurites. Finally, it was shown that the application of composite materials, such as PEDOT-Dex/Au, is an efficient way to improve the efficacy of neural interfaces in vitro.

Gold nanostructures: synthesis, properties, and neurological applications

“…595 Another exciting approach involves the addition of AuNPs to conductive polymers to improve their electrochemical properties for neural stimulation, recording, and even electrochemical detection of biomolecules such as glucose. 593,596…”

Overoxidized poly(3,4-ethylenedioxythiophene)–gold nanoparticles–graphene-modified electrode for the simultaneous detection of dopamine and uric acid in the presence of ascorbic acid

“…Metal nanoparticles, especially gold nanoparticles (AuNPs), have been extensively integrated into PEDOT materials because of their high affinity toward sulfur atoms and their commendable, high specific surface area, catalytic activity, and electrical conductivity [ [17] , [18] , [19] ]. PEDOT–AuNPs nanocomposites can be simply and rapidly obtained by the direct chemical reaction between chloroauric acid and the 3,4-ethylenedioxythiophene (EDOT) monomer [ 20 , 21 ].…”

Semiconducting Polymers for Neural Applications

“… 60 Additionally, PEDOT:PSS can also be used in drug-eluting studies, where a molecule that can suppress the foreign-body reaction is released, such as dexamethasone or derivatives thereof. 61 − 64 …”

“… 124 , 125 Additionally, PEDOT has been deposited in a variety of supporting matrices, 126 , 127 membrane materials such as Nafion, 128 carbon nanotubes, 127 and metal nanoparticles. 64 Crown ether functionalization for Na + and K + ion sensing has also been realized by this method. 129 , 130 Historically, the use of electrodeposition has been particularly important in the fabrication of implantable neural probe electrodes.…”