Stability of poly(3,4‐ethylene dioxythiophene) materials intended for implants

Abstract

This study presents experiments designed to study the stability of the conducting polymer poly(3,4-ethylene dioxythiophene) (PEDOT), under simulated physiological conditions using phosphate-buffered saline (PBS) and hydrogen peroxide (H(2)O(2)) (0.01 M) at 37 degrees C over a 5- to 6-week period. Voltage pulsing in PBS was used as an additional test environment. The influence of switching the counter ion used in electropolymerization from polystyrene sulphonate (PSS) to heparin was investigated. Absorbance spectroscopy and cyclic voltammetry were used to evaluate the material properties. Most of the samples in H(2)O(2) lost both electroactivity and optical absorbance within the study period, but PEDOT:PSS was found slightly more stable than PEDOT:heparin. Polymers were relatively stable in PBS throughout the study period, with around 80% of electroactivity remaining after 5 weeks, disregarding delamination, which was a significant problem especially for polymer on indium tin oxide substrates. Voltage pulsing in PBS did not increase degradation. The counter ion influenced the time course of degradation in oxidizing agents.

Poly(3,4‐ethylenedioxythiophene):GlycosAminoGlycan Aqueous Dispersions: Toward Electrically Conductive Bioactive Materials for Neural Interfaces

“…[15][16][17] A variety of negatively charged biomolecules have been studied as dopants, such as alginate, dextran sulfate, chondroitin sulfate, [18][19][20] heparin, and hyaluronic acid. [11,21,22] In most of these reports, the conducting polymer/biomolecule complexes were prepared electrochemically limiting their scalability due to the low area of the electrode where the polymer is usually deposited. [23] Only recently, Wallace and co-workers [24] have reported the synthesis of PEDOT:dextran sulfate aqueous dispersions, which allow the production of high amounts of conductive materials and the coatings of large areas by casting using dextran sulfate dopant.…”

Electronic Control of Cell Detachment Using a Self‐Doped Conducting Polymer

“…One of the most stable conjugated polymers is PEDOT, which has been used in various applications. [17] The synthesis of conjugated polymers that enable easy processing in aqueous media has been one of the major challenges in this field. [18,19] Recently we reported a successful synthetic route to a fully water-soluble form of PEDOT-S. [20] This polymer showed a substantial degree of self-doping and conductivity above 12 S cm -1 .…”

“…Upon electrochemical oxidation the self-doping process is accompanied by an expulsion of charge balancing protons to the surrounding electrolyte, and charge neutralization leads to the inclusion of cations. [17] When oxidizing the polymer beyond its pristine state (20-30% doping level), [18] more anions are needed to compensate for the additional positive charges on the polymer backbone. These anions can be supplied from either the covalently attached sulfonate groups on PEDOT-S:H (more self-doping), or from inclusion of the surrounding electrolyte.…”

Nanostructured Coatings for Improved Charge Delivery to Neurons

“…Polypyrrole has seen frequent use due to its ease of growth and low toxicity [188,189]. PEDOT, despite possessing a monomer with lower but still acceptable aqueous solubility, exhibits greatly improved chemical and electrochemical stability over polypyrrole [183][184][185]190]. Due to these advantages, PEDOT has been the subject of much recent development.…”