Electro‐synthesized PEDOT/glutamate chemically modified electrode: a combination of electrical and biocompatible features

Abstract

BACKGROUND: Neural prosthetic devices have been developed that can facilitate the stimulation and recording of electrical activity when implanted in the central nervous system. The key parts of the devices are metal (gold) electrodes; however, surface modification of the gold electrode is desired. Conducting polymers are promising candidates for this purpose. RESULTS: A conducting polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT), was electro‐polymerized onto gold electrodes with a neural transmitter of glutamate (Glu) as dopant. A protocol of ion exchange was employed due to the difficulty of direct incorporation of Glu into PEDOT. Sodium p‐toluenesulfonate (TSNa) was chosen as the first dopant and subsequent incorporation of Glu was accomplished via ion exchange. The electrochemical properties of the resultant PEDOT/Glu were studied using electrochemical impedance spectroscopy and cyclic voltammetry. The purpose of incorporating Glu was to improve the biocompatibility of the coated electrode. The PEDOT/Glu‐coated electrode showed better cell attachment compared with a PEDOT/TSNa‐coated electrode in in vitro cell culture of PC12. The stability of PEDOT was studied by immersing the coated electrode in a biologically relevant reducing agent of glutathione. CONCLUSION: The charge capacity of the coated electrode had an initial slight decrease and then remained unchanged. Good electro‐activity was conserved, indicating the superior stability of PEDOT in the biological environment. Copyright © 2007 Society of Chemical Industry

New carbon nanotube–conducting polymer composite electrodes for drug delivery applications

“…This in turn makes such a CP‐DDS promising to be used in implantable systems and would allow drug release to be adjusted after administration of the DDS. Conjugated polymers such as polypyrrole (PPy) and poly(3,4‐ethylenedioxythiophene) (PEDOT) have been employed in the fabrication of CP‐DDSs10–12 and a wide spectrum of drug molecules has been investigated 8–13. However, there are several limitations that hamper the development of CP‐DDSs, including (1) that the drug molecules are generally incorporated in the bulk of the CP leading to low encapsulation; (2) that electrochemical deposition using a solution restricts homogeneous drug distribution throughout the whole surface of the CP; and (3) that rapid release of drug molecules associated with the limited surface area is encountered.…”

Partially sulfonated ethylene-vinyl alcohol copolymer as new substrate for 3,4-ethylenedioxythiophene vapor phase polymerization

“…These properties have opened new opportunities to prepare PEDOT‐based biomedical devices, including biosensors, neural probes, microelectrode arrays, and scaffolds for tissue engineering . In situ electrochemical and chemical polymerizations have been adopted to overcome the poor PEDOT processability while biocompatible doping agents, such as anionically modified polypeptides or glutamate, have been used to increase PEDOT conductivity properties …”

“…[11][12][13][14] In situ electrochemical and chemical polymerizations have been adopted to overcome the poor PEDOT processability while biocompatible doping agents, such as anionically modified polypeptides or glutamate, have been used to increase PEDOT conductivity properties. 15,16 To facilitate bioconjugation, PEDOT nanobiointerfaces have been obtained by electropolymerization of various functionalized EDOTs 17 or by incorporation of bioactive molecules during EDOT polymerization with a consequent possible decrease in electrical properties, adhesion to the electrode, or mechanical properties. 18 Alternatively, to prepare composite materials able to bind specific bioactive species for applications as bioelectronic devices, PEDOT has been vapor phase polymerized on poly (ethylene glycol) (PEG) or carboxylated PEG.…”

Conjugated polymers as robust carriers for controlled delivery of anti-inflammatory drugs

“…None of them, however, studied the stability of polymer matrix during stimulated drug release. This is an important question when considering medical applications of such matrices and their implementation into a human body [29][30][31][32].…”