Electro-synthesized PEDOT/glutamate chemically modified electrode: a combination of electrical and bicomptible features

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 PEDOTIGlu were studied using electrochemical impedance spectroscopy and cyclic voltarnmetry. 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 PEDOTITSNa-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. (c) 2007 Society of Chemical Industry