title: Biocompatible PEDOT:Nafion composite electrode coatings for selective detection of neurotransmitters in vivo.
abstract: A Nafion and poly(3,4-ethylenedioxythiophene) (PEDOT) containing composite polymer has been electropolymerized on carbon-fiber microelectrodes with the goal of creating a mechanically stable, robust, and controllable electrode coating that increases the selectivity and sensitivity of in vivo electrochemical measurements. The coating is deposited on carbon-fiber microelectrodes by applying a triangle waveform from +1.5 V to -0.8 V and back in a dilute solution of ethylenedioxythiophene (EDOT) and Nafion in acetonitrile. Scanning electron microscopy demonstrated that the coating is uniform and ∼100 nm thick. Energy-dispersive X-ray spectroscopy demonstrated that both sulfur and fluorine are present in the coating, indicating the incorporation of PEDOT (poly(3,4-ethylenedioxythiophene) and Nafion. Two types of PEDOT:Nafion coated electrodes were then analyzed electrochemically. PEDOT:Nafion-coated electrodes made using 200 μM EDOT exhibit a 10-90 response time of 0.46 ± 0.09 s versus 0.45 ± 0.11 s for an uncoated fiber in response to a 1.0 μM bolus of dopamine. The electrodes coated using a higher EDOT concentration (400 μM) are slower with a 10-90 response time of 0.84 ± 0.19 s, but display increased sensitivity to dopamine, at 46 ± 13 nA/μM, compared to 26 ± 6 nA/μM for the electrodes coated in 200 μM EDOT and 13 ± 2 nA/μM for an uncoated fiber. PEDOT:Nafion-coated electrodes were lowered into the nucleus accumbens of a rat, and both spontaneous and electrically evoked dopamine release were measured. In addition to improvements in sensitivity and selectivity, the coating dramatically reduces acute in vivo biofouling.
authors.affiliation: 1306 East University Boulevard, Department of Chemistry and Biochemistry, University of Arizona , Tucson, Arizona 85721, United States.
authors.forename: Richard F
authors.initials: RF
authors.lastname: Vreeland
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Atcherley
authors.forename: Wilfred S
authors.initials: WS
authors.lastname: Russell
authors.forename: Jennifer Y
authors.initials: JY
authors.lastname: Xie
authors.forename: Dong
authors.initials: D
authors.lastname: Lu
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Laude
authors.forename: Frank
authors.initials: F
authors.lastname: Porreca
authors.forename: Michael L
authors.initials: ML
authors.lastname: Heien
mesh_terms: D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry; D000077482:Carbon Fiber; D004298:Dopamine / Q000032:analysis*; D017022:Flow Injection Analysis; D005465:Fluorocarbon Polymers / Q000737:chemistry*; D008297:Male; D008839:Microelectrodes; D008855:Microscopy, Electron, Scanning; D018377:Neurotransmitter Agents / Q000032:analysis*; D009714:Nucleus Accumbens / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry*; D017397:Prefrontal Cortex / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D000077482:Carbon Fiber; D005465:Fluorocarbon Polymers; D018377:Neurotransmitter Agents; D011108:Polymers; C121383:poly(3,4-ethylene dioxythiophene); C040402:perfluorosulfonic acid; D002244:Carbon; D004298:Dopamine