title: Doped overoxidized polypyrrole microelectrodes as sensors for the detection of dopamine released from cell populations.
abstract: A surface modification of interdigitated gold microelectrodes (IDEs) with a doped polypyrrole (PPy) film for detection of dopamine released from populations of differentiated PC12 cells is presented. A thin PPy layer was potentiostatically electropolymerized from an aqueous pyrrole solution onto electrode surfaces. The conducting polymer film was doped during electropolymerization by introducing counter-ions in the monomer solution. Several counter-ions were tested and the resulting electrode modifications were characterized electrochemically to find the optimal dopant that increases sensitivity in dopamine detection. Overoxidation of the PPy films was shown to contribute to a significant enhancement in sensitivity to dopamine. The changes caused by overoxidation in the electrochemical behavior and electrode morphology were investigated using cyclic voltammetry and SEM as well as AFM, respectively. The optimal dopant for dopamine detection was found to be polystyrene sulfonate anion (PSS(-)). Rat pheochromocytoma (PC12) cells, a suitable model to study exocytotic dopamine release, were differentiated on IDEs functionalized with an overoxidized PSS(-)-doped PPy film. The modified electrodes were used to amperometrically detect dopamine released by populations of cells upon triggering cellular exocytosis with an elevated K(+) concentration. A comparison between the generated current on bare gold electrodes and gold electrodes modified with overoxidized doped PPy illustrates the clear advantage of the modification, yielding 2.6-fold signal amplification. The results also illustrate how to use cell population based dopamine exocytosis measurements to obtain biologically significant information that can be relevant in, for instance, the study of neural stem cell differentiation into dopaminergic neurons.
authors: Department of Micro- and Nanotechnology, Technical University of Denmark, Ørsted Plads 345E, 2800 Kgs. Lyngby, Denmark.
authors: Luigi
authors: L
authors: Sasso
authors: Arto
authors: A
authors: Heiskanen
authors: Francesco
authors: F
authors: Diazzi
authors: Maria
authors: M
authors: Dimaki
authors: Jaime
authors: J
authors: Castillo-León
authors: Marco
authors: M
authors: Vergani
authors: Ettore
authors: E
authors: Landini
authors: Roberto
authors: R
authors: Raiteri
authors: Giorgio
authors: G
authors: Ferrari
authors: Marco
authors: M
authors: Carminati
authors: Marco
authors: M
authors: Sampietro
authors: Winnie E
authors: WE
authors: Svendsen
authors: Jenny
authors: J
authors: Emnéus
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation*; D004298:Dopamine / Q000032:analysis* / Q000378:metabolism*; D004563:Electrochemistry; D005089:Exocytosis; D006046:Gold / Q000737:chemistry; D008839:Microelectrodes; D010084:Oxidation-Reduction; D016716:PC12 Cells; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D051381:Rats
chemical_list: D011108:Polymers; D011758:Pyrroles; C067635:polypyrrole; D006046:Gold; D004298:Dopamine