title: Fully automated microchip system for the detection of quantal exocytosis from single and small ensembles of cells.
abstract: A lab-on-a-chip device that enables positioning of single or small ensembles of cells on an aperture in close proximity to a mercaptopropionic acid (MPA) modified sensing electrode has been developed and characterized. The microchip was used for the detection of Ca(2+)-dependent quantal catecholamine exocytosis from single as well as small assemblies of rat pheochromocytoma (PC12) cells. The frequency of events increased considerably upon depolarization of the PC12 cell membrane using a high extracelluar concentration of potassium. The number of recorded events could be correlated with the number of cells immobilized on the electrode. Quantal characteristics, such as the number of released molecules per recorded event, are equivalent to data obtained using conventional carbon fiber microelectrodes. The detection sensitivity of the device allows for the detection of less than 10 000 dopamine molecules in a quantal release. The distribution of peak rise-time and full width at half maximum was constant during measurement periods of several minutes demonstrating the stability of the MPA modified surface.
authors.affiliation: Department of Analytical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Christer
authors.initials: C
authors.lastname: Spégel
authors.forename: Arto
authors.initials: A
authors.lastname: Heiskanen
authors.forename: Simon
authors.initials: S
authors.lastname: Pedersen
authors.forename: Jenny
authors.initials: J
authors.lastname: Emnéus
authors.forename: Tautgirdas
authors.initials: T
authors.lastname: Ruzgas
authors.forename: Rafael
authors.initials: R
authors.lastname: Taboryski
mesh_terms: D015097:3-Mercaptopropionic Acid / Q000737:chemistry; D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002395:Catecholamines / Q000032:analysis* / Q000378:metabolism; D018914:Cells, Immobilized; D004298:Dopamine / Q000032:analysis / Q000378:metabolism; D004563:Electrochemistry; D005089:Exocytosis / Q000502:physiology; D046228:Microarray Analysis / Q000295:instrumentation / Q000379:methods*; D008839:Microelectrodes; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D016716:PC12 Cells; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000737:chemistry; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013499:Surface Properties; D013997:Time Factors
chemical_list: D002395:Catecholamines; D015097:3-Mercaptopropionic Acid; D011188:Potassium; D002118:Calcium; D004298:Dopamine