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Spatially and Temporally Resolved Single-Cell Exocytosis Utilizing Individually Addressable Carbon Microelectrode Arrays

Supporting Info

Bo Zhang,^† Kelly L. Adams,^†^‡ Sarah J. Luber,^† Daniel J. Eves,^† Michael L. Heien,^† and Andrew G. Ewing*^†^‡

Department of Chemistry, 104 Chemistry Research Building, The Pennsylvania State University, University Park, Pennsylvania 16802, and Department of Chemistry, Gteborg University, Kemivgen 10, SE-41296, Gteborg, Sweden

Anal. Chem., 2008, 80 (5), pp 1394–1400

DOI: 10.1021/ac702409s

Publication Date (Web): January 31, 2008

†

The Pennsylvania State University.

‡

Göteborg University.

To whom correspondence should be addressed. E-mail: andrew.ewing@ chem.gu.se.

Abstract

We report the fabrication and characterization of carbon microelectrode arrays (MEAs) and their application to spatially and temporally resolve neurotransmitter release from single pheochromocytoma (PC12) cells. The carbon MEAs are composed of individually addressable 2.5-μm-radius microdisks embedded in glass. The fabrication involves pulling a multibarrel glass capillary containing a single carbon fiber in each barrel into a sharp tip, followed by beveling the electrode tip to form an array (10−20 μm) of carbon microdisks. This simple fabrication procedure eliminates the need for complicated wiring of the independent electrodes, thus allowing preparation of high-density individually addressable microelectrodes. The carbon MEAs have been characterized using scanning electron microscopy, steady-state and fast-scan voltammetry, and numerical simulations. Amperometric results show that subcellular heterogeneity in single-cell exocytosis can be electrochemically detected with MEAs. These ultrasmall electrochemical probes are suitable for detecting fast chemical events in tight spaces, as well as for developing multifunctional electrochemical microsensors.

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