On-Chip Amperometric Measurement of Quantal Catecholamine Release Using Transparent Indium Tin Oxide Electrodes

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• 作者：Xiuhua Sun and Kevin D. Gillis
• 刊名：Analytical Chemistry
• 出版年：2006
• 出版时间：April 15, 2006
• 年：2006
• 卷：78
• 期：8
• 页码：2521 - 2525
• 全文大小：218K
• 年卷期：v.78,no.8(April 15, 2006)
• ISSN：1520-6882

文摘

Carbon-fiber amperometry has been extensively used tomonitor the time course of catecholamine release fromcells as individual secretory granules discharge theircontents during the process of quantal exocytosis, butmicrofabricated devices offer the promise of higherthroughput. Here we report development of a microchipdevice that uses transparent indium tin oxide (ITO)electrodes to measure quantal exocytosis from cells inmicrofluidic channels. ITO films on a glass substrate werepatterned as 20-m-wide stripes using photolithographyand wet etching and then coated with polylysine tofacilitate cell adherence. Microfluidic channels (100 mwide by 100 m deep) were formed by molding poly(dimethylsiloxane) (PDMS) on photoresist and then reversibly sealing the PDMS slab to the ITO-glass substrate. Bovine adrenal chromaffin cells were loaded intothe microfluidic channel and adhered to the ITO electrodes. Cells were stimulated to secrete by perfusing adepolarizing "high-K" solution while monitoring oxidationof catecholamines on the ITO electrode beneath the cellusing amperometry. Amperometric spikes with chargesranging from 0.1 to 1.5 pC were recorded with a signal-to-noise ratio comparable to that of carbon-fiber electrodes. Further development of this approach will enablehigh-throughput measurement of quantal catecholaminerelease simultaneously with optical cell measurementssuch as fluorescence.