title: Magnetron sputtered diamond-like carbon microelectrodes for on-chip measurement of quantal catecholamine release from cells.
abstract: Carbon electrodes are widely used in electrochemistry due to their low cost, wide potential window, and low and stable background noise. Carbon-fiber electrodes (CFE) are commonly used to electrochemically measure "quantal" catecholamine release via exocytosis from individual cells, but it is difficult to integrate CFEs into lab-on-a-chip devices. Here we report the development of nitrogen doped diamond-like carbon (DLC:N) microelectrodes on a chip to monitor quantal release of catecholamines from cells. Advantages of DLC:N microelectrodes are that they are batch producible at low cost, and are harder and more durable than graphite films. The DLC:N microelectrodes were prepared by a magnetron sputtering process with nitrogen doping. The 30 microm by 40 microm DLC:N microelectrodes were patterned onto microscope glass slides by photolithography and lift-off technology. The properties of the DLC:N microelectrodes were characterized by AFM, Raman spectroscopy and cyclic voltammetry. Quantal catecholamine release was recorded amperometrically from bovine adrenal chromaffin cells on the DLC:N microelectrodes. Amperometric spikes due to quantal release of catecholamines were similar in amplitude and area as those recorded using CFEs and the background current and noise levels of microchip DLC:N electrodes were also comparable to CFEs. Therefore, DLC:N microelectrodes are suitable for microchip-based high-throughput measurement of quantal exocytosis with applications in basic research, drug discovery and cell-based biosensors.
authors.affiliation: Department of Electrical and Computer Engineering, University of Missouri-Columbia, 243 Engineering Bldg. West, Columbia, MO, 65211, USA.
authors.forename: Yuanfang
authors.initials: Y
authors.lastname: Gao
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Chen
authors.forename: Sanju
authors.initials: S
authors.lastname: Gupta
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Gillis
authors.forename: Shubhra
authors.initials: S
authors.lastname: Gangopadhyay
mesh_terms: D000311:Adrenal Glands / Q000166:cytology; D000818:Animals; D002244:Carbon / Q000737:chemistry; D000077482:Carbon Fiber; D002395:Catecholamines / Q000032:analysis* / Q000378:metabolism; D002417:Cattle; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism*; D018130:Diamond / Q000737:chemistry; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004563:Electrochemistry; D004867:Equipment Design; D005089:Exocytosis; D005898:Glass / Q000737:chemistry; D056656:Lab-On-A-Chip Devices; D008832:Microchemistry / Q000379:methods; D046208:Microchip Analytical Procedures / Q000379:methods*; D008839:Microelectrodes; D018625:Microscopy, Atomic Force; D018408:Patch-Clamp Techniques; D013059:Spectrum Analysis, Raman; D013379:Substrate Specificity
chemical_list: D000077482:Carbon Fiber; D002395:Catecholamines; D004129:Dimethylpolysiloxanes; C013830:baysilon; D002244:Carbon; D018130:Diamond