Carbon Fiber Microelectrodes ● Sensitive, renewable/durable and economical carbon fiber electrodes for electrochemical detection of oxidizable compounds Carbon fiber microelectrodes have been used in both the detection of oxidizable compounds (Gonon, et al., 1978; Cahill and Wightman, 1995) and extracellular single-unit recording (Armstrong-James and Millar, 1979). WPI’s ultra-sensitive and low-noise carbon fiber (CF) electrodes can be applied, with our Micro-C Potentiostat or similar instruments, in the electrochemical detection of catecholamines (epinephrine, norepinephrine and dopamine), indolamines (serotonin, 5-HT or melatonin), ascorbic acid, Fe (II), and other oxidizable compounds. CF electrodes (diameter of 10 or 30 µm) respond with an excellent linearity to the oxidizable compounds (Fig. 1) and can detect the compounds as low as 0.2 nM. While the shorter (25-100 µm) CF electrodes are suitable for in vivo amperometric and voltammetric measurements, the longer CF electrodes provide higher sensitivity and are especially useful for the in vitro studies (amperometric or differential pulse voltammetry). When used with the Micro-C Potentiostat, these CF electrodes can be activated and renewed in sensitivity for multiple use. The selective detection of catecholamines can be achieved with our Nafion-coated CF electrodes. For selective detection of 5-HT and ascorbic acid, please contact WPI for more information. 50 Potential (V) 0 -50 -100 0 5 10 Time (ms) Fig. 2 — Extracellular recording using a carbon electrode in CA1 region of the hippocampus in an anesthetized rat shows ultralow noise (-<5 µV-). Courtesy: Dr. Carolyn Harley of Memorial University, Newfoundland, Canada. BIOSENSING References P. S. Cahill, R. M. Whightman, Anal. Chem., 67, 2599-2605 (1995). F. Gonon, et al., Hebd Seances Acad. Sci. Ser. 286, 1203 (1978). M. Armstrong-James, J. Millar, J. Neurosci. Methods, 1, 279 (1979). CARBON FIBER MICROELECTRODES, UNCOATED Diameter Length CF10-100 10 µm 100 µm CF10-250 10 µm 250 µm CF10-500 * 10 µm 500 µm CF30-50 * 30 µm 50 µm CF30-100 30 µm 100 µm CF30-500 * 30 µm 500 µm CF30-1000 * 30 µm 1000 µm Dopamine Concentration/Response Curve 1000000 100000 (pack of 5) Current Output (pA) 10000 1000 100 10 1 0.1 1 10 100 1000 10000 100000 1000000 Concentration (ng/ml) Fig. 1 — Excellent linearity in the response of carbon fiber electrode (CF30-500) to dopamine recorded on Micro-C. Courtesy: Drs. D. Yeomans and X.-T. Wang, University of Illinois at Chicago. CARBON FIBER MICROELECTRODES, NAFION-COATED Diameter Length (pack of 5) CFN10-50 * 10 µm 50 µm CFN10-100 * 10 µm 100 µm CFN10-250 * 10 µm 250 µm CFN30-50 * 30 µm 50 µm CFN30-100 * 30 µm 100 µm CFN30-250 * 30 µm 250 µm CFN30-500 * 30 µm 500 µm CFN30-1000 * 30 µm 1000 µm * Built to order — allow up to 4 weeks manufacturing time. 1.5 mm O.D. glass pipette Gold-plated connector pin 0.031 in. (0.79 mm) glass insulation 30 µ or 10 µ carbon fiber Carbon fiber microelectrodes, approximately 25-50 mm (1-2 in. ) long, feature a gold-plated pin for connection to the probe. cement 25-1000 mm UK: Tel: +44 (0)1462 424700 • wpiuk@wpi-europe.com World Precision Instruments www.wpiinc.com Germany: Tel: +49 (0)30-6188845 • wpide@wpi-europe.com US: Tel: 941-371-1003 • sales@wpiinc.com 59