This work demonstrates that the use of the waveforms with extended anodic potentials for FSCV (up to 1.3 V and 1.4 V vs Ag/AgCl) at carbon electrodes causes oxidative etching of the surface, a process that is not detectable with similar scans to 1.0 V. PPF microelectrodes were used to establish the effect with the aid of surface analysis techniques (XPS and AFM). Both XPS and AFM tracking of surface integrity showed etching of the carbon electrode following the application of these waveforms. Exposure of PPF microelectrodes to the extended waveforms for long periods of time (up to 10 hours) led to complete etching of the electrodes, confirmed with optical microscopy. Oxidative etching was shown to occur on carbon-fiber microelectrodes with complete removal observed after 65 hours (for the 1.3 V waveform) or 6 hours (for the 1.4 V waveform). We postulate that the etching occurs as a consequence of evolution of carbon dioxide or exfoliation of graphite oxide and/or carbon particles take place. Oxidative etching of the carbon electrodes with the extended waveforms provides a number of benefits in electroanalytical detection.
The important result of oxidative etching is the continuous regeneration of a fresh carbon surface. The ability to renew electrode surfaces helps to prevent electrode fouling. The demonstrated effect maybe the reason why carbon-fiber microelectrodes remain active in vivo which makes a carbon microelectrode a useful analytical tool for the in vivo detection of catecholamines since the state of the surface can be restored by a simple electrochemical procedure. In addition, microelectrodes with a renewable surface open new horizons for the use of waveforms with extended anodic potential limits for the electrochemical detection in chemically complex environments since this continual surface regeneration prevents electrode fouling and maintenance of electrode sensitivity.
REFERENCES
1. McCreery, R. L., Carbon electrodes: structural effects on electron transfer kinetics. Marcel-Dekker: New York, 1991; Vol. 17, p 221-373.
2. Kissinger, P. T.; Heineman, W. R., Laboratory Techniques in Electroanalytical Chemistry. Marcel Dekker Inc: 1996.
3. Pandolfo, A. G.; Hollenkamp, A. F., Carbon properties and their role in supercapacitors. Journal of Power Sources 2006, 157, (1), 11-27.
4. McCreery, R. L., Advanced carbon electrode materials for molecular electrochemistry. Chemical Reviews 2008, 108, (7), 2646-2687.
5. Balasubramanian, K.; Burghard, M., Biosensors based on carbon nanotubes. Analytical and Bioanalytical Chemistry 2006, 385, (3), 452-468.
6. Avouris, P.; Chen, Z. H.; Perebeinos, V., Carbon-based electronics. Nature Nanotechnology 2007, 2, (10), 605-615.
7. Robinson, D. L.; Hermans, A.; Seipel, A. T.; Wightman, R. M., Monitoring rapid chemical communication in the brain. Chemical Reviews 2008, 108, (7), 2554- 2584.
8. Kita, J. M.; Wightman, R. M., Microelectrodes for studying neurobiology. Current Opinion in Chemical Biology 2008, 12, (5), 491-496.
9. Owesson-White, C. A.; Cheer, J. F.; Beyene, M.; Carelli, R. M.; Wightman, R. M., Dynamic changes in accumbens dopamine correlate with learning during intracranial self-stimulation. Proceedings of the National Academy of Sciences of the United States of America 2008, 105, (33), 11957-11962.
10. Roitman, M. F.; Wheeler, R. A.; Wightman, R. M.; Carelli, R. M., Real-time chemical responses in the nucleus accumbens differentiate rewarding and aversive stimuli. Nature Neuroscience 2008, 11, (12), 1376-1377.
11. Zachek, M. K.; Hermans, A.; Wightman, R. M.; McCarty, G. S., Electrochemical dopamine detection: Comparing gold and carbon fiber microelectrodes using background subtracted fast scan cyclic voltammetry. Journal of Electroanalytical Chemistry 2008, 614, (1-2), 113-120.
12. Fagan, D. T.; Hu, I. F.; Kuwana, T., Vacuum Heat-Treatment for Activation of Glassy-Carbon Electrodes. Analytical Chemistry 1985, 57, (14), 2759-2763. 13. Poon, M.; Mccreery, R. L., Insitu Laser Activation of Glassy-Carbon Electrodes.
Analytical Chemistry 1986, 58, (13), 2745-2750.
14. Strand, A. M.; Venton, B. J., Flame etching enhances the sensitivity of carbon- fiber microelectrodes. Analytical Chemistry 2008, 80, (10), 3708-3715.
15. Chen, P. H.; McCreery, R. L., Control of electron transfer kinetics at glassy carbon electrodes by specific surface modification. Analytical Chemistry 1996, 68, (22), 3958-3965.
16. Baur, J. E.; Kristensen, E. W.; May, L. J.; Wiedemann, D. J.; Wightman, R. M., Fast-Scan Voltammetry of Biogenic Amines. Analytical Chemistry 1988, 60, (13), 1268-1272.
17. Bath, B. D.; Michael, D. J.; Trafton, B. J.; Joseph, J. D.; Runnels, P. L.; Wightman, R. M., Subsecond adsorption and desorption of dopamine at carbon- fiber microelectrodes. Analytical Chemistry 2000, 72, (24), 5994-6002.
18. Gotch, A. J.; Kelly, R. S.; Kuwana, T., Characterization and modeling of the nonfaradaic response of ultrahigh surface area carbon fibers by electrochemical flow injection analysis. Journal of Physical Chemistry B 2003, 107, (4), 935-941. 19. Xie, Y. M.; Sherwood, P. M. A., X-Ray Photoelectron Spectroscopic Studies of
Carbon-Fiber Surfaces .11. Differences in the Surface-Chemistry and Bulk Structure of Different Carbon-Fibers Based on Poly(Acrylonitrile) and Pitch and Comparison with Various Graphite Samples. Chemistry of Materials 1990, 2, (3), 293-299.
20. Gonon, F.; Buda, M.; Cespuglio, R.; Jouvet, M.; Pujol, J. F., Invivo Electrochemical Detection of Catechols in the Neostriatum of Anesthetized Rats - Dopamine or Dopac. Nature 1980, 286, (5776), 902-904.
21. Gonon, F. G.; Fombarlet, C. M.; Buda, M. J.; Pujol, J. F., Electrochemical Treatment of Pyrolytic Carbon-Fiber Electrodes. Analytical Chemistry 1981, 53, (9), 1386-1389.
22. Kovach, P. M.; Ewing, A. G.; Wilson, R. L.; Wightman, R. M., Invitro Comparison of the Selectivity of Electrodes for Invivo Electrochemistry. Journal of Neuroscience Methods 1984, 10, (3), 215-227.
23. Hafizi, S.; Kruk, Z. L.; Stamford, J. A., Fast Cyclic Voltammetry - Improved Sensitivity to Dopamine with Extended Oxidation Scan Limits. Journal of Neuroscience Methods 1990, 33, (1), 41-49.
24. Heien, M. L. A. V.; Phillips, P. E. M.; Stuber, G. D.; Seipel, A. T.; Wightman, R. M., Overoxidation of carbon-fiber microelectrodes enhances dopamine adsorption and increases sensitivity. Analyst 2003, 128, (12), 1413-1419.
25. Kim, J.; Song, X.; Kinoshita, K.; Madou, M.; White, B., Electrochemical studies of carbon films from pyrolyzed photoresist. Journal of the Electrochemical Society 1998, 145, (7), 2314-2319.
26. Ranganathan, S.; McCreery, R.; Majji, S. M.; Madou, M., Photoresist-derived carbon for microelectromechanical systems and electrochemical applications. Journal of the Electrochemical Society 2000, 147, (1), 277-282.
27. Ranganathan, S.; McCreery, R. L., Electroanalytical performance of carbon films with near-atomic flatness. Analytical Chemistry 2001, 73, (5), 893-900.
28. Zachek, M. K.; Takmakov, P.; Moody, B.; Wightman, R. M.; McCarty, G. S., Simultaneous Decoupled Detection of Dopamine and Oxygen Using Pyrolyzed Carbon Microarrays and Fast-Scan Cyclic Voltammetry. Analytical Chemistry 2009, 81, (15), 6258-6265.
29. Cahill, P. S.; Walker, Q. D.; Finnegan, J. M.; Mickelson, G. E.; Travis, E. R.; Wightman, R. M., Microelectrodes for the measurement of catecholamines in biological systems. Analytical Chemistry 1996, 68, (18), 3180-3186.
30. Deakin, M. R.; Wightman, R. M., The Kinetics of Some Substituted Catechol/Ortho-Quinone Couples at a Carbon Paste Electrode. Journal of Electroanalytical Chemistry 1986, 206, (1-2), 167-177.
31. Gerhardt, G.; Adams, R. N., Determination of Diffusion-Coefficients by Flow- Injection Analysis. Analytical Chemistry 1982, 54, (14), 2618-2620.
32. Kristensen, E. W.; Wilson, R. L.; Wightman, R. M., Dispersion in Flow-Injection Analysis Measured with Microvoltammetric Electrodes. Analytical Chemistry 1986, 58, (4), 986-988.
33. Bard, A. J.; Faulkner, L. R., Electrochemical Methods. Wiley New York: 2001. 34. Kawagoe, K. T.; Garris, P. A.; Wightman, R. M., Ph-Dependent Processes at
Nafion(R)-Coated Carbon-Fiber Microelectrodes. Journal of Electroanalytical Chemistry 1993, 359, (1-2), 193-207.
35. Runnels, P. L.; Joseph, J. D.; Logman, M. J.; Wightman, R. M., Effect of pH and surface functionalities on the cyclic voltammetric responses of carbon-fiber microelectrodes. Analytical Chemistry 1999, 71, (14), 2782-2789.
36. Hermans, A. Fabrication and applications of dopamine-sensitive electrodes. Ph. D. Thesis, University of North Carolina at Chapel Hill, 2007.
37. Yue, Z. R.; Jiang, W.; Wang, L.; Gardner, S. D.; Pittman, C. U., Surface characterization of electrochemically oxidized carbon fibers. Carbon 1999, 37, (11), 1785-1796.
38. Goss, C. A.; Brumfield, J. C.; Irene, E. A.; Murray, R. W., Imaging the Incipient Electrochemical Oxidation of Highly Oriented Pyrolytic-Graphite. Analytical Chemistry 1993, 65, (10), 1378-1389.
39. Zhou, J. G.; Booker, C.; Li, R. Y.; Zhou, X. T.; Sham, T. K.; Sun, X. L.; Ding, Z. F., An electrochemical avenue to blue luminescent nanocrystals from multiwalled carbon nanotubes (MWCNTs). Journal of the American Chemical Society 2007, 129, (4), 744-745.
40. Lu, J.; Yang, J. X.; Wang, J. Z.; Lim, A. L.; Wang, S.; Loh, K. P., One-Pot Synthesis of Fluorescent Carbon Nanoribbons, Nanoparticles, and Graphene by the Exfoliation of Graphite in Ionic Liquids. ACS Nano 2009, 3, (8), 2367-2375. 41. Zheng, L. Y.; Chi, Y. W.; Dong, Y. Q.; Lin, J. P.; Wang, B. B.,
Electrochemiluminescence of Water-Soluble Carbon Nanocrystals Released Electrochemically from Graphite. Journal of the American Chemical Society 2009, 131, (13), 4564-+.
42. Lee, C. M.; Pai, Y. H.; Shieu, F. S., Ultrahydrophobic and Microporous Electrodes Fabricated by Fluorocarbon Plasma Etching of Carbon Fiber. Journal of the Electrochemical Society 2009, 156, (8), B923-B926.
43. Soriaga, M. P.; Hubbard, A. T., Determination of the Orientation of Adsorbed Molecules at Solid-Liquid Interfaces by Thin-Layer Electrochemistry - Aromatic- Compounds at Platinum-Electrodes. Journal of the American Chemical Society 1982, 104, (10), 2735-2742.
44. Ssenyange, S.; Du, R.; Mcdermott, M. T., Fabrication of arrays of carbon micro- and nanostructures via electrochemical etching. Micro & Nano Letters 2009, 4, (1), 22-26.
45. Kiema, G. K.; Aktay, M.; McDermott, M. T., Preparation of reproducible glassy carbon electrodes by removal of polishing impurities. Journal of Electroanalytical Chemistry 2003, 540, 7-15.
46. Hermans, A.; Seipel, A. T.; Miller, C. E.; Wightman, R. M., Carbon-fiber microelectrodes modified with 4-sulfobenzene have increased sensitivity and selectivity for catecholamines. Langmuir 2006, 22, (5), 1964-1969.
47. Kolbe, H., Zersetzung der Valeriansäure durch den elektrischen Strom. Annalen der Chemie und Pharmacie 1849, 64 (3), 339–341.
48. Lund, H.; Hammerich, O., Organic Electrochemistry. 4th ed.; M. Dekker: New York, 2001; p vii, 1393 p.
49. Tenreiro, A. M.; Nabais, C.; Correia, J. P.; Fernandes, F. M. S. S.; Romero, J. R.; Abrantes, L. M., Progress in the understanding of tyramine electropolymerisation mechanism. Journal of Solid State Electrochemistry 2007, 11, (8), 1059-1069. 50. de Castro, C. M.; Vieira, S. N.; Goncalves, R. A.; Brito-Madurro, A. G.; Madurro,
J. M., Electrochemical and morphologic studies of nickel incorporation on graphite electrodes modified with polytyramine. Journal of Materials Science 2008, 43, (2), 475-482.
51. Cooper, S. E.; Venton, B. J., Fast-scan cyclic voltammetry for the detection of tyramine and octopamine. Analytical and Bioanalytical Chemistry 2009, 394, (1), 329-336.
52. Pihel, K.; Hsieh, S.; Jorgenson, J. W.; Wightman, R. M., Electrochemical Detection of Histamine and 5-Hydroxytryptamine at Isolated Mast-Cells. Analytical Chemistry 1995, 67, (24), 4514-4521.
Chapter 3
Characterization of Local pH Changes in Brain Using Fast-Scan Cyclic Voltammetry with Carbon Microelectrodes.