期刊
ANALYTICAL CHEMISTRY
卷 86, 期 12, 页码 5721-5727出版社
AMER CHEMICAL SOC
DOI: 10.1021/ac404050t
关键词
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资金
- Center for Nanophase Materials Sciences [CNMS2012-070, CNMS2014-083]
- Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy
- National Science Foundation (NSF) [CHE0645587522]
- NIH [R21DA037584, R01MH085159]
Fast-scan cyclic voltammetry (FSCV) can detect small changes in dopamine concentration; however, measurements are typically limited to scan repetition frequencies of 10 Hz. Dopamine oxidation at carbon-fiber microelectrodes (CFMEs) is dependent on dopamine adsorption, and increasing the frequency of FSCV scan repetitions decreases the oxidation current, because the time for adsorption is decreased. Using a commercially available carbon nanotube yarn, we characterized carbon nanotube yarn microelectrodes (CNTYMEs) for high-speed measurements with FSCV. For dopamine, CNTYMEs have a significantly lower Delta E-p than CFMEs, a limit of detection of 10 +/- 0.8 nM, and a linear response to 25 mu M. Unlike CFMEs, the oxidation current of dopamine at CNTYMEs is independent of scan repetition frequency. At a scan rate of 2000 V/s, dopamine can be detected, without any loss in sensitivity, with scan frequencies up to 500 Hz, resulting in a temporal response that is four times faster than CFMEs. While the oxidation current is adsorption-controlled at both CFMEs and CNTYIVLEs, the adsorption and desorption kinetics differ. The desorption coefficient of dopamine-o-quinone (DOQ), the oxidation product of dopamine, is an order of magnitude larger than that of dopamine at CFMEs; thus, DOQ desorbs from the electrode and can diffuse away. At CNTYMEs, the rates of desorption for dopamine and dopamine-o-quinone are about equal, resulting in current that is independent of scan repetition frequency. Thus, there is no compromise with CNTYMEs: high sensitivity, high sampling frequency, and high temporal resolution can be achieved simultaneously. Therefore, CNTYMEs are attractive for high-speed applications.
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