High Temporal Resolution Measurements of Dopamine with Carbon Nanotube Yarn Microelectrodes

详细信息    查看全文

• 作者：Christopher B. Jacobs ; Ilia N. Ivanov ; Michael D. Nguyen ; Alexander G. Zestos ; B. Jill Venton
• 刊名：Analytical Chemistry
• 出版年：2014
• 出版时间：June 17, 2014
• 年：2014
• 卷：86
• 期：12
• 页码：5721-5727
• 全文大小：317K
• 年卷期：v.86,no.12(June 17, 2014)
• ISSN：1520-6882

文摘

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 螖E_p than CFMEs, a limit of detection of 10 卤 0.8 nM, and a linear response to 25 渭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 CNTYMEs, 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.