Carbon Nanotube-Based Microelectrodes for Enhanced Neurochemical Detection.

Carbon nanotube (CNT) fiber microelectrodes have been developed as electrode materials for the detection of neurotransmitters using fast scan cyclic voltammetry (FSCV). We have used acid-wet spinning to create "neat" carbon nanotube fibers and utilized them as electrode materials. Thirty-forty micron diameter acid spun CNT fiber microelectrodes were more sensitive than PEI-CNT fiber microelectrodes, with a 3 nM limit of detection. They also had faster electron transfer kinetics and a greater reversibility for the oxidation of dopamine using FSCV than CFMEs and other carbon nanomaterials. The acid spun CNT fiber microelectrodes also displayed a frequency independent response for the peak oxidation current of dopamine. This property was also seen in other CNT materials such as PEI-CNT fiber microelectrodes and CNT-Yarn microelectrodes. Upon varying the frequency from 10 Hz to 100 Hz, there was no decrease in sensitivity. When scanning at 2,000 V/s, there was no decrease in sensitivity upon changing the frequency from 10 Hz to 500 Hz. This could potentially allow for a 2 ms sampling rate for FSCV, comparable to those used with amperometry as opposed to 100 ms temporal resolution of traditional FSCV, an almost two orders of magnitude difference. Since the frequency independent response is seen with many CNT fibers/yarns, it suggests it is a fundamental property of the CNTs shared by many types of CNT fibers and yarns.