Carbon Nanotubes Grown on Metal Microelectrodes for the Detection of Dopamine

Cheng Yang, Christopher B. Jacobs, Michael D. Nguyen, Mallikarjunarao Ganesana, Alexander G. Zestos, Ilia N. Ivanov, Alexander A. Puretzky, Christopher M. Rouleau, David B. Geohegan, B. Jill Venton

Research output: Contribution to journalArticlepeer-review

114 Scopus citations

Abstract

Microelectrodes modified with carbon nanotubes (CNTs) are useful for the detection of neurotransmitters because the CNTs enhance sensitivity and have electrocatalytic effects. CNTs can be grown on carbon fiber microelectrodes (CFMEs) but the intrinsic electrochemical activity of carbon fibers makes evaluating the effect of CNT enhancement difficult. Metal wires are highly conductive and many metals have no intrinsic electrochemical activity for dopamine, so we investigated CNTs grown on metal wires as microelectrodes for neurotransmitter detection. In this work, we successfully grew CNTs on niobium substrates for the first time. Instead of planar metal surfaces, metal wires with a diameter of only 25 μm were used as CNT substrates; these have potential in tissue applications due to their minimal tissue damage and high spatial resolution. Scanning electron microscopy shows that aligned CNTs are grown on metal wires after chemical vapor deposition. By use of fast-scan cyclic voltammetry, CNT-coated niobium (CNT-Nb) microelectrodes exhibit higher sensitivity and lower ΔEp value compared to CNTs grown on carbon fibers or other metal wires. The limit of detection for dopamine at CNT-Nb microelectrodes is 11 ± 1 nM, which is approximately 2-fold lower than that of bare CFMEs. Adsorption processes were modeled with a Langmuir isotherm, and detection of other neurochemicals was also characterized, including ascorbic acid, 3,4-dihydroxyphenylacetic acid, serotonin, adenosine, and histamine. CNT-Nb microelectrodes were used to monitor stimulated dopamine release in anesthetized rats with high sensitivity. This study demonstrates that CNT-grown metal microelectrodes, especially CNTs grown on Nb microelectrodes, are useful for monitoring neurotransmitters.

Original languageEnglish
Pages (from-to)645-652
Number of pages8
JournalAnalytical Chemistry
Volume88
Issue number1
DOIs
StatePublished - Jan 5 2016

Funding

This research was supported by NIH Grant R21 DA037584. Synthesis and physical characterization of the CNT-metal wires were conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility (User Grant CNMS2014-083).

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