title: Carbon Nanotubes Grown on Metal Microelectrodes for the Detection of Dopamine.
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.
authors.affiliation: Department of Chemistry, University of Virginia , McCormick Road, Box 400319, Charlottesville, Virginia 22904-4319, United States.
authors.forename: Cheng
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Chemistry, University of Virginia , McCormick Road, Box 400319, Charlottesville, Virginia 22904-4319, United States.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Jacobs
authors.affiliation: Department of Chemistry, University of Virginia , McCormick Road, Box 400319, Charlottesville, Virginia 22904-4319, United States.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry, University of Virginia , McCormick Road, Box 400319, Charlottesville, Virginia 22904-4319, United States.
authors.forename: Mallikarjunarao
authors.initials: M
authors.lastname: Ganesana
authors.affiliation: Department of Chemistry, University of Virginia , McCormick Road, Box 400319, Charlottesville, Virginia 22904-4319, United States.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Zestos
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , 1 Bethel Valley Road, Building 8610, Oak Ridge, Tennessee 37831, United States.
authors.forename: Ilia N
authors.initials: IN
authors.lastname: Ivanov
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , 1 Bethel Valley Road, Building 8610, Oak Ridge, Tennessee 37831, United States.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Puretzky
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , 1 Bethel Valley Road, Building 8610, Oak Ridge, Tennessee 37831, United States.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Rouleau
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , 1 Bethel Valley Road, Building 8610, Oak Ridge, Tennessee 37831, United States.
authors.forename: David B
authors.initials: DB
authors.lastname: Geohegan
authors.affiliation: Department of Chemistry, University of Virginia , McCormick Road, Box 400319, Charlottesville, Virginia 22904-4319, United States.
authors.forename: B Jill
authors.initials: BJ
authors.lastname: Venton
mesh_terms: D004298:Dopamine / Q000032:analysis*; D055664:Electrochemical Techniques; D008839:Microelectrodes; D037742:Nanotubes, Carbon / Q000737:chemistry*; D018377:Neurotransmitter Agents / Q000032:analysis*; D009556:Niobium / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D037742:Nanotubes, Carbon; D018377:Neurotransmitter Agents; D009556:Niobium; D004298:Dopamine