title: Evaluation of carbon nanotube fiber microelectrodes for neurotransmitter detection: Correlation of electrochemical performance and surface properties.
abstract: Fibers made of CNTs are attractive microelectrode sensors because they can be directly fabricated into microelectrodes. Different protocols for making CNT fibers have been developed, but differences in surface structure and therefore electrochemical properties that result have not been studied. In this study, we correlated the surface and electrochemical properties for neurochemical detection at 3 types of materials: CNT fibers produced by wet spinning with (1) polyethylenimine (PEI/CNT) or (2) chlorosulfonic acid (CA/CNT), and (3) CNT yarns made by solid-based CNT drawing. CNT yarns had well-aligned, high purity CNTs, abundant oxygen functional groups, and moderate surface roughness which led to the highest dopamine current density (290 ± 65 pA/cm2) and fastest electron transfer kinetics. The crevices of the CNT yarn and PEI/CNT fiber microelectrodes allow dopamine to be momentarily trapped during fast-scan cyclic voltammetry detection, leading to thin-layer cell conditions and a response that was independent of applied waveform frequency. The larger crevices on the PEI/CNT fibers led to a slower time response, showing too much roughness is detrimental to fast detection. CA/CNT fibers have a smoother surface and lower currents, but their negative surface charge results in high selectivity for dopamine over uric acid or ascorbic acid. Overall, small crevices, high conductivity, and abundant oxygen groups led to high sensitivity for amine neurotransmitters, such as dopamine and serotonin. Thus, different surfaces of CNT fibers result in altered electrochemical properties and could be used in the future to predict and control electrochemical performance.
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, VA, 22904, United States.
authors.forename: Cheng
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, VA, 22904, United States.
authors.forename: Elefterios
authors.initials: E
authors.lastname: Trikantzopoulos
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831, United States.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Jacobs
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, VA, 22904, United States. Electronic address: jventon@virginia.edu.
authors.forename: B Jill
authors.initials: BJ
authors.lastname: Venton
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis / Q000737:chemistry; D015374:Biosensing Techniques; D004298:Dopamine / Q000032:analysis* / Q000737:chemistry; D004553:Electric Conductivity; D055664:Electrochemical Techniques; D004583:Electrons; D008839:Microelectrodes; D037742:Nanotubes, Carbon / Q000737:chemistry*; D018377:Neurotransmitter Agents / Q000032:analysis* / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D011094:Polyethyleneimine / Q000737:chemistry; D012701:Serotonin / Q000032:analysis* / Q000737:chemistry; D013451:Sulfonic Acids / Q000737:chemistry; D013499:Surface Properties; D014527:Uric Acid / Q000032:analysis / Q000737:chemistry
chemical_list: D037742:Nanotubes, Carbon; D018377:Neurotransmitter Agents; D013451:Sulfonic Acids; D014527:Uric Acid; C013880:chlorosulfonic acid; D012701:Serotonin; D011094:Polyethyleneimine; D001205:Ascorbic Acid; D010100:Oxygen; D004298:Dopamine
keywords: CNT fiber; Fast-scan cyclic voltammetry; Microelectrode; Neurotransmitter; Surface properties