Carbon-fiber microelectrodes (CFMEs) have been used for several years for the detection of neurotransmitters such as dopamine. Dopamine is a fundamentally important neurotransmitter and is also metabolized at a subsecond timescale. Recently, several metabolites of dopamine have been shown to be physiologically important such as 3-methoxytyramine (3-MT), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA). Many of these neurotransmitter metabolites are currently only detected with microdialysis coupled with liquid chromatography with relatively low temporal and spatial resolution. Current electrochemical methods such as the dopamine waveform (scanning from −0.4 to 1.3 V at 400 V s −1 ) are utilized to electrostatically repel anions such as DOPAC and promote dopamine adsorption to the surface of the electrode. Moreover, polymer coatings such as Nafion have been shown to electrostatically repel anions such as 5-hydroxyindoleacetic acid (5-HIAA). In this study, we develop novel polymer and waveform modifications for enhanced DOPAC detection. Applying the DOPAC waveform (scanning from 0 to 1.3 V at 400 V s −1 ) enhances DOPAC detection significantly because it does not include the negative holding potential of the dopamine waveform. Moreover, positively charged cationic polymers such as polyethyleneimine (PEI) allow for the preconcentration of DOPAC to the surface of the carbon fiber through an electrostatic attraction. The limit of detection for DOPAC for PEI coated CFMEs with the DOPAC waveform applied is 58.2 ± 2 nM as opposed to 291 ± 10 nM for unmodified electrodes applying the dopamine waveform ( n = 4). This work offers promise for the development of novel electrode materials and waveforms for the specific detection of several important biomolecules such as dopamine metabolite neurotransmitters.
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Polymer Modified Carbon Fiber Microelectrodes for Precision Neurotransmitter Metabolite Measurements
Carbon fiber-microelectrodes (CFMEs) are considered to be one of the standard electrodes for neurotransmitter detection such as dopamine (DA). DA is physiologically important for many pharmacological and behavioral states, but is readily metabolized on a fast, subsecond timescale. Recently, DA metabolites such as 3-methoxytyramine (3-MT) and 3,4-dihydroxyphenylacetaldehyde (DOPAL) were found to be involved in physiological functions, such as movement control and progressive neuro degeneration. However, there is no current assay to detect and differentiate them from DA. In this study, we demonstrate the co-detection of similarly structured neurochemicals such as DA, 3-MT, and DOPAL. We accomplished this through electrodepositing CFMEs with polyethyleneimine (PEI) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) polymers. This endowed the bare unmodified CFMEs with surface charge, physical, and chemical differences, which resulted in the improved sensitivity and selectivity of neurotransmitter detection. The differentiation and detection of 3-MT, DOPAL, and DA will potentially help further understand the important physiological roles that these dopaminergic metabolites play
- Award ID(s):
- 1936173
- NSF-PAR ID:
- 10203228
- Publisher / Repository:
- The Electrochemical Society
- Date Published:
- Journal Name:
- Journal of The Electrochemical Society
- Volume:
- 167
- Issue:
- 16
- ISSN:
- 0013-4651
- Page Range / eLocation ID:
- Article No. 167507
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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