Overoxidation of carbon-fiber microelectrodes enhances dopamine adsorption and increases sensitivityElectronic supplementary information (ESI) available: National Instruments Data Acquisition System. See http://www.rsc.org/suppdata/an/b3/b307024g/

Abstract

The voltammetric responses of carbon-fiber microelectrodes with a 1.0 V and a 1.4 V anodic limit were compared in this study. Fast-scan cyclic voltammetry was used to characterize the response to dopamine and several other neurochemicals. An increase in the adsorption properties of the carbon fiber leads to an increase in sensitivity of 9 fold in vivo. However the temporal response of the sensor is slower with the more positive anodic limit. Increased electron transfer kinetics also causes a decrease in the relative sensitivity for dopamine vs. other neurochemicals, and a change in their cyclic voltammograms. Stimulated release in the caudate-putamen was pharmacologically characterized in vivo using Ro-04-1284 and pargyline, and was consistent with that expected for dopamine.

Real-time measurement of dopamine fluctuations after cocaine in the brain of behaving rats

“…metric signal was collected by using LABVIEW (National Instruments, Austin, TX) and a multifunction data-acquisition board (PCI-6052E, National Instruments). A PCI-6711E (National Instruments) board was used to synchronize waveform acquisition, data collection, and stimulation delivery (7). Waveform processing and current transduction used custom-built instrumentation (University of North Carolina, Department of Chemistry, Electronics Facility).…”

“…Fast-scan cyclic voltammetry at carbonfiber microelectrodes (6) provides rapid measurements and yields a chemical signature, the cyclic voltammogram, that allows distinction among electroactive molecules that are present in the brain. The electrode is highly sensitive to dopamine relative to dihydroxyphenylacetic acid and ascorbate, two major interferants, and the voltammogram of dopamine is distinct from those for a variety of neurochemical substances, although it is the same as that for norepinephrine (7). However, measurements in behaving rats have revealed that rapid dopamine changes are usually accompanied by other rapid changes in the electrochemical signal (5,8,9).…”

Cyclic Voltammetric Measurements of Neurotransmitters

“…As such, later approaches focused on continued excursions to more moderate anodic potential limits (~1.4 V) during the measurement, which maintained sensitivity but at the expense of selectivity. [12][13][14] A second modification to increase selectivity was the use of a perfluorinated ion-exchange membrane (i.e., Nafion) on the electrode surface. 15,16 The negatively charged polymer membrane acts to filter out anions (e.g., ascorbic acid and DOPAC at physiological pH), preventing their access to the electrode surface.…”

Instrumentation for fast-scan cyclic voltammetry combined with electrophysiology for behavioral experiments in freely moving animals

“…Second, a longer holding period between cyclic voltammograms facilitates dopamine adsorption, promoting sensitivity. 8 Note that in the combined mode the potential of the carbon-fiber microelectrode is allowed to float, and adsorption of dopamine occurs to a lesser extent. Nevertheless, response to dopamine for combined technique is around 60% of response observed with traditional in vivo voltammetry when electrode is held for 100 milliseconds at negative potential between scans.…”

“…FSCV has been used to detect dopamine release at the terminal fields of dopaminergic neurons in the striatum during such behaviors. 7 Technical advances in the construction of miniaturized and highly sensitive electronics as well as improvement in chemical sensitivity of the microelectrodes 8,9 have made it possible to measure endogenous dopamine release in freely moving animals routinely, allowing the study of behavior associated with this release.…”