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Sawhorse waveform voltammetry for selective detection of adenosine, ATP, and hydrogen peroxide.

Ross AE, Venton BJ - Anal. Chem. (2014)

Bottom Line: Principal component analysis (PCA) was used to determine that the sawhorse waveform was better than the triangle waveform at discriminating between adenosine, hydrogen peroxide, and ATP.In slices, mechanically evoked adenosine was identified with PCA and changes in the ratio of ATP to adenosine were observed after manipulation of ATP metabolism by POM-1.The sawhorse waveform is useful for adenosine, hydrogen peroxide, and ATP discrimination and will facilitate more confident measurements of these analytes in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Virginia , Charlottesville, Virginia 22904, United States.

ABSTRACT
Fast-scan cyclic voltammetry (FSCV) is an electrochemistry technique which allows subsecond detection of neurotransmitters in vivo. Adenosine detection using FSCV has become increasingly popular but can be difficult because of interfering agents which oxidize at or near the same potential as adenosine. Triangle shaped waveforms are traditionally used for FSCV, but modified waveforms have been introduced to maximize analyte sensitivity and provide stability at high scan rates. Here, a modified sawhorse waveform was used to maximize the time for adenosine oxidation and to manipulate the shapes of cyclic voltammograms (CVs) of analytes which oxidize at the switching potential. The optimized waveform consists of scanning at 400 V/s from -0.4 to 1.35 V and holding briefly for 1.0 ms followed by a ramp back down to -0.4 V. This waveform allows the use of a lower switching potential for adenosine detection. Hydrogen peroxide and ATP also oxidize at the switching potential and can interfere with adenosine measurements in vivo; however, their CVs were altered with the sawhorse waveform and they could be distinguished from adenosine. Principal component analysis (PCA) was used to determine that the sawhorse waveform was better than the triangle waveform at discriminating between adenosine, hydrogen peroxide, and ATP. In slices, mechanically evoked adenosine was identified with PCA and changes in the ratio of ATP to adenosine were observed after manipulation of ATP metabolism by POM-1. The sawhorse waveform is useful for adenosine, hydrogen peroxide, and ATP discrimination and will facilitate more confident measurements of these analytes in vivo.

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Comparison of currentat both the triangle and sawhorse waveformat various switching potentials. The plot shows average current foreach switching potential tested for both the triangle (black) andsawhorse (gray) waveform for 1 μM adenosine. The sawhorse waveformproduced significantly more current for adenosine than the trianglewaveform at 1.30 and 1.35 V switching potential (unpaired t test p < 0.01 and p < 0.001, respectively, n = 6).The currents for1.40 and 1.45 V were not significantly different between the sawhorseand triangle waveform (unpaired t test p > 0.05, n = 6).
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fig4: Comparison of currentat both the triangle and sawhorse waveformat various switching potentials. The plot shows average current foreach switching potential tested for both the triangle (black) andsawhorse (gray) waveform for 1 μM adenosine. The sawhorse waveformproduced significantly more current for adenosine than the trianglewaveform at 1.30 and 1.35 V switching potential (unpaired t test p < 0.01 and p < 0.001, respectively, n = 6).The currents for1.40 and 1.45 V were not significantly different between the sawhorseand triangle waveform (unpaired t test p > 0.05, n = 6).

Mentions: The sawhorse waveform produced significantly more currentfor adenosinethan the triangle waveform at 1.30 and 1.35 V switching potentials(Figure 4, unpaired t test p < 0.01 and p < 0.001, respectively).With a 1.35 V upper potential, 1.3 ± 0.3 nA/μM adenosinewas detected with the triangle waveform (n = 6),whereas 6.8 ± 1.1 nA/μM adenosine was detected with thesawhorse (n = 6); therefore, the sawhorse waveformoffers a significant, 5-fold increase in current over the trianglewaveform at 1.35 V (unpaired t test, p < 0.001, n = 6). The currents for 1.40 and 1.45V were not significantly different between the sawhorse and trianglewaveform (unpaired t test p >0.05).The limit of detection (LOD) for the triangle waveform is 34 ±10 nM with a switching potential of 1.35 V and is 21 ± 3 nM with1.45 V,18 whereas the LOD is 12 ±4 nM at the sawhorse waveform with a 1.35 V switching potential (n = 6). The LOD of the sawhorse waveform is significantlydifferent than the triangle waveform with a 1.35 V switching potential(unpaired t test, p < 0.05) butnot significantly different than the triangle waveform with a 1.45V switching potential (unpaired t test, p > 0.05). The sawhorse waveform offers more sensitivity at lowerpotentials than the triangle waveform.


Sawhorse waveform voltammetry for selective detection of adenosine, ATP, and hydrogen peroxide.

Ross AE, Venton BJ - Anal. Chem. (2014)

Comparison of currentat both the triangle and sawhorse waveformat various switching potentials. The plot shows average current foreach switching potential tested for both the triangle (black) andsawhorse (gray) waveform for 1 μM adenosine. The sawhorse waveformproduced significantly more current for adenosine than the trianglewaveform at 1.30 and 1.35 V switching potential (unpaired t test p < 0.01 and p < 0.001, respectively, n = 6).The currents for1.40 and 1.45 V were not significantly different between the sawhorseand triangle waveform (unpaired t test p > 0.05, n = 6).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4368507&req=5

fig4: Comparison of currentat both the triangle and sawhorse waveformat various switching potentials. The plot shows average current foreach switching potential tested for both the triangle (black) andsawhorse (gray) waveform for 1 μM adenosine. The sawhorse waveformproduced significantly more current for adenosine than the trianglewaveform at 1.30 and 1.35 V switching potential (unpaired t test p < 0.01 and p < 0.001, respectively, n = 6).The currents for1.40 and 1.45 V were not significantly different between the sawhorseand triangle waveform (unpaired t test p > 0.05, n = 6).
Mentions: The sawhorse waveform produced significantly more currentfor adenosinethan the triangle waveform at 1.30 and 1.35 V switching potentials(Figure 4, unpaired t test p < 0.01 and p < 0.001, respectively).With a 1.35 V upper potential, 1.3 ± 0.3 nA/μM adenosinewas detected with the triangle waveform (n = 6),whereas 6.8 ± 1.1 nA/μM adenosine was detected with thesawhorse (n = 6); therefore, the sawhorse waveformoffers a significant, 5-fold increase in current over the trianglewaveform at 1.35 V (unpaired t test, p < 0.001, n = 6). The currents for 1.40 and 1.45V were not significantly different between the sawhorse and trianglewaveform (unpaired t test p >0.05).The limit of detection (LOD) for the triangle waveform is 34 ±10 nM with a switching potential of 1.35 V and is 21 ± 3 nM with1.45 V,18 whereas the LOD is 12 ±4 nM at the sawhorse waveform with a 1.35 V switching potential (n = 6). The LOD of the sawhorse waveform is significantlydifferent than the triangle waveform with a 1.35 V switching potential(unpaired t test, p < 0.05) butnot significantly different than the triangle waveform with a 1.45V switching potential (unpaired t test, p > 0.05). The sawhorse waveform offers more sensitivity at lowerpotentials than the triangle waveform.

Bottom Line: Principal component analysis (PCA) was used to determine that the sawhorse waveform was better than the triangle waveform at discriminating between adenosine, hydrogen peroxide, and ATP.In slices, mechanically evoked adenosine was identified with PCA and changes in the ratio of ATP to adenosine were observed after manipulation of ATP metabolism by POM-1.The sawhorse waveform is useful for adenosine, hydrogen peroxide, and ATP discrimination and will facilitate more confident measurements of these analytes in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Virginia , Charlottesville, Virginia 22904, United States.

ABSTRACT
Fast-scan cyclic voltammetry (FSCV) is an electrochemistry technique which allows subsecond detection of neurotransmitters in vivo. Adenosine detection using FSCV has become increasingly popular but can be difficult because of interfering agents which oxidize at or near the same potential as adenosine. Triangle shaped waveforms are traditionally used for FSCV, but modified waveforms have been introduced to maximize analyte sensitivity and provide stability at high scan rates. Here, a modified sawhorse waveform was used to maximize the time for adenosine oxidation and to manipulate the shapes of cyclic voltammograms (CVs) of analytes which oxidize at the switching potential. The optimized waveform consists of scanning at 400 V/s from -0.4 to 1.35 V and holding briefly for 1.0 ms followed by a ramp back down to -0.4 V. This waveform allows the use of a lower switching potential for adenosine detection. Hydrogen peroxide and ATP also oxidize at the switching potential and can interfere with adenosine measurements in vivo; however, their CVs were altered with the sawhorse waveform and they could be distinguished from adenosine. Principal component analysis (PCA) was used to determine that the sawhorse waveform was better than the triangle waveform at discriminating between adenosine, hydrogen peroxide, and ATP. In slices, mechanically evoked adenosine was identified with PCA and changes in the ratio of ATP to adenosine were observed after manipulation of ATP metabolism by POM-1. The sawhorse waveform is useful for adenosine, hydrogen peroxide, and ATP discrimination and will facilitate more confident measurements of these analytes in vivo.

Show MeSH