Characterisation of carbon paste electrodes for real-time amperometric monitoring of brain tissue oxygen.
Tissue O₂ can be monitored using a variety of electrochemical techniques and electrodes. In vitro and in vivo characterisation studies for O₂ reduction at carbon paste electrodes (CPEs) using constant potential amperometry (CPA) are presented. Cyclic voltammetry indicated that an applied potential of -650 mV is required for O₂ reduction at CPEs. High sensitivity (-1.49 ± 0.01 nA/μM), low detection limit (ca. 0.1 μM) and good linear response characteristics (R² > 0.99) were observed in calibration experiments performed at this potential. There was also no effect of pH, temperature, and ion changes, and no dependence upon flow/fluid convection (stirring). Several compounds (e.g. dopamine and its metabolites) present in brain extracellular fluid were tested at physiological concentrations and shown not to interfere with the CPA O₂ signal. In vivo experiments confirmed a sub-second response time observed in vitro and demonstrated long-term stability extending over twelve weeks, with minimal O₂ consumption (ca. 1 nmol/h). These results indicate that CPEs operating amperometrically at a constant potential of -650 mV (vs. SCE) can be used reliably to continuously monitor brain extracellular tissue O₂.
Department of Chemistry, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
Fiachra B
FB
Bolger
Stephen B
SB
McHugh
Rachel
R
Bennett
Jennifer
J
Li
Keita
K
Ishiwari
Jennifer
J
Francois
Michael W
MW
Conway
Gary
G
Gilmour
David M
DM
Bannerman
Marianne
M
Fillenz
Mark
M
Tricklebank
John P
JP
Lowry
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002244:Carbon; D004298:Dopamine / Q000378:metabolism; D055664:Electrochemical Techniques / Q000295:instrumentation* / Q000379:methods*; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism; D013696:Temperature; D013997:Time Factors
D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D002244:Carbon; D010100:Oxygen; D004298:Dopamine