Examining the Effects of Common Laboratory Methods on the Sensitivity of Carbon Fiber Electrodes in Amperometric Recordings of Dopamine

Abstract

Carbon fiber microelectrodes (CFEs) are useful when combined with electro-chemical techniques for measuring changes in neurotransmitter concentra-tions. We addressed conflicting details regarding the use of CFEs. Experi-mental groups consisted of CFEs at different ages (1 week, 1 month, or 2 months), cleaned in solvents (isopropanol or xylene), and exposed to in vitro use (flow cell calibrations) or in vivo use (in brain tissue). In order to deter-mine if any of these factors affect CFE sensitivity, the present study utilized fixed potential amperometry and a flow injection system to calibrate CFEs for the measurement of dopamine. The sensitivity index (nA/µM per 100 µm of exposed carbon fiber) was not affected by the age of CFEs or pre-cleaning with xylene or isopropanol. CFE sensitivity of the in vitro exposure group also did not differ from untreated CFEs, indicating the calibration process did not alter sensitivity. However, in vivo use in brain tissue did reduce sensitivity. This effect was negated and sensitivity restored by cleaning CFEs in isopro-panol or xylene following in vivo brain recordings. Given that variations in CFE sensitivity can skew results, our findings can help standardize CFE use and explain discrepancies between researchers.