A Nafion and Choline Bi-layer Modified Carbon Fiber Electrode for In-vivo Detection of Dopamine in Mouse Cerebrum

Consisting of a choline (Ch) covalently grafted carbon fiber electrode was prepared, which was then covered by a thin layer of Nafion, forming a bi-layer modified electrode, Nafion/Ch/CFE. The electrochemical behavior of dopamine (DA) in this prepared electrode was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). For DPV determination, the electrode can be used to determine DA with no interference from DOPAC and ascorbic acid (AA). In the presence of 1.0 mM AA, a linear range of 0.38–16 μM was obtained with the detection limit (S/N = 3) of 0.1 μM DA in the electrode with 5-mm column length. The electrode was applied for the in-vivo determination of DA in the striatum area of cerebrum of living mice. The variation of DA level after a mainline of L-DOPA was recorded. Prompt pulse release of DA for acupuncturing at “Fengfu” site of the skull was observed. The advantage of the electrode was attributed to the composite structure of negatively charged Nafion and positively charged Ch modified layers.