Selective dopamine detection using aptamer-functionalized glassy carbon electrodes

The electrochemical detection of dopamine using glassy carbon electrodes suffers from a lack of selectivity toward the neurotransmitter, as interferences such as other catechol-containing neurochemicals and ascorbic acid can be oxidized at overlapping potentials. Several approaches have been employed to improve the selectivity of these electrodes towards dopamine including electrochemical pretreatment and organic monolayer depositions. Here, we characterize glassy carbon electrodes that were initially passivated through a trifluoromethylphenyl and nitrophenyl monolayer deposition and then functionalized with a specific DNA dopamine aptamer. Passivation with the mixed monolayer cuts off all signals from the redox-active neurochemicals. After functionalization with the DNA aptamer, the dopamine signal is restored and the electrodes are more responsive to dopamine than to any other related catechol-containing compounds or other common neurochemicals such as ascorbic acid. Our findings indicate that aptamer functionalization of glassy carbon electrodes may provide a viable approach for tuning the selectivity of electrochemical detection