Investigation of the enhanced signals from cations and dopamine in electrochemical sensors coated with Nafion

An electrochemical sensor for the detection of dopamine (DA) was designed using a modified Nafion membrane on a glassy carbon electrode. The electrochemical signals from dopamine were enhanced more than 10-fold on a Nafion membrane coated electrode relative to a bare electrode. The hypothesis that the origin of the signal enhancement was due to the accumulation of cationic dopamine in the Nafion was tested using Pd ions as an analog which undergo a two electron reduction similar to dopamine. Electroless deposition of palladium was used to deposit palladium on a highly oriented pyrolytic graphite surface with and without the Nafion membrane. Using scanning electron microscopy (SEM) significantly greater deposits of metallic Pd were observed on the Nafion coated surfaces than in the absence of Nafion and energy dispersive X-ray spectroscopy (EDS) confirmed quantitatively greater Pd deposition on the Nafion coated surfaces.