Preparation of potentiometric acetylcholine sensor using electropolymerized insulating poly-1-aminopyrrole with polyion complex

A potentiometric acetylcholine microsensor was fabricated by use of a composite film consisting of polyion complex (PIC), which consisted with acetylcholine esterase (AChE), and the electrochemically inactive poly-1-aminopyrrole (iPAPy). The iPAPy-PIC (AChE) composite film on Pt electrode displayed potential response to acetylcholine concentration owing to pH change during the enzymatic reaction, where the product contains weak acid CH₃COOH. The sensitivity of the iPAPy-PIC (AChE) electrode clearly demonstrated higher sensitivity with low detection limit (1 × 10^-6 mol dm^-3) than that of the iPPy-PIC (AChE) electrode of detection limit (1 × 10^-5 mol dm^-3). The mechanism of increasing the sensitivity of iPAPy-PIC (AChE) electrode was discussed the interaction of -NH₂ of iPAPy with CH₃ COOH, which would accelerate the dissociation of weak acid CH₃COOH.