Disposable-micropipette tip supported electrified liquid-organogel interface as a platform for sensing acetylcholine

Sensing acetylcholine has been predominantly based on enzymatic strategies using acetylcholine esterase and choline oxidase because of its electrochemical inertness. Electrified liquid-liquid interfaces are not limited to oxidation/reduction processes, and can be utilized to detect non-redox molecules which cannot be detected using conventional solid electrodes. In this study, a disposable micropipette tip based liquid-organogel interface, in the presence/absence of calixarene has been developed as a platform for sensing acetylcholine. We also explored a liquid-liquid interface approach for sensing acetylcholine using a pre-pulled glass micropipette. In both approaches, the configuration, i.e., liquid-organogel and liquid-liquid interface-current linearly increases during the backward transfer of acetylcholine. The simple and facilitated ion transfer of acetylcholine across the liquid-organogel exhibited a linear range of 10-50 mu M and 1-30 mu M with a detection limit of 0.18 mu M and 0.23 mu M and a sensitivity of 9.52 nA mu M-1 and 9.20 nA mu M-1, respectively. Whereas, the detection limit of simple and facilitated ion transfer of liquid-liquid interface using pre-pulled glass micropipette was found to be 0.42 mu M and 0.13 mu M with a sensitivity of 5 x 10(-3) nA mu M-1 and 3.39 x 10(-2) nA mu M-1. The results indicate that the liquid-organogel configuration supported on a disposable micropipette tip without any pre-fabrication is highly suitable for electrified soft interface sensing applications.