Amphotericin B ion channel mimetic sensor: A new type of potassium-selective sensor based on electrode-supported hybrid bilayer membranes

Abstract

Here, we present a new strategy to develop an ion channel mimetic sensor for sensing potassium ion, based on the amperometric response of Amphotericin B (AmB) ion channels embedded in gold electrode-supported hybrid bilayer membranes (HBMs). The reconstitution of ion-conducting AmB aqueous channels (AmBaq-pores) in HBMs, in the presence of ergosterol and high concentration of AmB, has been proved by the characterizations including cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy. Electrochemical measurements of AmBaq-pores embedded HBMs reveal the behaviors of potassium-selective and voltage-gated ion channels with open and close states, indicating their great potential for the transducer of sensor. These channels allow the hydrophilic pore-mediated transport of K+ ions toward the electrode surface, at an external negative applied potential. Amperometric i–t curve is recorded in a 50mM Tris–HCl buffer solution at pH 7.2 at an applied potential of −200mV. The currents are linearly increased with the addition of K+ in the solution from 3.5×10−6molL−1 to 1.5×10−2molL−1, and obviously inhibited if tetraethylammonium chloride (TEA) – a potassium channel blocker is added. The detection limit is determined to be 4.8×10−7molL−1. No obvious interference is observed from clinical concentrations of Ca2+, Na+, NH4+ and other main electrolytes in typical clinical samples. The performance of the sensor to the rapid and direct determination of K+ in human serum and mineral water gives satisfied results, which agree fairly well with those obtained by flame photometry.