Ion-channel Sensors Based on ETH 1001 Ionophore Embedded in Charged-alkanethiol Self-assembled Monolayers on Gold Electrode Surfaces

An ion-channel sensor was demonstrated by immobilizing ETH 1001, an ionophore for ion-selective electrodes, on a gold electrode surface. The approach for preparing the sensor was to incorporate the ionophore into a mixed self-assembled monolayer of 10-mercaptodecanesulfonate and 11-hydroxy-1-undecanethiol formed on the surface. The voltammetric responses for the thus prepared sensor to the primary cation Ca2+ were observed by using [Fe(CN)6]3-/4- as an electroactive marker. The ionophore was stably immobilized on the electrode surface with the hydrophobic interaction between its alkyl chains and those of the alkanethiol. The introduction of a proper charge density to the electrode surface improved the sensor sensitivity with retaining the selective response to Ca2+ against Mg2+ with concentrations above 10-4 M.