Robust single-piece all-solid-state potassium-selective electrode with monolayer-protected Au clusters

High stability of the signal and simplicity in fabrication of the device are the two important requirements in development of potentiometric sensors. A robust single-piece all-solid-state potassium-selective electrode (K-SPE) was developed by incorporating monolayer-protected Au clusters (MPCs) as advanced ion-to-electron transducers into a conventional ion-selective membrane (ISM). The extraordinary properties of MPCs such as high solubility, profound hydrophobicity and large capacitance make them quite suitable to be used in fabrication of single-piece electrodes (SPEs) with advanced performance. The developed KSPEs containing small amount of MPCs in the membrane showed a significant increase in the potential stability (12.9 μV/h), lower detection limit (10-6.1 M) and prolonged life time (high performance still after 3 weeks). The multi-valence MPCs in the membrane facilitated the ion-to-electron transduction and fast establishment of the potential equilibrium resulting in fast response time in potential measurements. The inserted MPCs did not cause any interference either in the potential formation process or in the selectivity of the ion-selective membrane.