An All-solid-state Polymeric Membrane Ca2+-selective Electrode Based on Hydrophobic Alkyl-chain-functionalized Graphene Oxide

An all-solid-state polymeric membrane Ca2+-selective electrode based on hydrophobic octadecylamine-functionalized graphene oxide has been developed. The hydrophobic composite in the ion-selective membrane not only acts as a transduction element to improve the potential stability for the all-solid-state Ca2+-selective electrode, but also is used to immobilize Ca2+ ionophore with lipophilic side chains through hydrophobic interactions. The developed all-solid-state Ca2+-selective electrode shows a stable potential response in the linear range of 3.0x10(-7)-1.0x10(-3)M with a slope of 24.7 +/- 0.3mV/dec, and the detection limit is (1.6 +/- 0.2 )x10(-7)M (n=3). Additionally, due to the hydrophobicity and electrical conductivity of the composite, the proposed all-solid-state ion-selective electrode exhibits an improved stability with the absence of water layer between the ion-selective membrane and the underlying glassy carbon electrode. This work provides a simple, efficient and low-cost methodology for developing stable and robust all-solid-state ion-selective electrode with ionophore immobilization.