Ion concentrations in live cells from highly selective ion correlation fluorescent nano-sensors for sodium

Fluorescent spherical nanosensors, or PEBBLEs (probes encapsulated by biologically localized embedding) in the 500 nm -1 μm size range have been developed using decyl methacrylate as a matrix. A general scheme for the polymerization and introduction of sensing components creates a matrix that allows for the utilization of the highly selective ionophores used in poly (vinyl chloride) and decyl methacrylate ion-selective electrodes. We have demonstrated that our previously developed scheme can be utilized to tailoring selective submicron sensors for use in intracellular measurements of important analytes for which selective enough fluorescent probes do not exist. The general scheme should work for any available ionophore used in PVC or decyl methacrylate ion selective electrodes, with minor adjustments to account for differences in ionophore charge and analyte binding constant. Sodium nanosensors based on the neutral ionophores monensin decyl ester and sodium ionophore IV have been developed and applied to live C6 glioma cells to demonstrate their utility; the intracellular activity of Na⁺-K⁺-Cl^-cotransport is followed in real time upon extracellular administration of kainic acid.