ABSTRACT
A useful ion-selective material includes any substance that alters physical or chemical properties in a quantitative, reversible fashion when it interacts with an ion. In addition it should usually display selective properties to a particular ionic species. Many ionselective materials are diffusible and thus are particularly useful in confined spaces such as the intracellular compartments of cells. Examples of such ion-selective materials include compounds which change their absorbance or fluorescence properties when an ion is bound.
