Dual Sensor for Cd(II) and Ca(II): Selective Nanoliter-Scale Sensing of Metal Ions

The first selective, dual sensor for Ca2+ and Cd2+ capable of detection at 100 pM concentrations was designed and synthesized. The experimental observations made for the MC-cation complexes and the selectivity of compounds 1 and 2 with Ca2+ and Cd2+ ions were further explored using density functional theory. A first step toward a nanoliter-scale dip sensor for the dual sensing of Ca2+ and Cd2+ was demonstrated using microstructured optical fiber as the sensing platform which is important for ion sensing in confined spaces such as the medium surrounding cell clusters. In addition, this system displays picomolar sensitivity for these ions, with an added ability to reproducibly turn ion-binding on/off.