Na+-sensing quantum dots for cell-based screening of intracellular Na+ concentrations ([Na+]i)

We have developed a Na-quantum dot (QD) nanosensor for [Na+]i measurements. Using this Na-QD, we determined the dynamic physiological responses of [Na+]i in nonexcitable human HEK-293F cells and excitable primary rat cardiac myocytes by pharmacologically manipulating the membrane permeability to Na+, the Na-K-2Cl cotransporter, and the Na+/H+ antiporter. These data suggest that the mechanisms of [Na+]i homeostasis can now be elucidated with this novel Na-QD nanosensor. This could have a broad impact on Na+ channel drug discovery.