Used primarily as a fluorescent probe for detecting intracellular sodium ion (Na⁺) concentrations in live cells. Its fluorescence intensity changes in response to Na⁺ binding, allowing researchers to monitor sodium dynamics in real time during physiological and pathological processes. Commonly applied in neuroscience and cell biology to study ion transport, membrane potential changes, and cellular signaling. Compatible with fluorescence microscopy and plate reader systems, making it suitable for both imaging and quantitative assays. Often used in combination with other ion indicators to simultaneously track multiple ions within the same cellular environment.