PBFI-AM is widely used as a fluorescent indicator for measuring intracellular potassium ion (K⁺) concentrations. It is particularly valuable in cellular and molecular biology research, where it helps study potassium dynamics in living cells. The compound enters cells easily and, once inside, is hydrolyzed to PBFI, which binds to potassium ions and exhibits a change in fluorescence intensity. This property allows researchers to monitor potassium levels in real-time, providing insights into cellular processes such as ion transport, membrane potential, and cell signaling. It is commonly applied in neuroscience, cardiology, and physiology to investigate potassium-related mechanisms in neurons, muscle cells, and other tissues.