Zinquin ethyl ester is widely used as a fluorescent probe for the detection and visualization of zinc ions in biological systems. Its ability to selectively bind to free or loosely bound zinc makes it a valuable tool in cellular and molecular biology research. Scientists utilize it to study zinc homeostasis, distribution, and its role in various physiological processes, including neurotransmission, immune function, and apoptosis. In neuroscience, it helps map zinc-rich regions in the brain, particularly in synaptic vesicles, providing insights into zinc's role in neural signaling. Additionally, it is employed in medical research to investigate zinc-related pathologies, such as neurodegenerative diseases and diabetes. Its fluorescence properties enable real-time imaging and quantification of zinc dynamics in live cells and tissues, making it a critical reagent in advancing our understanding of zinc biology.