Oxonol Yellow K is widely used as a fluorescent dye in biological research, particularly for staining and imaging applications. It is commonly employed to monitor membrane potential in cells, as it can selectively accumulate in depolarized membranes, making it a valuable tool in electrophysiology and cell biology studies. Additionally, it is utilized in flow cytometry to assess cell viability and function. Its ability to emit strong fluorescence under specific conditions makes it suitable for detecting changes in cellular environments, aiding in the study of mitochondrial activity and apoptosis. The dye is also used in combination with other probes for multi-parameter analysis in complex biological systems.