5-(Octadecanoylamino)fluorescein is primarily used as a fluorescent probe in various biochemical and cellular studies. Its application is significant in labeling and tracking lipid molecules within biological systems due to its lipophilic nature, which allows it to integrate into lipid bilayers and membranes. This property makes it useful for visualizing membrane dynamics, lipid distribution, and interactions in live cells or tissues. Additionally, it is employed in fluorescence microscopy to study lipid rafts, endocytosis, and membrane trafficking processes. The compound’s fluorescence properties also enable its use in flow cytometry and other fluorescence-based assays to analyze cellular processes involving lipids. Its ability to bind and highlight lipids provides valuable insights into lipid metabolism and membrane-related biological functions.