The Filipin complex is primarily used in biological research as a fluorescent stain to detect and visualize cholesterol in cell membranes. It binds specifically to unesterified cholesterol, making it a valuable tool for studying cholesterol distribution and dynamics in cellular systems. This application is particularly useful in research related to lipid rafts, membrane organization, and diseases associated with cholesterol metabolism, such as Niemann-Pick disease. Additionally, it is employed in histochemistry to identify cholesterol accumulation in tissues, aiding in the diagnosis and study of various pathological conditions.