Widely used in molecular biology and immunology for detection and visualization of biomolecules. The biotin component binds strongly to streptavidin or avidin, which are often conjugated to enzymes or solid supports, enabling highly sensitive detection systems. The 5-fluorescein moiety provides a fluorescent signal, allowing direct visualization under fluorescence microscopy or detection by flow cytometry and fluorescence plate readers. Commonly applied in techniques such as ELISA, Western blotting, immunofluorescence, and in situ hybridization. Also used in affinity purification followed by fluorescent detection. Its dual functionality combines the amplification potential of the biotin-streptavidin system with the sensitivity of fluorescence, making it ideal for tracing low-abundance targets in cells and tissues.