Fluorescein biotin is widely used in molecular biology and biochemistry for labeling and detection purposes. Its applications include: - **Fluorescent Labeling**: It is commonly used to label proteins, nucleic acids, and other biomolecules for visualization under a fluorescence microscope. The fluorescein moiety provides a strong green fluorescence signal, making it ideal for tracking and imaging. - **Biotin-Streptavidin System**: The biotin component allows for strong and specific binding to streptavidin or avidin, enabling its use in affinity purification, immunoassays, and diagnostic techniques like ELISA. - **Flow Cytometry**: It is employed in flow cytometry to tag cells or particles, facilitating the analysis and sorting of specific populations based on fluorescence. - **In Situ Hybridization**: Fluorescein biotin is used in fluorescence in situ hybridization (FISH) to label DNA or RNA probes, aiding in the detection of specific genetic sequences within cells or tissues. - **Biosensors**: It is integrated into biosensor designs for detecting biomolecular interactions, leveraging its fluorescence for real-time monitoring. These applications make it a versatile tool in research, diagnostics, and biotechnology.