Sulforhodamine 101 sulfonyl chloride is widely used as a fluorescent labeling reagent in biochemical and cellular research. It is particularly valued for its ability to covalently bind to proteins, peptides, and other biomolecules, enabling the visualization and tracking of these molecules in complex biological systems. This compound is often employed in fluorescence microscopy, flow cytometry, and other imaging techniques to study cellular processes, protein interactions, and localization within cells. Its bright and stable fluorescence makes it a reliable tool for labeling and detecting specific targets in live or fixed cells. Additionally, it is utilized in the development of fluorescent probes and sensors for diagnostic and research applications, providing high sensitivity and specificity in detecting biological molecules.