Sulfo-Cy5 ethylenediamine is widely used in biomedical research as a fluorescent labeling agent. Its primary application is in the labeling of proteins, peptides, and antibodies for imaging and detection purposes. The sulfo group enhances its water solubility, making it suitable for use in aqueous environments, such as biological assays and live-cell imaging. It is particularly valuable in fluorescence microscopy, flow cytometry, and in vivo imaging studies due to its near-infrared emission, which allows for deep tissue penetration and minimal background interference. Additionally, it is employed in the development of diagnostic tools and probes for studying molecular interactions and cellular processes. Its stability and bright fluorescence make it a preferred choice for sensitive and high-resolution imaging applications.