Sulfo-Cy5 diacid is widely used in bioimaging and molecular labeling due to its strong fluorescence in the near-infrared region. It is particularly valuable in fluorescence microscopy, flow cytometry, and in vivo imaging, as it allows for deep tissue penetration with minimal background interference. The compound is often conjugated to antibodies, peptides, or other biomolecules to track cellular processes, protein interactions, and disease markers. Its water solubility, enhanced by the sulfonate groups, makes it suitable for use in aqueous biological systems. Additionally, it is employed in diagnostic assays and drug development studies to visualize and quantify biological targets with high sensitivity and specificity.