Sulfo-Cy5.5, SE is widely used in biological research for labeling proteins, peptides, and nucleic acids due to its water solubility and near-infrared fluorescence properties. It is particularly valuable in fluorescence imaging, flow cytometry, and microscopy, enabling the visualization and tracking of biomolecules in live cells and tissues. Its stability and minimal interference with biological processes make it suitable for long-term imaging studies. Additionally, it is employed in drug development for monitoring drug delivery and targeting efficiency in preclinical models. The dye’s high sensitivity and low background noise enhance the accuracy of diagnostic assays and molecular detection techniques.