This chemical is widely used in bioconjugation applications, particularly for labeling proteins, peptides, antibodies, and amine-modified nucleic acids. Its NHS ester groups enable efficient covalent attachment to primary amines, while the PEG4 spacer enhances solubility and reduces steric hindrance, ensuring optimal binding and labeling efficiency. The Cy5 fluorophore allows for fluorescence detection and imaging, making it valuable in fluorescence microscopy, flow cytometry, and in vivo imaging studies. It is also employed in the development of diagnostic assays and drug delivery systems, where precise tracking and visualization of biomolecules are essential. Additionally, its water solubility and biocompatibility make it suitable for use in biological and biomedical research.