NN'-bis-(azide-PEG3)-Cy5 is widely used in bioimaging and bioconjugation applications due to its fluorescent properties and reactive azide groups. It is particularly valuable in labeling biomolecules such as proteins, peptides, and nucleic acids for visualization in live-cell imaging and fluorescence microscopy. The azide groups enable efficient click chemistry reactions, allowing for specific and stable conjugation with alkyne-containing molecules. This chemical is also employed in the development of fluorescent probes for studying cellular processes, tracking molecular interactions, and monitoring drug delivery systems. Its water solubility, enhanced by the PEG spacer, makes it suitable for use in aqueous biological environments.