This chemical is primarily used in bioconjugation and labeling applications due to its unique properties. It is often employed in the development of fluorescent probes for biological imaging, particularly in live-cell imaging and tracking studies. The propargyl-PEG4 groups allow for efficient click chemistry reactions, enabling the attachment of the Cy5 dye to various biomolecules such as proteins, peptides, or nucleic acids. This makes it valuable in studying molecular interactions, cellular processes, and drug delivery mechanisms. Additionally, its chloride form enhances solubility, making it suitable for use in aqueous environments commonly encountered in biological research.