Used extensively in biological imaging and diagnostics, this compound is a key tool in fluorescence labeling. Its structure allows for efficient conjugation with biomolecules, making it ideal for tracking cellular processes and molecular interactions. The PEG4 spacer enhances solubility and reduces non-specific binding, while the Cy5 fluorophore provides strong fluorescence in the near-infrared range, enabling deep tissue imaging. It is commonly employed in flow cytometry, microscopy, and in vivo imaging studies to visualize and analyze biological systems with high precision. Additionally, its hydroxyl group facilitates further functionalization, broadening its application in bioconjugation and targeted drug delivery research.