Cy5 is widely used in biological research as a fluorescent dye for labeling and imaging applications. Its strong fluorescence in the red to near-infrared range makes it ideal for detecting biomolecules in complex systems, such as proteins, nucleic acids, and cells. It is commonly employed in fluorescence microscopy, flow cytometry, and in vivo imaging due to its high sensitivity and minimal background interference. Cy5 is also used in molecular biology techniques like DNA sequencing, immunoassays, and fluorescence in situ hybridization (FISH) to visualize and track specific targets. Additionally, its compatibility with various conjugation methods allows it to be attached to antibodies, peptides, and other probes for targeted imaging and diagnostics.