Cy5, SE is widely used in biological research for labeling proteins, peptides, and nucleic acids. Its near-infrared fluorescence makes it ideal for imaging and detection in complex biological samples. It is commonly applied in fluorescence microscopy, flow cytometry, and in vivo imaging, providing high sensitivity and minimal background interference. The dye is also used in molecular diagnostics, such as DNA sequencing and microarray analysis, due to its stable conjugation and strong signal output. Additionally, it plays a key role in studying protein-protein interactions and cellular processes through fluorescence resonance energy transfer (FRET) techniques.