Cy5 is widely used in biological research as a fluorescent dye for labeling and tracking biomolecules. Its near-infrared fluorescence makes it ideal for imaging applications, as it minimizes background interference from biological samples. Cy5 is commonly employed in fluorescence microscopy, flow cytometry, and in vivo imaging to study cellular processes, protein interactions, and gene expression. It is also used in immunoassays, such as ELISA, to detect specific antigens or antibodies with high sensitivity. Additionally, Cy5 is a key component in microarray technologies, enabling the simultaneous analysis of thousands of genes or proteins. Its stability and brightness make it a preferred choice for various diagnostic and research applications.