Cyanine3 NHS ester is widely used in the field of biomedical research and diagnostics due to its fluorescent properties. It is commonly employed as a labeling reagent for proteins, peptides, antibodies, and other biomolecules. The NHS ester group allows for efficient conjugation with primary amines, enabling stable covalent bonding to target molecules. This makes it particularly useful in fluorescence microscopy, flow cytometry, and immunoassays, where it helps visualize and track biological processes in real-time. Additionally, it is utilized in molecular imaging and in vitro studies to monitor cellular interactions, protein localization, and dynamics. Its bright fluorescence and photostability make it a preferred choice for sensitive detection and analysis in various experimental setups.