Sulfo-Cy7.5 alkyne is a derivative of Cyanine 7.5 (Cy7.5) that incorporates sulfonate ions and an alkyne functional group. The sulfonate ions enhance the compound's solubility in water, making it ideal for aqueous solutions. As a near-infrared fluorescent dye, Cy7.5 is widely used for biological labeling and cellular imaging. The alkyne group of Sulfo-Cy7.5 alkyne can react covalently with molecules containing azide groups. This allows Sulfo-Cy7.5 alkyne to bind with biomolecules such as proteins and antibodies, facilitating the tracking of their position and dynamic changes within biological samples.