Sulfo-Cy7.5 carboxylic acid, a dye derivative of Cyanine 7.5 (Cy7.5), features carboxylic acid and sulfonate ion (sulfonate) functional groups. The presence of the sulfonate ion enhances the compound's water solubility, making it suitable for aqueous solutions. Cy7.5, a near-infrared fluorescent dye, is frequently employed in biomedical research, including biomarkers and cell imaging. This compound can be covalently bound to biomolecules (especially antibodies, proteins, etc.) to monitor their location and dynamic changes in biological samples.