Cy5.5-PEG-NH2 (MW 2000) is a polyethylene glycol derivative that integrates the Cy5.5 fluorescent dye, polyethylene glycol (PEG), and an amino group. The Cy5.5 fluorophore is commonly utilized in applications such as immunolabeling and nucleic acid labeling, with a maximum emission wavelength of approximately 710 nm. This compound is applicable in fluorescence imaging, fluorescent tracing, and fluorescent labeling.