Cy3-PEG-biotin (MW 5000) is a polyethylene glycol derivative comprising Cy3 fluorescent dye, polyethylene glycol (PEG), and biotin. Cy3 fluorophore is frequently used for applications such as immunolabeling, nucleic acid labeling, fluorescence microscopy, and flow cytometry, with a maximum emission wavelength of approximately 562-570 nm. Biotin can bind with high affinity to streptavidin or avidin. Cy3-PEG-biotin (MW 5000) plays a critical role in the specific capture and detection of biomolecules.