Cy5.5 is a near-infrared fluorescent dye for labeling biomolecules such as peptides, proteins and oligonucleotides (Ex=673 nm, Em=707 nm)[2].

METHODS: fVIIa and anti-TF antibody were labeled with the fluorescent tag Cy5.5, and U87MG-EGFRviii glioma cells were exposed to Cy5.5-labeled fVIIa and Cy5.5-labeled anti-TF antibody in vitro. To demonstrate the specificity of fVIIa binding to TF, unbound fVIIa was incubated with Cy5.5-labeled fVIIa in vitro at a 5-fold excess.
RESULTS The images obtained showed that most of the signal of Cy5.5-labeled fVIIa was reduced by adding excess unlabeled fVIIa in vitro, indicating the specificity of binding. [1]

METHODS: Cy5.5-FFRck-fVIIa and Cy5.5 dye alone were injected intravenously (i.v.) into right flank athymic nude mice (nu/nu) bearing TF-expressing ASPC-1 and TF-non-expressing MiaPaCa pancreatic tumor xenografts and tested for duration and stability of binding to enable follow-up of treatment response.
RESULTS Specific localization of Cy5.5-FFRck-fVIIa to TF in VECs of pancreatic tumor xenografts was observed from day 1 to day 26 in both ASPC-1 and MiaPaCa tumors, whereas no specific localization was observed with unconjugated Cy5.5 alone.[1]