Dextran-CY5.5 is a conjugate of Dextran labeled with CY5.5. CY5.5 is a cyanine dye (with excitation and emission wavelengths typically at 673 nm and 707 nm, respectively) utilized for labeling proteins, antibodies, and small molecule compounds. Dextran inhibits platelet aggregation and coagulation factors, serving as a plasma volume expander.