Cy5.5 NHS ester (non-sulfonated)

Cyanine5.5 NHS ester is a reactive dye for the labeling of peptides, proteins, and oligonucleotides that contain amino-groups. Cy5.5-NHS ester is a near-infrared fluorescence dye able to dissolve in DMF and DMSO with the excitation maximum and emission maximum around 675 nm and 693 nm respectively [1]. The reagent is not only used for labeling moleculars contain amino groups but also used for labeling plasmid DNA [2].For biomolecule labeling, the labeling reagent has low aqueous solubility, using of organic co-solvent to dissolve this molecular is necessary for efficient reaction. First, Cyanine dye should be dissolved in organic solvent and then added to a solution of biomolecule in appropriate aqueous buffer.

Through the optical imaging of subcutaneous tumor xenografted mice, the subcutaneous U87MG tumor could be clearly distinguished from the surrounding background tissue from 30 min up to 24 h postinjection of 0.5 nmol Cy5.5-NHS. The tumor uptake of Cy5.5-NHS reached a maximum 30 minutes postinjection and slowly washed out over time [3].

References:
[1].  Ju Hee Ryu, Jin Hee Na, Ho Kyung Ko, et al. Non-invasive optical imaging of cathepsin B with activatable fluorogenic nanoprobes in various metastatic models. Biomaterials, 2014, 35: 2302-2311.
[2].  Laura-Lee Farrell, Joel Pepin, Cezary Kucharski, et al. A comparison of the effectiveness of cationic polymers poly-L-lysine (PLL) and polyethylenimine (PEI) for non-viral delivery of plasmid DNA to bone marrow stromal cells (BMSC). European Journal of Pharmaceutics and Biopharmaceutics, 2007, 65: 388–397.
[3].  Zhen Cheng, Jelena Levi, Zhengming Xiong, et al. Near-Infrared Fluorescent Deoxyglucose Analog for Tumor Optical Imaging in Cell Culture and in Living Mice. Bioconjug Chem., 2006, 17(3):662-669.