Cy7.5 carboxylic acid (non-sulfonated)

Cy7.5 carboxylic acid is a free un-activated NIR dye which has low aqueous solubility. As for coupling and labeling reactions, pre-activated Cy7 NHS ester or water-soluble sulfo-Cy7 NHS ester would be considered. For biomolecule labeling, the labeling regent 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.

In mice, near-infrared labeling of the materials allowed for non-invasive imaging of the injected hydrogel. Cy7.5 carboxylic acid labeled images can demonstrate localization of the injected hydrogel to the affected kidney. Moreover, the methodology allowed direct quantification of material degradation in vivo [1].

Reference:
[1].  Rodell, C.B.; Rai, R.; Faubel, S.; Burdick, J.A.; Soranno, D.E. Local Immunotherapy via Delivery of Interleukin-10 and Transforming Growth Factor β Antagonist for Treatment of Chronic Kidney Disease. Journal of Controlled Release, 2015, 206, 131–139.