Cy3 carboxylic acid (non-sulfonated)

Cy3 carboxylic acid is a non-activated fluorescence dye. Most derivatives of non-sulfonated cyanines have low aqueous solubility except for hydrochlorides of hydrazides and amines. This Non-sulfonated reagent has limited aqueous solubility, but with good solubility in organic solvents. 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.

In the supramolecular glutamine assay, Cy3 carboxylic acid was conjugated to a single strain DNA and then immobilized onto the glass slide through DNA hybridization. The Cy3 groups serve as FRET donor and the cyclodextrins as supramolecular host [1].

Reference:
[1] Xue, M. ; Wei, W.; Su, Y.; Johnson, D.; Heath, J.R. Supramolecular Probes for Assessing Glutamine Uptake Enable Semi-Quantitative Metabolic Models in Single Cells. Journal of the American Chemical Society, 2016, 138(9), 3085–3093.