Enhancement of fluorescent properties of near-infrared dyes using clickable oligoglycerol dendronsElectronic supplementary information (ESI) available. See DOI: 10.1039/c5ob00299k

Near-infrared (NIR) fluorescent dyes are gaining increased attention due to their potential to serve as molecular probes for in vivo imaging. Here, we demonstrate that oligoglycerol dendrons effectively enhance the fluorescence properties of an NIR dye by increasing the solubility in water and the prevention of aggregate formation. First- and second-generation oligoglycerol dendrons were conjugated to an NIR dye via a dipolar-cycloaddition (click) reaction. The two new dye conjugates exhibited enhanced NIR fluorescent emission and considerably higher fluorescent quantum yields than the dye alone. The high photostability measured for one of the oligoglycerol-linked dyes, in comparison to commonly used fluorogenic dyes such as Cy5 and Cy7, was validated using fluorescence microscopy of macrophages. Oligoglycerol dendrons effectively enhance the fluorescence properties of a cyanine NIR dye by increasing the solubility in water and the prevention of aggregate formation.