Minimization of self-quenching fluorescence on dyes conjugated to biomolecules with multiple labeling sites via asymmetrically charged NIR fluorophores.

Natalia G Zhegalova, Shawn He, Haiying Zhou, David M Kim, Mikhail Y Berezin

Index: Contrast Media Mol. Imaging 9(5) , 355-62, (2014)

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Abstract

Self-aggregation of dyes even at low concentrations poses a considerable challenge in preparing sufficiently bright molecular probes for in vivo imaging, particularly in the conjugation of near infrared cyanine dyes to polypeptides with multiple labeling sites. Such self-aggregation leads to a significant energy transfer between the dyes, resulting in severe quenching and low brightness of the targeted probe. To address this problem, we designed a novel type of dye with an asymmetrical distribution of charge. Asymmetrical distribution prevents the chromophores from π-stacking thus minimizing the energy transfer and fluorescence quenching. The conjugation of the dye to polypeptides showed only a small presence of an H-aggregate band in the absorption spectra and, hence, a relatively high quantum efficiency.Copyright © 2014 John Wiley & Sons, Ltd.