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

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.
Asymmetrically charged ends of NIR fluorescent probes minimize self‐aggregation of the dye on the surfaces of the biomolecule due to electrostatic repulsion. The contrast agent shows excellent brightness.

Source: Contrast Media and Molecular Imaging - April 25, 2014 Category: Radiology Authors: Natalia G. Zhegalova, Shawn He, Haiying Zhou, David M. Kim, Mikhail Y. Berezin Tags: Full Paper Source Type: research