Zhegalova Natalia G, He Shawn, Zhou Haiying, Kim David M, Berezin Mikhail Y
Department of Radiology, Washington University School of Medicine in St Louis, St Louis, MO, 63110, USA.
Contrast Media Mol Imaging. 2014 Sep-Oct;9(5):355-62. doi: 10.1002/cmmi.1585. Epub 2014 Apr 25.
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.
即使在低浓度下，染料的自聚集也给制备用于体内成像的足够明亮的分子探针带来了相当大的挑战，特别是在将近红外花菁染料与具有多个标记位点的多肽进行缀合时。这种自聚集导致染料之间发生显著的能量转移，从而导致靶向探针严重猝灭且亮度较低。为了解决这个问题，我们设计了一种新型的具有不对称电荷分布的染料。不对称分布可防止发色团发生π堆积，从而将能量转移和荧光猝灭降至最低。该染料与多肽的缀合在吸收光谱中仅显示出少量的H聚集体带，因此具有相对较高的量子效率。
