Switches on the Two-Photon Efficiency of an Ultrabright Triphenylamine Fluorescent Probe Specific of AT Regions
Switches on the Two-Photon Efficiency of an Ultrabright Triphenylamine Fluorescent Probe Specific of AT Regions
复制标题
DOI：
10.1021/ja404422z
复制
发表时间：
2013-08-28
影响因子：
15
通讯作者：
Teulade-Fichou, Marie-Paule
中科院分区：
文献类型：
--
作者：
Dumat, Blaise;Bordeau, Guillaume;Teulade-Fichou, Marie-Paule
本文报道了以N-甲基苯并咪唑为端基的双光子荧光三苯胺的设计和合成。新化合物(TP-2Bzim，TP-3Bzim)是发光的荧光DNA探针，具有长波长发射(>；580 nm)。与它们的吡啶模型相比，TP-Bzim染料的DNA亲和力和荧光量子产率都有了显著的提高，特别是对两个分支的衍生物(TP-2Bzim：Phi(F)=0.54，k(A)=10(7)M-1)，导致了高达140的荧光发射开启比。同时，TP-2Bzim的双光子吸收截面在DNA结合后显著增强(游离型增量=1080vs110GM)。首次揭示了DNA基质对非线性吸收的影响。这归因于在圆二色谱和分子模拟数据的支持下，富含AT的DNA小槽内的分子紧密配合，导致染料基态的几何重排。因此，TP-2bzim显示出特殊的双光子分子亮度(Delta x Phi(F)=583 GM)，这一值对于小型生物荧光团来说是无与伦比的。这些特性使得能够在亚微摩尔浓度([TP-2Bzim]=100 nM)的固定细胞中成像核DNA，并观察到着丝粒丰富的AT染色质的超亮焦点。TP-2Bzim具有很高的光稳定性，是活细胞，不需要核糖核酸酶处理。这种出色的光学和生物学特性的结合使TP-2Bzim成为一种超越最好的DNA着色剂的生物探针，并为进一步研究DNA的非线性光学过程铺平了道路。
We report on the design and synthesis of two-photon fluorescent triphenylamines bearing two or three vinyl branches terminated by a N-methyl benzimidazolium moiety. The new compounds (TP-2Bzim, TP-3Bzim) are light-up fluorescent DNA probes with a long wavelength emission (>580 nm). Compared to their pyridinium models, the TP-Bzim dyes exhibit a remarkable improvement of both their DNA affinity and fluorescence quantum yield, especially for the two-branch derivative (TP-2Bzim: Phi(F) = 0.54, k(a) = 10(7) M-1), resulting in a large fluorescence emission turn-on ratio of up to 140. Concomitantly, the two-photon absorption cross-section of TP-2Bzim is dramatically enhanced upon DNA binding (delta = 1080 vs 110 GM for the free form). This effect of the DNA matrix on the nonlinear absorption is uncovered for the first time. This is attributed to a tight fit of the molecule inside the minor groove of AT-rich DNA which induces geometrical rearrangements in the dye ground state as supported by circular dichroism and molecular modeling data. Consequently, TP-2bzim displays an exceptional two-photon molecular brightness (delta x Phi(F) = 583 GM), a value unrivalled for a small biofluorophore. These properties enable to image nuclear DNA in fixed cells at submicromolar concentration ([TP-2Bzim] = 100 nM) and to visualize ultrabright foci of centromeric AT-rich chromatin. Finally TP-2Bzim exhibits a high photostability, is live-cell permeant, and does not require RNase treatment. This outstanding combination of optical and biological properties makes TP-2Bzim a bioprobe surpassing the best DNA stainers and paves the way for studying further nonlinear optical processes in DNA.