Department of Chemistry, University of Miami , 1301 Memorial Drive, Coral Gables, Florida 33146, United States.
J Phys Chem B. 2013 Oct 10;117(40):12000-6. doi: 10.1021/jp406993m. Epub 2013 Sep 30.
The photophysical properties of two recently reported live cell compatible, DNA-binding dyes, 4,6-bis(4-(4-methylpiperazin-1-yl)phenyl)pyrimidin-2-ol, 1, and [1,3-bis[4-(4-methylpiperazin-1-yl)phenyl]-1,3-propandioato-κO, κO']difluoroboron, 2, are characterized. Both dyes are quenched in aqueous solutions, while binding to sequences containing only AT pairs enhances the emission. Binding of the dyes to sequences containing only GC pairs does not produce a significant emission enhancement, and for sequences containing both AT and GC base pairs, emission is dependent on the length of the AT pair tracts. Through emission lifetime measurements and analysis of the dye redox potentials, photoinduced electron transfer with GC pairs is implicated as a quenching mechanism. Binding of the dyes to AT-rich regions is accompanied by bathochromic shifts of 26 and 30 nm, respectively. Excitation at longer wavelengths thus increases the ON/OFF ratio of the bound probes significantly and provides improved contrast ratios in solution as well as in fluorescence microscopy of living cells.
本文对两种最近报道的适用于活细胞的 DNA 结合染料，4,6-双（4-（4-甲基哌嗪-1-基）苯基）嘧啶-2-醇（1）和[1,3-双[4-（4-甲基哌嗪-1-基）苯基]-1,3-丙二氧基-κO,κO']二氟硼酸（2）的光物理性质进行了研究。这两种染料在水溶液中都被猝灭，而与仅含 AT 对的序列结合则增强了发射。与仅含 GC 对的序列结合不会产生显著的发射增强，而对于同时含有 AT 和 GC 碱基对的序列，发射取决于 AT 对的长度。通过发射寿命测量和染料氧化还原电位分析，发现与 GC 对的光诱导电子转移是猝灭机制之一。染料与富含 AT 的区域结合时，分别发生 26nm 和 30nm 的红移。因此，在较长波长下激发会显著增加结合探针的 ON/OFF 比值，并在溶液中和活细胞荧光显微镜中提供更好的对比度。
