Label-free fluorescent probing of G-quadruplex formation and real-time monitoring of DNA folding by a quaternized tetraphenylethene salt with aggregation-induced emission characteristics
Label-free fluorescent probing of G-quadruplex formation and real-time monitoring of DNA folding by a quaternized tetraphenylethene salt with aggregation-induced emission characteristics
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DOI：
10.1002/chem.200701723
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发表时间：
2008-01-01
影响因子：
4.3
通讯作者：
Tang, Ben Zhong
中科院分区：
文献类型：
--
作者：
Hong, Yuning;Haeussler, Matthias;Tang, Ben Zhong
诸如分子信标的生物传感过程需要非平凡的努力来共价标记或标记生物分子。我们在这里报告了一个无标记的DNA检测系统与一个简单的染料与聚集诱导发射（AIE）的特性作为荧光生物探针。1，1，2，2-四[4-（2-溴乙氧基）苯基]乙烯在溶液中不发射，但聚集时变得高度发射。这种AIE效应是由分子内旋转的限制引起的，如通过增加1，1，2，2-四[4-（2-三乙基-铵乙氧基）苯基]乙烯四溴化物（TTAPE）的水性缓冲溶液的粘度和降低温度而使发射强度大幅增加所证实的。当TTAPE通过静电引力与富含鸟嘌呤的DNA链（G1）结合时，其分子内旋转受到限制，发射开启。当竞争性阳离子加入G1溶液时，TTAPE脱离，发射关闭。TTAPE作为一种敏感的后染色剂，用于G1的聚丙烯酰胺凝胶电泳（PAGE）可视化。该染料对G1的二级结构具有高度亲和力，称为G-四链体。在G1折叠过程中涉及的红移允许光谱歧视的G-四链体从其他DNA结构。TTAPE染料对G-四链体结构的强亲和力与静电吸引辅助的几何拟合相关。TTAPE独特的AIE功能使其能够在DNA链上没有任何预先连接的荧光标记的情况下实时监测G1的折叠过程。TTAPE对K+诱导和稳定的四链体结构具有特异性，可用作K+离子生物传感器。
Biosensing processes such as molecular beacons require non-trivial effort to covalently label or mark biomolecules. We report here a label-free DNA assay system with a simple dye with aggregation-induced emission (AIE) characteristics as the fluorescent bioprobe. 1,1,2,2-Tetrakis[4-(2-bromoethoxy)phenyl]ethene is nonemissive in solution but becomes highly emissive when aggregated. This AIE effect is caused by restriction of intramolecular rotation, as verified by a large increase in the emission intensity by increasing viscosity and decreasing temperature of the aqueous buffer solution of 1,1,2,2-tetrakis[4-(2-triethyl-ammonioethoxy)phenyl]ethene tetrabromide (TTAPE). When TTAPE is bound to a guanine-rich DNA strand (G1) via electrostatic attraction, its intramolecular rotation is restricted and its emission is turned on. When a competitive cation is added to the G1 solution, TTAPE is detached and its emission is turned off. TTAPE works as a sensitive poststaining agent for poly(acrylamide) gel electrophoresis (PAGE) visualization of G1. The dye is highly affinitive to a secondary structure of G1 called the G-quadruplex. The bathochromic shift involved in the G1 folding process allows spectral discrimination of the G-quadruplex from other DNA structures. The strong affinity of TTAPE dye to the G-quadruplex structure is associated with a geometric fit aided by the electrostatic attraction. The distinct AIE feature of TTAPE enables real-time monitoring of folding process of G1 in the absence of any pre-attached fluorogenic labels on the DNA strand. TTAPE can be used as a K+ ion biosensor because of its specificity to K+-induced and -stabilized quadruplex structure.