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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
Author(s) -
Hong Yuning,
Häußler Matthias,
Lam Jacky W. Y.,
Li Zhen,
Sin King Keung,
Dong Yongqiang,
Tong Hui,
Liu Jianzhao,
Qin Anjun,
Renneberg Reinhard,
Tang Ben Zhong
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701723
Subject(s) - chemistry , fluorescence , bathochromic shift , intramolecular force , g quadruplex , aqueous solution , tetraphenylethylene , folding (dsp implementation) , aggregation induced emission , dna , photochemistry , combinatorial chemistry , stereochemistry , organic chemistry , biochemistry , physics , quantum mechanics , electrical engineering , engineering
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‐triethylammonioethoxy)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.