A Novel “Turn-On” Fluorescent Sensor for Screening Triplex DNA Binder Based upon Molecular Beacon
Graphical Triplex DNA plays an essential role in molecular recognition, gene regulation, diagnosis, and treatment of genetic diseases. It is crucial to screen intercalators to enhance triplex DNA stability. We established a novel “turn-on” fluorescence sensor for screening triplex DNA binders based upon molecular beacon and target dsDNA. The working principle of DNA fluorescence sensor was confirmed by circular dichroism experiments and melting curve tests. Triplex DNA plays an essential role in molecular recognition, gene regulation, diagnosis, and treatment of genetic diseases. However, triplex DNA has some shortcomings, such as poor internal Hoogsteen hydrogen bond stability and the difficult formation of parallel triplex DNA under physiological conditions, limiting its applications to a certain extent. Therefore, it is crucial to screen intercalators to enhance triplex DNA stability. Herein, we established a novel “turn-on” fluorescence sensor for screening triplex DNA binders based upon molecular beacon. Eight different organic small molecules were screened. The fluorescence of the sensor was significantly enhanced in the presence of berberine, coralyne, palmatine, and neomycin. These four small molecules affect stabilizing triplex DNA as an intercalator; the other four small molecules, kanamycin, tetracycline, ethidium bromide, and 4 ′, 6-diamidino-2-phenylindole did not show any noticeable intercalation effect. The results of circular dichroism and melting curve were consistent with those of the fluorescence spectrum.
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