Monitoring the function of molecular beacon type probe at the single molecule level

合成了荧光分子特异性修饰的DNA位点。测量处于三重激发态的荧光分子的寿命，其反映在荧光闪烁期间的关闭时间的持续时间（tOFF）中。通过荧光相关光谱（FCS）测定tOFF。已经证明，荧光分子暴露于溶剂越多，其三重激发态被分子氧猝灭越快，导致tOFF降低。双链体和发夹结构之间的DNA构象变化，分子信标型探针的功能，成功地监测了由荧光分子的溶剂可及性的变化触发的闪烁。

DNA site specifically modified with fluorescent molecule were synthesized. The lifetime of a fluorescent molecule in the triplet excited state was measured, which is reflected in the duration of the off time during the blinking of the fluorescence (tOFF). tOFF was determined by fluorescence correlation spectroscopy (FCS). It was demonstrated that the more a fluorescent molecule is exposed to a solvent, the faster its triplet excited state is quenched by molecular oxygen, resulting in a decrease of tOFF. DNA conformational change between a duplex and hairpin structure, function of the molecular beacon type probe, was successfully monitored by the blinking triggered by the changes in the solvent accessibility of the fluorescent molecule.