摘要:本文基于G-四链体结构和DNA长距自组装技术,构建一种非标记型电化学交流阻抗方法用于铽离子的痕量检测.首先,根据Tb3+诱导单链DNA折叠成G-四链体的性质,设计一组捕获探针(Cp)和信号探针(Tp)序列,组装到电极表面,当Tb3+存在时,诱导Tp从双链结构中解离并折叠成G-四链体,导致电极表面的Cp裸露,进而与辅助探针Ap1、Ap2进行级联式杂交,在电极表面形成长距"三明治"DNA结构,通过电化学交流阻抗技术检测Tb3+加入前后Ret值的变化,实现对Tb3+的超高灵敏检测.在1.0×10-15M~1.0×10-12M范围内,?Ret与Tb3+浓度的对数呈良好的线性关系,方法检测限为3.4×10-16M.将其应用于实际样品中铽离子的痕量检测,结果令人满意.%In this paper,a label free electrochemical impedance spectroscopy(Ret)method was developed based on G-quadrupole structure and DNA long-distance self-assembly technique for Tb3+trace detection. First,a set of capture probes(Cp)and signal probe(Tp)sequences were designed and assembled to the electrode surface. In the presence of Tb3+,it was folded with Tp to form G-quadruplex,resulting in exposing Cp to the surface of the electrode so to be hybrid-ized with the auxiliary probes Ap1 and Ap2,which formed a long distance"sandwich"DNA structure.Using this strategy, the Ret changed linearly along with the concentrations of Tb3+.The linear range was 1.0×10-15to 1.0×10-12M with a detec-tion limit of 3.4×10-16M.