中文摘要：

该研究以小分子可卡因为检测模型，报道了一种基于等温循环链置换聚合的无需标记且具有通用性的荧光生物传感系统。当目标小分子可卡因存在时，该适体探针形成与目标分子特异性结合的空间结构，其两端的发夹结构被打开，留出可以与引物杂交的3’端，在Klenow聚合酶的作用下发生等温聚合反应形成双链。置换出来的目标分子又可以与适体探针结合进行下一轮反应。如此循环，通过荧光染料嵌入双链产物可以实现对目标分子的非标记高灵敏检测。在优化的实验条件下，该传感系统在5nmol/L～50μmol／L的范围内对可卡因有良好的线性。通过巧妙设计适体探针，该传感系统可以作为一种通用型方法用于其它目标物的分析。

英文摘要：

A label-free and universal fluorescent biosensing system based on isothermal circular strand-displace- ment polymerization （ICSDP） was proposed in the study, using cocaine as the model analyte. The aptamer probe changed its structure to specifically bind with the target molecule. The hairpin in 3＇ terminal of the aptamer was opened and bond with primer, which triggered ICSDP and formed DNA duplex in the presence of Klenow ploymerase. The target molecule was released for another circular reaction. By intercalating with fluorescent dye of SYBR Green I, significant fluorescent signal could be detected and the target molecule could be sensitively detected with a linear range of 5 nmol/L to 50 μmol/L under optimized experimental conditions. Moreover, the presented biosensing system is universal for analysis of other target molecules by skillfully changing and designing its aptamer probe.