The invention belongs to the nucleic acid detection technical field, in particular discloses a switch mode aptamer probe and application thereof. The aptamer probe comprises a probe body as well as a fluorescence generating unit and a fluorescence extinguishing unit which are respectively connected at the two ends of the probe body, the probe body contains an aptamer segment with specificity identification function to target tumor cell and a nucleic acid segment forming complementary sequence with the aptamer segment, and the aptamer segment and the nucleic acid segment are connected to form a hairpin type structure by a connection segment with the length of 7-15nm; and the capacity of the nucleic acid segment competitive hybridization aptamer segment is weaken than that of the target tumor cell. The application of the probe of the invention can be at least one of specificity detection of tumor living cell in buffer solution, effective detection on tumor living cell in serum and real-time imaging and vital diction of tumor in moving organism. The probe of the invention has higher stability, specificity and sensibility, application operation thereof is simple, fast, sensible and specific, and cost is low.

本发明属于核酸检测技术领域，具体公开了一种开关式核酸适体探针及其应用，该核酸适体探针包括探针本体和分别连接于该探针本体两端的荧光发生单元和荧光熄灭单元，探针本体包含有对目标肿瘤细胞具有特异性识别功能的核酸适体片段和与该核酸适体片段形成互补序列的核酸片段，核酸适体片段和核酸片段通过一7～15nm长的连接片段连接形成一发夹型结构；核酸片段竞争性杂交核酸适体片段的能力弱于目标肿瘤细胞。本发明探针的应用可以是对缓冲液中肿瘤活细胞的特异性检测、对血清中肿瘤活细胞的有效检测及活动物体内肿瘤的实时荧光成像和活体检测中的至少一种。本发明的探针具有较高稳定性、特异性和灵敏性，其应用操作简单、快速、灵敏、特异、成本低。