Unmarked fluorescence sensor and preparation method and application thereof

The invention belongs to the field of biological detection, and relates to an unmarked fluorescence sensor, in particular to an unmarked fluorescence sensor as well as a preparation method and application thereof. According to the application, different non-G basic groups are added at the tail end, multiple molecular hairpins containing G-rich sequences are designed, and the molecular hairpins are combined with ThT to construct a marker A beta DNA for detecting the Alzheimer's syndrome based on a G-triplex (signal descending type) and G-quadruplex (signal ascending type) unmarked fluorescence sensor. Compared with the preparation and detection results of the two sensors, the sensor based on the G-triplex can be prepared by only needing a small amount of G-C base pairs, K < + > and ThT, the preparation cost is low, but the output signal intensity is weak, the detection limit is high, and low-concentration target DNA detection is not facilitated; the preparation cost of the sensor based on ...