The sensor platform combined with dual signal amplification and based on UCNPs and CRISPR/Cas12a for MiRNA-21 detection

Cancer has become the research target of researchers because of its serious threat to human life and health. MicroRNA levels can change as cancer progresses and become a biomarker for cancer detection. In this work, a novel sensor system was designed for the detection of miRNA-21 which utilizes the luminescence properties of upconverted nanoparticles (UCNPs) and the trans-cleavage of CRISPR/Cas12a, and also introduces a dual signal amplification mediated by Exonuclease III (Exo III) and phi29 DNA polymerase. The improved hairpin probe (HP) can not only be opened by the UCNPs photocontrollably, but also guide the target to cycle under the Exo III cut, achieving the first amplification of the signal. Subsequently, rolling circle amplification (RCA) realizes the signal secondary amplification. A large number of repeated sequences, which binds to Cas12a/crRNA and activates the trans-cutting activity of Cas12a, are generated in the process of RCA. Finally, the fluorescence signal can be recovered and highly sensitive detection for targets can be realized. The construction of one-to-many technology between target and signal is realized due to the dual signal amplification and the detection limit is 6.01 fM. In addition, the sensor system also has shown excellent performance in serum and cell lysates.