Cascade-amplified fluorescence polarization assay for miRNA based on aggregation strategy of Y-shaped DNA

MicroRNAs (miRNAs) have emerged as one of the promising biomarkers. Their aberrant levels are intimately connected to various diseases. However, Sensitive assay of low-abundance miRNAs remain a grand challenge. Herein, a novel sensitive cascade-amplified fluorescence polarization (FP) sensing platform for miRNA detection was developed based on aggregation strategy of Y-shaped DNA via streptavidin (SA). The miRNA-155 was employed as the model target analyte. In the presence of miRNA-155, the duplex-specific nuclease (DSN) cycling amplification and catalytic hairpin assembly (CHA) cycling amplification were triggered successively. Owing to the target-triggering dual cyclic amplification, numerous Y-shaped DNA nanostructure could be easily generated according to the assembly order of hairpin probes. Then, SA was added to the system, inducing the aggregation of Y-shaped DNA nanostructure to form a large-size of DNA/SA complexes. Taking advantages of cascade-amplified strategy, a significant enhancement of the FP signal was achieved and a sensitive assay for miRNA detection was realized with the detection limit of 1 × 10-13 M. Beyond that, the proposed method could distinguish single-base mismatch and achieved satisfactory result for the expression level assay of miRNA-155 in different cell lines, holding great potential in the applications in miRNA-related clinical diagnosis and biochemical researches.