Sensitive analysis of miRNAs via primer exchange reaction integrated with hairpin catalytic reaction

MicroRNAs (miRNAs) can serve as potential biological targets for early screening, targeted therapy, and prognosis in ovarian cancer (OC). However, sensitive and reliable quantification and identification of miRNA remain a huge challenge. Herein, we proposed a simple and reliable approach for the ultra-sensitive detection of miRNA by integrating endonuclease-III (Exo-III) assisted signal recycle, primer exchange reaction (PER), and hairpin catalytic reaction (HCR). In this method, target miRNA specifically binds with toehold sequence to form a blunt 3’ terminus in the detection probe (dumbbell probe) that can be recognized by Exo-III, and to initiate subsequent signal amplifications. Based on this, the approach is successfully utilized in detecting OC related miRNAs with high sensitivity (limit of detection for miRNA-211 was 13 aM) and stability. By simply changing the toehold sequence in detection probe, the established approach can be easily extended to other miRNA detection. We believe that the platform is robust in detecting OS related biomarkers and is promising in renovating cancer diagnostic tools.