Hairpin allosteric molecular beacons-based cascaded amplification for effective detection of lung cancer-associated microRNA.

Lung cancer with worldwide distribution, high incidence and low survival rate is significantly and increasingly threatening human health. Thus, the specific detection of lung cancer-associated biomarkers is of crucial importance in early diagnosis and treatment. In this work, taking microRNA-21 as an example, a biosensor is proposed via a stimuli-induced strand displacement amplification (SDA) and cascade signal amplification with the assistance of polymerase. An allosteric molecular beacon (MB) with chemical modification is designed to emit the enhanced fluorescent signal in presence of microRNA target. The sensing system possesses a linear calibration curve from 5 pM to 40 nM with the limit of detection (LOD) of 0.7 pM and displays good specificity to discriminate coexisting microRNAs. In addition, the feasibility is confirmed by performing the detection of miRNA-21 extracted from non-small cell lung cancer (NSCLC) A549 cells, and a good recovery is achieved in complex human serum sample. Therefore, the miRNA-triggered cascaded amplification would be crucial strategy to facilitate microRNA analysis in the biological detection and broad clinical applications.