Triple Signal Amplification Strategy for Ultrasensitive Determination of miRNA Based on Duplex Specific Nuclease and Bridge DNA–Gold Nanoparticles

Abnormal expression of miRNAs always occurs in solid tumors. Thus, it is critical to sensitively and selectively detect such biomarkers for the diagnosis and prognosis of diseases. Here, we report a biosensing scheme for the determination of miRNA with triple signal amplification based on target-triggered cyclic duplex specific nuclease digestion and bridge DNA–gold nanoparticles. Electrochemical signals are recorded to present initial levels of miRNA. This method is ultrasensitive with a wide linear range of 10–17 to 10–11 M. The limit of detection is down to 6.8 aM. Moreover, the overexpression of miR-21 is confirmed in lung cancer patients by the proposed method, which is in good accordance with qRT-PCR results. In addition, the developed biosensor does not need a reverse transcription process or any thermal cycling processes. Its performance satisfies the requirement for convenient, rapid, sensitive, and specific early diagnosis of cancers. Therefore, it may have great potential utility in the near future.