Electrochemical detection of microRNAs based on AuNPs/CNNS nanocomposite with Duplex-specific nuclease assisted target recycling to improve the sensitivity.

MicroRNAs (miRNAs) are important biomarkers in early diagnosis of disease. In this work, we developed a simple and effective electrochemical biosensor based on Au nanoparticles (AuNPs)/Carbon nitride nanosheet (CNNS) nanocomposite for the miRNAs detection. Duplex-specific nuclease (DSN) and hairpin structure probe were utilized to improve the sensitivity and selectivity respectively. In the presence of miRNA-21, the signal molecule could be released from the surface of the electrode and decrease the current peak in square wave voltammetry (SWV) test. Under the optimal conditions, the reported biosensor showed that the detection range of miRNA-21 is from 10 fM to 1 nM and detection limit is as low as 2.9 fM. Furthermore, the detection of miRNA-21 added in serum samples indicates the developed biosensor with good selectivity, stability and reproducibility which verify its potential to be used in the early diagnosis of diseases.