• A novel method for biosensor fabrication based on target recycling and polymerization signal amplification strategies
  • Aria Raoufi,1,*
    1. Dr. Mohammad Shafiee’s High School


  • Introduction: The detection of microRNAs (miRs) with the specific sequence is an important factor in the disease’s diagnosis. In this study, a double signal amplification electrochemical biosensor for sensitive detection of miRNA-21 based on a duplex-specific nuclease (DSN)-assisted target recycling was developed which combined with electrochemically mediated surface-initiated ATRP (eATRP) signal amplification.
  • Methods: In the absence of target miRNA, hairpin DNAs (hDNAs) provide a high density of phosphate groups for the subsequent attachment of eATRP initiators onto the electrode surface utilizing the phosphate-Zr4+-carboxylate chemistry, followed by the de novo growth of electroactive polymer via the SI-eATRP. De novo growth of long polymeric chains enables the labeling of numerous electroactive probes, which produce a highly electrochemical response.
  • Results: In the presence of target miRNA, the hDNA on the electrode surface hybridizes with target miRNA (T-miR) and forms RNA/DNA duplexes, which become the substrate of the DSN. As DSN cleaves only the DNA strands in the duplexes, the target miRNA is released and then hybridized with another hDNA.
  • Conclusion: Finally, in this “signal off” method, the electrochemical signal reduced in the presence of T-miR because of the elimination of a large amount of hDNA by one miRNA. Furthermore, this method can distinguish similar miRNAs that differ by only one base due to the strong differentiating ability of DSN. Ultimately, the proposed biosensor has great potential to provide a platform for the sensitive and selective detection of miRNAs.
  • Keywords: Electrochemical biosensor, MicroRNAs, Duplex specific nuclease