Amperometric detection of microRNA based on DNA-controlled current of a molybdophosphate redox probe and amplification via hybridization chain reaction.

An electrochemical sensor is described for the determination of microRNA-21 by combing the DNA generated current with target-triggered hybridization chain reaction (HCR). A thiol-modified hairpin capture probe was first immobilized on a gold electrode. In the presence of microRNA-21, hybridization leads to a conformational change of the capture probe. The conformational change triggers HCR to generate a long DNA strand on the surface of the electrode. The phosphate backbone of the long DNA strand then reacts with molybdate to form the redox redox probe molybdophosphate, and this generates an electrochemical current. The HCR triggered by microRNA increases the amount of phosphate groups due to the extension of the DNA length, and thus increases the response current. The electrode, best operated at a voltage of 0.20 V, was successfully applied to the analysis of microRNA-21 in (spiked) human serum samples. In our perception, it represents a promising tool for analyzing a variety of microRNA biomarkers. Graphical abstract Electrochemical sensor for detection of microRNA-21 by combing the DNA generated electrochemical current concept with target-triggered hybridization chain reaction (HCR) strategy is reported. DNA strands (S1 and S2) were assembled onto electrode through HCR reaction. MCH: 6-mercapto-1-hexanol.