A reagentless triplex DNA junctions-based electrochemical DNA sensor using signal amplification strategy of CHA and tetraferrocene

In this paper, we first synthesized a novel tetraferrocene signal marker. Then a reagentless triplex DNA junctions based electrochemical DNA sensor using signal amplification strategy of CHA and tetraferrocene was constructed. Tetraferrocene labeled hairpin probes (H1 and H2) were integrated together to form triplex DNA junctions through connecting chain (C1). It enabled catalytic hairpin assembly (CHA) reaction to be initiated without the addition of exogenous probe during the detection process, and the conformational change of the target caused the change of electrochemical signal. Combined with tetraferrocene and CHA strategies, the sensor achieved double signal amplification with a detection limit as low as 0.085pM. In addition, the sensor was successfully applied to mRNA detection in cells with high sensitivity and reagentless operation, providing possibilities for in vivo testing.