Target-triggered hybridization chain reaction for ultrasensitive dual-signal miRNA detection.

A signal amplification sensing system with target-triggered DNA cascade reaction combined with dual-signal readout technology was designed for ultrasensitive analysis of miRNA. The highly conductive metal organic frameworks (MOFs) derivative, N-doped carbon dodecahedron (N-PCD) was deposited with gold nanoparticles as the electrode substrate, which could assist the electron transfer between the molecular probe and the electrode surface, and could remarkably enhance electrochemical response. Tetrahedral DNA nanostructure (T4-DNA) with high structural stability and mechanical stiffness was designed to improve the loading capacity and binding efficiency of the target, thus increasing the sensitivity of the system. The non-enzymatic amplification method based on the DNA cascade reaction allows the electrochemical responses from dual signal DNA probes labeled with ferrocene (Fc) and methylene blue (MB), respectively in turn to improve the reliability of detection. Under optimal conditions, the sensor has a linear range of 5-1.0 × 104 fM, and the limit of detection is as low as 1.92 fM and 3.74 fM for Fc and MB labeled probe, respectively. This strategy raises the promising application for the rapid detection of miRNA targets with low abundance in complex biological systems.