Cocatalysis of catalytic hairpin assembly and ternary heterojunction BiS@MoS@BiMoO promotes ultra-sensitive electrochemical of detection MiRNA-21.

Ternary heterojunction BiS/MoS/BiMoO was designed as a signal probe to develop a dual signal amplification strategy empowered electrochemical biosensor for sensitive miRNA-21 detection by combining with catalytic hairpin assembly (CHA). The combination of the BiS/MoS/BiMoO heterojunction as a tracer indication probe and the CHA amplification strategy not only took fully use of the highly dense nanowire interwoven structure and superior active region of the probe, but also endowed the ability to improve the molecular hybridization efficiency by collision, which significantly avoided the cumbersome chain design and greatly simplified the step-by-step construction of the electrode surface. Hairpin H1 was first added dropwise to the gold nanoparticle-decorated electrode surface, and then opened by the introduced miRNA-21 to initiate the specific hybridization. Once the H2-MB/BiS/MoS/BiMoO heterojunction was added, more sensitive and rapid detection of miRNA-21 would be achieved through the introduction of methylene blue since the cocatalysis of hairpin assembly and ternary heterojunction BiS@MoS@BiMoO. Finally, the constructed biosensor demonstrated effective performance in the detection of miRNA-21 within the linear range of 1 fM to 100 pM with a detection limit of 0.31 fM. The satisfactory analysis of human blood samples further validated the preferable reliability and practicability of this new strategy for the ultrasensitive detection of miRNA.