DNAzyme assisted self-feedback electrochemiluminescence signal amplification for the detection of miRNA-622

A novel microRNA (miRNA-622) biosensor platform was constructed based on nano-confined effect of vertically-ordered mesoporous silica film (VMSF) and self-feedback cascade amplification strategy of DNAzyme. VMSF was grown in-situ on the ITO electrode surface, which could effectively block the interference of biological matrix and enrich the luminophore by its nano-confinement effect. Meanwhile, DNAzyme walking strands and ferrocene-labeled substrate strands were immobilized on the electrode surface through Au-S bonds, quenched the ECL signal and switched the signal-off. Upon the addition of target miRNA-622, the DNAzyme walker was activated and moved autonomously, completing substrate strand cleavage and signal-on with the assistance of Mg²⁺. The released substrate strands could act as target analogues to reactivate DNAzyme, realizing self-feedback cascade amplification. By organically combining the anti-interference performance of nanomaterials with the signal amplification capacity of DNAzyme, the constructed sensing platform achieved high-sensitivity quantitative detection of miRNA-622 with a linear range spanning from 1 fM to 10 nM and a detection limit as low as 0.65 fM. This study provided a promising approach for the precise determination of low-abundance miRNAs.