Magnetic Assisted DNA Logic Gate Nanomachine Based on CRISPR/Cas12a for Recognition of Dual miRNAs

The anomalous expression of microRNA poses a serious threat to human life and health safety, and serves as an important biomarker for cancer detection. In this study, a novel magnetic-assisted DNA logic gate nanomachine triggered by miRNA-21 and miRNA-155 was designed based on the trans-cleavage activity of CRISPR/Cas12a activated by a split DNA activator, using only a single crRNA and signal probe, which simplified the detection procedure and complex nucleic acid amplification. The presence of target molecules, miRNA-21 and miRNA-155, can stimulate the DNA walker machine assembled on magnetic beads, which releases activator under the action of DNAzyme. Then the trans-cleavage activity of CRISPR/Cas12a is initiated and the system signal significantly increases. Based on this, an AND logic gate nanomachine was constructed for simultaneous analysis of miRNA-21 and miRNA-155. The detection limits of miRNA-21 and miRNA-15 were 9.00 pM and 42.00 pM, respectively, and this method was successfully applied to miRNA analysis in cell samples. This nanomachine combined the DNA walker with DNA logic circuit and CRISPR/Cas12a system, providing a new approach for simultaneous detection of multiple targets and further expanding the application of gene editing in the analysis and sensing of multiple target substances.