An electrochemical aptasensor based on intelligent walking DNA nanomachine with cascade signal amplification powered by nuclease for Mucin 1 assay.

Intelligently walking DNA nanomachines have sprung up an upsurge in various nucleic acid testing, but the rapid and sensitive test methods toward disease biomarker proteins based on the signal amplification strategy of DNA nanomachines were still ongoing development. In this work, an electrochemical aptasensor coupling the magnetic separation technique with the nuclease-powered walking DNA nanomachine was established for Mucin 1 (MUC1) detection. The magnetic beads (MBs) were modified by MUC1 aptamer hybridized with blocker DNA probe (BDP). After reacting with MUC1 proteins, the BDP was released from MBs to trigger the opening of capture hairpin DNA on Au nanoparticle (Au NPs)/MXene-modified electrode surface. In the presence of exonuclease III (Exo III), the BDP as a DNA walker is activated to autonomously move on the electrode. Then, lots of residual DNA fragments can still stay on electrode, further hybridizing with hairpin DNA, which can capture more UiO-66-NH metal-organic frameworks (MOFs). The amounts of ligands in MOFs can generate enhanced differential pulse voltammetry (DPV) signal probes. Furthermore, the concentrations of MUC1 can convert into the amplified DPV signals by introducing the signal amplification between the BDP as DNA walkers and Exo III as driven forces. This proposed electrochemical aptasensor achieved MUC1 detection ranging from 5 pg/mL to 50 ng/mL with detection limit of 0.72 pg/mL. Consequently, the designed and nuclease-powered walking DNA nanomachine provided an efficient strategy for the quantitative analysis of proteins by the interconversion between protein and BDP as a walker, which exhibited practical applicability of MUC1 detection in human serum.