Wedged DNA Walker Coupled with a Bimetallic Metal–Organic Framework Electrocatalyst for Rapid and Sensitive Monitoring of DNA Methylation

The dissociation of the walking strand from the track gives rise to decreased efficiency and long reaction time of DNA walkers. In this work, we constructed a DNA walker combining the introduction of a wedge segment with a bimetallic metal–organic framework (MOF) electrocatalyst to solve this problem. The target methylated DNA acted as a single-legged walker, and the immobilization probe assembled on the track contained a wedge segment that was complementary to the target methylated DNA persistently, inhibiting its dissociation from the track. The fuel strand modified with a bimetallic MOF would drive the target strand to conduct branch migration and move processively along the track. The stepwise movement of the target strand resulted in the loading of numerous bimetallic MOF catalysts to reduce H2O2 at the electrode interface, thereby a significantly increased current response would be obtained for the detection of methylated DNA. This DNA walker achieved a detection limit of 200 aM within 20 min and effectively distinguished DNA with different methylation statuses, which would pave a way for rapid and sensitive monitoring of DNA methylation.