▎ 摘　　要

In this work, an electrochemical sensing platform, analogous to a DNA walker, was explored with exonuclease III (EXO III) as a driving force, tetraferrocene as a signal marker, and reduced graphene oxide (RGO) electrode as two-dimensional (2D) orbit to realize ultrasensitive detection of target DNA. We designed a single hairpin DNA probe with 3 '-end modified tetraferrocene, immobilized on the electrode surface by pi-pi stacking between the 5 ' terminus and reduced graphene oxide. In addition, EXO III digested the double-stranded DNA with a blunt 3 ' terminus formed by the target DNA and the probe DNA, thus degrading the 3 ' end of probe DNA, and resulting in the away movement of tetraferrocene from the electrode surface, decreasing the electrochemical signal. The proposed electrochemical sensor was very simple and stable with acceptable reproducibility, excellent DNA detection performance, and a detection limit as low as 0.3 pM.