Entropy-driven spliced DNA walking machine for label-free electrochemical detection of antibiotics

Abstract

Herein, we have integrated an entropy-driven DNA walking machine into electrochemical platform for label-free sensing of antibiotics. As far as we know, this work is the first time that entropy-driven DNA machine has been used for antibiotics detection. The designed DNA machine is activated by a target-triggered catalytic hairpin assembly to form a spliced DNA walker long-arm. Then the autonomous and progressive spliced walk long-arm on electrode surface via the toehold-mediated strand displacement reaction induces continuous release of signal probe (SP) from three-stranded DNA complex. The freedom of SP leads to the generation of abundant G-quadruplex DNAzyme which can catalyze decomposition of hydrogen peroxide, so an extremely intense electrochemical response is observed. Our spliced DNA walking machine precedes the previous DNA machine in terms of economy and stability due to the strategy of entropy-driven and label-free, and possesses a detection limit to 0.96 pM for detection of ampicillin. Moreover, this DNA machine is expected to detect more analytes by using corresponding aptamer probes. Hence, the entropy-driven DNA walker provides an efficient and practical platform for small molecule analysis.