Signal-on electrochemical detection of antibiotics based on exonuclease III-assisted autocatalytic DNA biosensing platform

In this work, a novel electrochemical DNA sensor based on exonuclease III (Exo III)-assisted autocatalytic DNA biosensing platform for ultrasensitive detection of antibiotics has been reported. When the arched probe was challenged with target, the released primer caused by the specific recognition of the aptamer and target antibiotics hybridized with the 3'-protruding terminus in the HP1. Then, Exo III could catalyze the stepwise removal of mononucleotides from this flat terminus, resulting in the release of the primer and trigger. As a secondary target, trigger could replace Helper from the 5'-MB labeled HP2, and HP2 formed a "close" probe structure, confining MB close to the electrode surface for efficient electron transfer. To our best knowledge, such work is the first report about Exo III-assisted autocatalytic DNA biosensing platform combing with signal-on sensing strategy, which has been utilized for quantitative determination of antibiotics. It would be further used as a general strategy associated with more analytical techniques toward the detection of a wide spectrum of analytes. Thus, it holds great potential for the development of ultrasensitive biosensing platform for the applications in bioanalysis, disease diagnostics, and clinical biomedicine.