A track-regenerated DNA walker: Construction and its derived sensing application

Herein, a track-regenerated DNA walker is constructed and applied for sensitive detection. Blocker-silenced walking strands and linear DNAs serving as roadbed strands are co-modified onto gold nanoparticles. Fluorophore/quencher dually-labeled hairpin DNAs serving as rail strands are free in solution. Roadbed strands hybridize with rail strands to form the track. Activated by the stimulus specifically binding to blocker, the walking strand will be liberated and hybridize with the rail strand to convert its 3′-end from protruding to recessed state. The rail strand then gets digested by exonuclease III, accompanying by fluorophore release and fluorescence enhancement. The vacant roadbed strand anew binds free rail strands, resulting in the regeneration of track. The walking strand continues to interact with the next rail strand and constantly steps forward on the regenerative track, accumulating large amounts of signal. This feature allows the DNA walker to be tailored into a sensor. For Ebola virus detection, it obtains a detection limit down to 3.5 fM and detects the target in biological fluids with good recovery. The DNA walker offers a new mode of sustainable operation and will provide a sensitively and reliably analytical tool in diagnosis.