The three-way junction DNAzyme based probe for label-free colorimetric detection of DNA

► We report a label-free biosensor for the detection of target DNA. ► A DNAzyme-linked hairpin structure was designed as signal probe. ► The DNAzyme activity depends on the hairpin opening due to the three-way (target-hairpin-assistant) junction. ► This strategy exhibits high discrimination ability even against single-base mismatch.