A　novel　three-way　junction　DNAzyme　based　probe　has　been　designed　for　the　colorimetric　sensing　of　target　DNA.　Specifically,　a　DNAzyme-linked　hairpin　DNA　is　used　as　a　signal　probe.　In　the　presence　of　target　DNA,　the　signal　probe,　assistant　probe　and　target　DNA　can　hybridize　with　each　other,　resulting　in　the　formation　of　a　three-way　junction　DNA.　At　the　same　time,　the　signal　probe　is　opened　and　the　DNAzyme　sequence　in　the　signal　probe　is　dehybridized.　Subsequently,　in　the　presence　of　hemin,　the　DNAzyme　sequence　forms　a　G-quadruplex-hemin　complex,　which　catalyzes　oxidation　of　2,　2＇-azinobis　(3-ethylbenzthiazoline-6-sulfonic　acid)　(ABTS)　by　H2O2　to　the　colored　ABTS(center　dot-)　radical.　The　significant　color　changes　can　be　distinguished　visually.　By　the　combination　of　the　hairpin　probe　and　the　three-way　junction　DNA　probe,　the　proposed　sensor　exhibits　high　recognition　property　for　single-nucleotide　polymorphisms　(SNPs).　This　sensor　allows　the　detection　of　target　DNA　at　a　concentration　as　low　as　0.25　nmol　L-1.　The　proposed　sensor　is　easy　to　fabricate,　which　avoids　the　tedious　and　expensive　labeling　procedures,　and　exhibits　high　selectivity　against　single-base　mismatched　DNA.　(C)　2012　Elsevier　B.V.　All　rights　reserved.