A　Tb3+-promoted　G-quadruplex-hemin　DNAzyme　was　first　reported　in　here.　We　demonstrated　that　trace　Tb3+　is　able　to　induce　guanine-rich　DNA　(5＇-TGGGTAGGGCGGGTTGGGAAA-3＇)　folding　into　a　compact　antiparallel　G-quadruplex　structure　and　thus　allows　the　formation　of　G-quadruplex-hemin　DNAzyme.　The　proposed　DNAzyme　can　effectively　catalyze　the　H2O2-mediated　oxidation　of　TMB　(3,3＇,5,5＇-tetramethylbenzidine　sulfate)　and　leads　to　a　change　from　colorless　to　blue　in　solution　color,　which　provides　a　sensing　platform　for　the　label-free　visual　detection　of　Tb3+.　Using　above　sensing　platform,　a　selective　and　sensitive　label-free　visual　method　for　the　detection　of　trace　Tb3+　was　developed.　The　proposed　method　can　be　used　to　detect　as　low　as　1.13　x　10(-7)　M　of　Tb3+　by　the　naked　eyes　observation　and　9.0　x　10(-9)　M　of　Tb3+　by　UV-vis　spectrophotometry　with　a　better　stability　and　reproducibility.　Compared　with　K+-promoted　G-quadruplex-hemin　DNAzyme　reported　in　previous　study,　the　novel　Tb3+-promoted　G-quadruplex-hemin　DNAzyme　has　much　higher　peroxidase　activity　and　better　specificity,　which　lead　to　a　great　potential　in　the　development　of　optical,　electrochemical　and　chemiluminescence　DNAzyme-based　biosensors.　(C)　2011　Elsevier　B.V.　All　rights　reserved.