A　new　signal　amplification　strategy　based　on　target-regulated　DNA　proximity　hybridization　(TRPH)　reaction　accompanying　formation　of　three-way　DNA　junction　was　designed　for　electronic　detection　of　Microcystin-LR　(MC-LR　used　in　this　case),　coupling　with　junction-induced　isothermal　cycling　signal　amplification.　Initially,　a　sandwiched-type　immunoreaction　was　carried　out　in　a　low-cost　PCR　tube　between　anti-MC-LR　mAb1　antibody-labeled　DNA1　(mAb1-DNA1)　and　anti-MC-LR　mAb2-labeled　DNA2　(mAb2-DNA2)　in　the　presence　of　target　to　form　a　three-way　DNA　junction.　Then,　the　junction　could　undergo　an　unbiased　strand　displacement　reaction　on　an　h-like　DNA　nanostructure-modified　electrode　(labeled　with　methylene　blue　redox　tag　on　the　short　DNA　strand),　thereby　resulting　in　the　dissociation　of　methylene　blue-labeled　signal　DNA　from　the　electrode.　The　newly　formed　double-stranded　DNA　could　be　cleaved　again　by　exonuclease　III,　and　the　released　three-way　DNA　junction　retriggered　the　strand-displacement　reaction　with　h-like　DNA　nanostructures　for　junction　recycling.　During　the　strand-displacement　reaction,　numerous　methylene　blue-labeled　DNA　strands　were　far　away　from　the　electrode,　thus　decreasing　the　detectable　electrochemical　signal　within　the　applied　potentials.　Under　optimal　conditions,　the　TRPH-based　immunosensing　system　exhibited　good　electrochemical　responses　for　detecting　target　MC-LR　at　a　concentration　as　low　as　1.0ngkg-1　(1.0ppt).　Additionally,　the　precision,　reproducibility,　©　2015　Elsevier　B.V.