This　works　reports　a　new　signal-on　amplification　strategy　for　sensitive　electronic　detection　of　nucleic　acid　based　on　the　isothermal　circular　strand-displacement　polymerization　(ICSDP)　reaction.　The　assay　mainly　involves　a　hybridization　of　ferrocene-labeled　hairpin　DNA　with　blocker　DNA,　a　strand-displacement　process　with　target　DNA,　and　an　ICSDP-based　polymerization　reaction.　The　signal　is　amplified　by　the　labeled　ferrocene　on　the　hairpin　probe　with　target　recycling.　Upon　addition　of　target　analyte,　the　blocker　DNA　is　initially　displaced　by　target　DNA　from　the　hairpin/blocker　DNA　duplex　owing　to　the　difference　of　the　folding　free　energy,　then　the　newly　formed　target/blocker　DNA　duplex　causes　the　ICSDP　reaction　with　the　aid　of　the　primer　and　polymerase,　and　then　the　released　target　DNA　retriggers　the　strand-displacement　for　target　recycling.　Numerous　ferrocene　molecules　are　close　to　the　electrode　surface　due　to　the　reformation　of　hairpin　DNA,　each　of　which　produces　an　electronic　signal　within　the　applied　potentials,　thereby　resulting　in　the　amplification　of　electrochemical　signal.　Under　the　optimal　conditions,　the　ICSDP-based　amplification　method　displays　good　electrochemical　responses　for　detection　of　target　DNA　at　a　concentration　as　low　as　0.03　pM.　(C)　2013　Elsevier　B.V.　All　rights　reserved.