A　novel　junction-probe　electrochemical　biosensor　for　the　sequence-specific　detection　of　DNA　with　higher　sensitivity　and　higher　discrimination　ability　was　described　in　here.　This　DNA　biosensor　is　based　on　＂junction-probe＂　detection　strategy,　which　operates　via　a　concept　called　template-enhanced　hybridization　processes　(TeHyP).　TeHyP　encompasses　a　design　strategy　whereby　two　probes　that　do　not　hybridize　to　each　other　at　a　specific　temperature　can　be　made　to　anneal　to　each　other　in　the　presence　of　a　template　(target)　via　the　formation　of　a　ternary　complex　(＂Y＂　junction　structure).　The　resulting　structure　that　forms　after　the　template-enhanced　hybridization　then　was　detected　by　electrochemical　method　with　[Ru(NH3)(6)](3+),　as　signal　molecule.　We　demonstrated　that　the　formation　of　＂Y＂　junction　structure　brings　more　[Ru(NH3)(6)](3+)　to　the　electrode　surface　via　electrostatic　interaction　and　results　in　an　increasing　electrochemical　signal.　The　increasing　electrochemical　signal　sensitively　reflects　the　concentration　of　target　DNA　and　shows　a　good　linear　relationship　with　the　concentration　of　target　DNA.　By　employing　above　strategy,　this　DNA　biosensor　could　detect　as　low　as　7.6　x　10(-13)　M　target　DNA　and　exhibited　high　discrimination　ability　even　against　single-base　mismatch.　In　addition,　this　novel　DNA　biosensor　is　easy　to　fabricate　and　convenient　to　operate,　and　shows　good　stability,　reproducibility　and　reusability.　(C)　2009　Elsevier　B.V.　All　rights　reserved.