Using　an　external　redox-active　molecule　as　a　DNA　hybridization　indicator　is　still　a　popular　strategy　in　electrochemical　DNA　biosensors　because　it　is　label-free　and　the　multi-site　binding　can　enhance　the　response　signal.　A　planar　and　uncharged　transition　metal　complex,　Cu(PA)2　(PA　=　picolinic　acid)　with　excellent　electrochemical　activity　has　been　synthesized　and　its　interaction　with　double-stranded　DNA　(dsDNA)　is　studied　by　experimental　electrochemical　methods　and　theoretical　molecular　docking　technology.　The　experimental　results　reveal　that　the　copper　complex　interacts　with　dsDNA　via　specific　intercalation,　which　is　verified　by　the　molecular　docking　result.　The　surface-based　voltammetric　analysis　demonstrates　that　the　planar　Cu(PA)2　can　effectively　accumulate　within　the　electrode-confined　hybridized　duplex　DNA　rather　than　the　single-stranded　probe　DNA.　Based　on　this　phenomenon,　the　Cu(PA)2　is　utilized　as　an　electrochemical　hybridization　indicator　for　the　detection　of　oligonucleotides.　The　sensing　assays　show　that　upon　incubation　in　Cu(PA)2　solution,　the　probe　electrode　does　not　display　any　Faraday　signal,　but　the　hybridized　one　has　a　pair　of　strong　redox　peaks　corresponding　to　the　electrochemistry　of　Cu(PA)2,　showing　excellent　hybridization　indicating　function　of　Cu(PA)2　without　background　interference.　The　signal　intensity　of　Cu(PA)2　is　dependent　on　the　concentrations　of　the　target　oligonucleotide　ranging　from　1　fM　to　100　nM　with　an　experimental　detection　limit　of　1.0　fM.　Due　to　the　specific　intercalation　of　Cu(PA)2　with　dsDNA,　the　biosensor　also　exhibits　good　ability　to　recognize　oligonucleotide　with　different　base　mismatching　degree.　©　2019