In　the　present　study,　we　proposed　a　novel　dual-cyclical　nucleic　acid　strand-displacement　polymerization　(dual-CNDP)　based　signal　amplification　system　for　highly　sensitive　determination　of　tumor　suppressor　genes.　The　system　primarily　consisted　of　a　signaling　hairpin　probe　(SHP),　a　label-free　hairpin　probe　(LHP)　and　an　initiating　primer　(IP).　The　presence　of　target　DNA　was　able　to　induce　one　CNDP　through　continuous　process　of　ligation,　polymerization　and　nicking,　leading　to　extensively　accumulation　of　two　nicked　triggers　(NT1　and　NT2).　Intriguingly,　the　NT1　could　directly　hybridize　SHP,　while　the　NT2　could　act　as　the　target　analog　to　induce　another　CNDP.　The　resulting　dual-CNDP　contributed　the　striking　signal　amplification,　and　only　a　very　weak　blank　noise　existed　since　the　ligation　template　of　target　was　not　involved.　In　this　case,　the　target　could　be　detected　in　a　wide　linear　range　(5　orders　of　magnitude),　and　a　low　detection　limit　(78　fM)　was　obtained,　which　is　superior　to　most　of　the　existing　fluorescent　methods.　Moreover,　the　dual-CNDP　sensing　system　provided　a　high　selectivity　towards　target　DNA　against　mismatched　target　and　was　successfully　applied　to　analysis　of　target　gene　extracted　from　cancer　cells　or　in　human　serum-contained　samples,　indicating　its　great　potential　for　practical　applications.　©　2016　Elsevier　B.V.