Circulating　tumor　cells　(CTCs)　are　known　as　the　root　cause　of　cancer　metastasis　that　accounts　for　90%　of　cancer　death.　Owing　to　the　rarity　of　blood　CTCs　and　their　microenvironmental　complexity,　the　existing　biotechnology　could　not　precisely　capture　and　apoptosize　CTCs　in　vivo　for　cancer　metastasis　prevention.　Here,　we　designed　two　double　strand　circular　aptamers　aimed　to　simultaneously　target　MUC1　and　HER2　surface　biomarkers　on　mesenchymal　cancer　cells.　The　circular　aptamers　are　composed　of　a　capture　arm　for　binding　and　seizing　CTCs　and　a　circular　body　for　resisting　degradation　by　exonucleases.　We　conjugated　the　two　circular　aptamers　onto　dendrimer　PAMAM　G4.5　(dcAp1-G-dcAp2),　and　the　conjugate　entity　showed　both　significantly-enhanced　biostability　in　serum　for　days　compared　with　their　linear　counterparts　and　capture　specificity　in　RBC　(1:10　8　)　compared　with　their　single　circular　aptamers.　dcAp1-G-dcAp2　apoptosized　the　targeted　cells　and　inhibited　their　bioenergetic　activities　significantly　by　lowing　△Ψm,　ATP　and　lactate　productions　while　increasing　ROS　production.　dcAp1-G-dcAp2　captured　CTCs　in　mice　in　vivo　and　in　patient　blood.　This　study　lays　the　foundation　for　developing　multiple　biostable　circular　aptamers　and　conjugating　them　together　to　precisely　capture　and　apoptosize　mesenchymal　CTCs　in　vivo.　©　2018　Elsevier　B.V.