Reagents

MTT and calcein were purchased from Sigma-Aldrich (USA). Phi29 DNA polymerase, T4 DNA ligase, exonuclease I, exonuclease III and dNTPs were purchased from New England Biolabs Ltd. Annexin V-FITC apoptosis detection kit was purchased from BD Biosciences (USA). Anti-VEGF primary antibody (19003-1-AP) was purchased from Proteintech Group (USA) and 50 times diluted during experiments. FITC-conjugated secondary antibody (111-095-003) was purchased from Jackson ImmunoResearch (USA) and 100 times diluted during experiments. LysoTracker Green and DAPI were purchased from Invitrogen (Carlsbad, CA, USA). SYBR Green I was obtained from Generay Biotech Co., Ltd (China). PBS (pH 7.4) contained 136.7 mM NaCl, 2.7 mM KCl, 8.72 mM Na₂HPO₄ and 1.41 mM KH₂PO₄. The reaction buffer was prepared using the PBS containing 0.5 mM MgCl₂ and 50 μM ZnCl₂, which helped the efficient binding between aptamers and receptors, as well as providing MNAzyme with Zn²⁺ for autocatalytical cleavage of hairpin structure from the ONV. TAMg buffer (1 × ) was composed of 45 mM Tris and 7.6 mM MgCl₂, with pH adjusted to 8.0 using glacial acetic acid. All other reagents were of analytical grade. All aqueous solutions were prepared using ultrapure water (≥18 MΩ, Milli-Q, Millipore). siRNAs were obtained from GenePharma Co. Ltd (Shanghai, China). The siRNA sequences were as follows: VEGF siRNA, Cy3-sense 5′-Cy3-GGAGUACCCUGAUGAGAUCdTdT-3′, Cy5-sense 5′-Cy5-GGAGUACCCUGAUGAGAUCdTdT-3′, antisense 5′-GAUCUCAUCAGGGUACUCCdTdTCAAAUGGACCAAGGCCAG-3′, 21 base antisense 5′-GAUCUCAUCAGGGUACUCCdTdT-3′; second active VEGF siRNA, sense 5′-ACCUCACCAAGGCCAGCACdTdT-3′, antisense 5′-GUGCUGGCCUUGGUGAGGUdTdTCAAAUGGACCAAGGCCAG-3′; negative control siRNA, sense 5′-UUCUCCGAACGUGUCACGUdTdT-3′ and antisense 5′-ACGUGACACGUUCGGAGAAdTdTCAAAUGGACCAAGGCCA G-3′. All of the DNA were synthesized and purified by Sangon Biotech Co., Ltd (Shanghai, China). Their sequences were listed in Supplementary Table 1.