Fig. 3. Stability analyses of the Apt/Dz catenane and the linear Dz incubated with (A) 10% FBS, (B) exonuclease I (0.5 U L⁻¹) and (C) cell lysate of MCF-7 cells for different time frames by 6% native PAGE. (D) The catalytic activity assay of Apt/Dz: (a) S, (b) Apt/Dz incubated with buffer and (c) Apt/Dz incubated with cell lysate. Apt/Dz was incubated with cell lysate for 5 h, followed by being heated to 90 °C for 15 min and cooling down to 25 °C. TK1 mRNA and S were then added and incubated for 1.5 h at 37 °C before fluorescence measurement. The concentrations of S, Apt/Dz, TK1 mRNA and Mg²⁺ were 100 nM, 100 nM, 50 nM and 10 mM, respectively.