DNA-based shape-memory hydrogels revealing switchable shape recovery in the presence of two orthogonal triggers are described. In one system, a shaped DNA/acrylamide hydrogel is stabilized by duplex nucleic acids and pH-responsive cytosine-rich, i-motif, bridges. Separation of the i-motif bridges at pH 7.4 transforms the hydrogel into a quasi-liquid, shapeless state, that includes the duplex bridges as permanent shape-memory elements. Subjecting the quasi-liquid state to pH 5.0 or Ag(+) ions recovers the hydrogel shape, due to the stabilization of the hydrogel by i-motif or C-Ag(+) -C bridged i-motif. The cysteamine-induced transformation of the duplex/C-Ag(+) -C bridged i-motif hydrogel into a quasi-liquid shapeless state results in the recovery of the shaped hydrogel in the presence of H(+) or Ag(+) ions as triggers. In a second system, a shaped DNA/acrylamide hydrogel is generated by DNA duplexes and bridging Pb(2+) or Sr(2+) ions-stabilized G-quadruplex subunits. Subjecting the shaped hydrogel to the DOTA or KP ligands eliminates the Pb(2+) or Sr(2+) ions from the respective hydrogels, leading to shapeless, memory-containing, quasi-liquid states that restore the original shapes with Pb(2+) or Sr(2+) ions.
Aptamer‐capped, drug‐loaded metal‐organic framework nanoparticles (NOMFs) are synthesized by a click chemistry method by Itamar Willner and co‐workers in article number https://doi.org/10.1002/adfm.201702102. The NOMFs are unlocked by ATP, which is overexpressed in cancer cells, leading to high cytotoxic efficacy and targeted drug release to MDA‐MB‐231 breast cancer cells.
A novel micro in-pipe robot using an internally threaded profile for propulsion is proposed in this paper, and the dynamic model of the robot in the turbulent liquid pipeline is established, and the computational fluid dynamics method is used to solve the influence of environmental parameters and operating parameters on the robotic performance. By the orthogonal experimental optimization method, the optimal inner spiral structural parametrical combination is obtained. According to the working principle of the inner spiral robot, an inner spiral driving device is designed and fabricated, and the running experiment in the pipeline full of 201 methyl silicone oil verifies the feasibility of the proposed robot. Adopting the pulsating blood flow function as the inlet condition, in a pulsating period, the robotic performance is numerically analyzed.
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