G-Quadruplex-Mediated Molecular Switching of Self-Assembled 3D DNA Nanocages

We demonstrated a strategy to reversibly extend and contract 3D DNA nanocages based on G-rich DNA strands as scaffolds in the presence of K⁺ or chelating agents. The contraction and extension of nanocage would be regulated by formation and deformation of G-quadruplex in the presence of K⁺ ions and chelating agents, respectively. Compared to single telomeric DNA strands, self-assembled 3D DNA nanocages integrated with three HTLs act as horseradish peroxidase mimicking DNAzymes for colorimetric detection and monitoring of cholesterol with high stability toward nuclease and blood serum degradations. This is the first example of facile construction of 3D DNA nanostructures with contractile, reversible, and catalytic features based on the assembly and disassembly of G-quadruplexes. This work offers a new platform for manipulation of nanoscale conformational changes and a step forward in obtaining stimuli-responsive 3D DNA nanomaterials with versatile reactivity and functionalities.