Figure 1.

pH-controlled self-assembly of DNA tiles. We have achieved pH-controlled DNA tile assembly by coupling an upstream re-engineered pH-controlled circuit with a downstream DNA tile self-assembly process. (1) In the pH-dependent upstream circuit, a catalyst (C) binds to a pH-dependent substrate, leading to the release of a deprotector strand (D). (2) The D strand, in turn, activates a downstream self-assembly reaction by irreversibly associating with a protected tile (PT). This leads to reactive double-crossover tiles (RT) self-assembling into lattices and nanotubes (right). The pH-dependent substrate is implemented with a clamp-like triplex-forming DNA strand (T) that, under acidic pHs, can form a triplex complex, inhibiting the strand displacement reaction with the catalyst.