Catalytic-assembly of programmable atom equivalents.

Escape from metastable states in self-assembly of colloids is an intractable problem. Unlike the commonly adopted approach of thermal annealing, the recently developed enthalpy-mediated strategy provided a different option to address this dilemma in a dynamically controllable manner at room temperature. However, it required a complex catalytic-assembly DNA strand-displacement circuitry to mediate interaction between multiple components. In this work, we present a simple but effective way to achieve catalytic-assembly of DNA-functionalized colloidal nanoparticles, i.e., programmable atom equivalents, in a far-from-equilibrium system. A removable molecule named "catassembler" that acts as a catalyst was employed to rectify imperfect linkages and help the system escape from metastability without affecting the assembled framework. Notably, catalytic efficiency of the catassembler can be effectively improved by changing the seesaw catassembler in toehold length design or numbers of the repeat units. Leveraging this tractable catalytic-assembly approach, different ordered architectures were easily produced by directly mixing all reactants, as in chemical reactions. By switching bonding identities, solid-solid phase transformations between different colloidal crystals were achieved. This work opens up an avenue for programming colloid assembly in a far-from-equilibrium system.