Fig. 1. Scheme of the crystallization of DNA origami building blocks at room temperature. (a) Model of the binary regular-octahedral DNA origami building blocks. (b) The vertex-to-vertex binding mode between the adjacent building blocks. (c) Structure properties of the assemblies with strong, moderate, and weak binding strengths, respectively. (d) In conventional assembly, heat treatment (HT) drives the formation of ordered assemblies from DNA origami building blocks, while crystallization at room temperature (RT) leads to amorphous aggregates. (e) In this study, urea-mediated crystallization can form ordered assemblies within 4 hours, which further grow into cubic microcrystals with considerable size within 2 days.