Fig. 2: Self-assembly of TC-RNA tiles to ladders.

a The design schematic showcases five TC-RNA tiles alongside their corresponding assembled ladders. Colored region indicates complementary sticky end pairing. Each complementary sticky-end-sticky-end pair or sticky-end-T-loop pair is labeled with the same color. The red circles highlight the locations of crossovers. The blue circles label the locations of crossovers. b AFM images of assembled arrays. From left to right, the arrays are assembled from tile TC-RNA-5, tile TC-RNA-6, tile TC-RNA-7, tile TC-RNA-8, and tile TC-RNA-9, respectively. All the AFM images are taken after annealing in 1×TAE Mg²⁺ buffer from 70 °C to 15 °C for 12 h. The scale bar is 100 nm for all images. c Cryo-EM and tomography reconstruction images of TC-RNA-8. Left, slice through a tomogram of TC-RNA-8; right, 3D segmentation of that tomogram with individual particles visualized in insets. d The design schematic and AFM images of single-stranded TC-RNA-10 tile. The AFM images of cotranscriptional folding in solution and on mica are taken after annealing in 1×TAE Mg²⁺ buffer at 37 °C for 1 h. The AFM images of thermos-annealing in solution and on mica are taken after annealing in 1×TAE Mg²⁺ buffer from 70 °C to 15 °C for 12 h. All AFM images in this figure were reproduced at least three times, with each experiment conducted independently. The scale bar is 100 nm for all images.