The structure thus has no dsDNA spacers as even the looped region was targeted by a TFO staple. two triplex turns and two, three, and four duplex turns, respectively, corresponding to total segment lengths of 60.7 nm (100 bt + 84 bp), 74.5 nm (100 bt + 126 bp), and 88.4 nm (100 bt + 168 bp) discounting loops. The incremental insertion of 42 additional base pairs (13.9 nm) per segment bends the bundle by roughly 180°. e, Horseshoe with eight TFO staples that recognize 16, 20, and 24 bt domains, respectively, separated by 7, 14, and 21 bp dsDNA spacers in the inner, middle, and outer folded segments. This corresponds to total segment lengths of 60.7 nm (128 bt + 49 bp), 85.1 nm (160 bt + 98 bp), and 111.9 nm (192 bt + 147 bp) discounting loops. The additional insertion of 32 bt and 49 bp (26.7 nm) per segment bends the bundle by roughly 300°. f, Tilde, similar to the horse-shoe, but the inner and outer segments switch midway through the bundle. AFM images for a-c and d-f scaled to 300 ´ 300 nm 2 and 150 ´ 150 nm 2 , respectively.