The sequence-patterned scaffolds impose some restrictions on the design freedom, whereas a continuous polypurine polyR scaffold allows for binding of TFO staples at any position. While more challenging, it is also possible to produce artificial genes composed entirely of purines in one strand. Specifically, two polyR deBruijn sequences of 854 bp and 3135 bp were synthesized and cloned into plasmids (Supplementary Table ). A single-fold structure with triplex formation at all positions self-assembled with near-perfect (>90%) yield from seventeen TFO staples and the polyR-854bp scaffold (Fig. ). The staples contain two nHS 24 nt recognition domains, thereby separating single crossovers with two triplex turns, and bind the scaffold contiguously along a 408 bt structure length (136 ± 17 nm).