DNA origami (Rothemund, 2006) does not use DNA for genetic information — it uses the predictable geometry of Watson-Crick base pairing as a structural material. A single very long "scaffold" strand (in real experiments, often the natural ~7,249-nucleotide circular genome of the M13 bacteriophage virus) starts randomly coiled, like a tangled thread. Hundreds of short synthetic "staple" strands (~20–40 nucleotides each) are added; each staple is designed so its two halves are complementary to two widely separated regions of the scaffold. When a staple binds, it pulls those two distant scaffold regions together and locks them side by side — "stapling" the thread back on itself. Applied across hundreds of staples in a designed order, this repeated stapling forces the once-shapeless scaffold to crease and fold into a predetermined 2D or 3D nanoshape, the same way a single sheet of paper is folded into an origami crane by a sequence of individual creases — hence the name.
for each staple s in design order:
find scaffold regions (A, B) complementary to s
if unbound(A) and unbound(B):
pull A and B together, bind s
scaffold curvature updates near A, B
- Target shape — the folding pattern staples are designed against; a real caDNAno design encodes thousands of individual staple sequences for one target shape.
- Assembly speed — how fast staples are added in sequence; real annealing ramps temperature down slowly over hours so each staple finds its correct binding site before the next is tried.
- Staple count — fewer staples leave more of the scaffold unconstrained, so the folded shape is looser and less precise — mirroring how real designs trade staple density for cost.
- Fold RMS error — how far the current folded scaffold path is from the ideal target outline; it falls toward zero as enough staples lock the shape in place.
Real-world relevance: because each staple's binding site is set by its exact base sequence, the folded structure positions matter with nanometre precision — the same predictability now used to place proteins, fluorescent dyes and nanoparticles at programmed nanoscale coordinates for sensors, drug-delivery cages and nanofabrication templates.