English: Formation gel of a DAO double-crossover (DX) DNA molecule used in DNA nanotechnology. This is a polyacrylamide gel run under native conditions. The molecule has four strands, here labeled 1 through 4, and each lane contains a different combination of the strands. The lanes, from left to right, are: 10 base pair ladder, 1+2+3+4 (full DX), empty, 1+2+3, 1+2+4, 1+3+4, 2+3+4, empty, 1+2, 1+3, 1+4, 3+4, 2+4, 2+3, empty, 1, 2, 3, 4.