Figure 1.

Illustrations of (a) S and (b) S_b are shown before (left) and after (right) invasion by the fuel strand f. The arms of the devices (α₁ and α₂) contain fluorescent labels, Iowa Black RQ (black circle) and FAM (red circle), respectively, that are quenched when the two sides are intact and fluorescent when they are separated. Toeholds (η) are depicted as gray, and the branch migration domain (μ) is depicted as blue. Depiction of the DNA motors with a hinge, (c) M and (d) M_b. A contracted motor (left) and an extended motor (right). The motor is held together by the hinge domain (H). The biased variants are created by replacing all of the guanines on the displaced side (red line) of the branch migration domain (μ) with inosine (inosines are depicted by hollow circles and natural bases by solid blue circles). The inosines were placed to create a forward-bias favoring branch migration to proceed from left to right.