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In this machine DNA hybridization is used to push two components apart rather than to pull them together. In addition, the nanoactuator is less susceptible to dimer formation than are the molecular tweezers.
The molecular machine is constructed from two strands of DNA labelled A and B that hybridize to form a loop with two 18-base-pair double-stranded regions.
Strand A was labeled at the 5’ and 3’ ends with the dyes TET and TAMRA, respectively. Fluorescence resonance energy transfer ~FRET between these two dyes was used to monitor the separation between the two arms of the actuator.
The 48-base region of B that remains single stranded consists of a 40-base region, M of Table I, which we refer to as the motor domain.
The motor domain is sandwiched between the two four-base regions SB1 and SB2 that serve as spacers.
Finite yet complex structures are built using the simplest tile form, a ‘single-stranded tile’ (SST)
It consists of a 42-base strand of DNA composed entirely of concatenated sticky ends and that binds to four local neighbours during self-assembly.
The ss-DNA is folded into a 3nm-by-7nm tile and attached to four neighbouring tiles—acting as a pixel.
A desired shape, drawn on the canvas, is then produced by one-pot annealing of all those strands that correspond to pixels covered by the target shape; the remaining strands are excluded.