DNA NANOTECHNOLOGY AND ITS BIOLOGICAL APPLICATIONS - Bio-Inspired and Nanoscale Integrated Computing - page 372

52

A*

B C

I
Ligase

A ∗ B C

68

II
PflM I

B ∗

A C

19

III
Ligase

B ∗ C

A

57

4

IV
Bstap I

41

C ∗ A B

Figure 13.21. Operation of autonomous molecular transport devices self-assembled
from DNA.

''feet'') assembled on one end of the road, with the feet of the walker hybridized to
the first two steps of the road.
Then, as illustrated in Figure 13.21, the walker proceeded to make sequential
movement along the road, where at the start of each step, the feet of the walker are
hybridized to two consecutive steps of the road. Then a restriction enzyme cuts the
DNA helix where the backward foot is attached, exposing a new sticky-end
forming and a new replacement foot that can hybridize to the next step that is
free, which can be the step just after the step where the other foot is currently
attached. A somewhat complex combinatorial design for the sequences composing
the steps and the walker ensures that there is unidirectional forward motion along
the road.