(721c) Designed DNA Nanotube Architectures

Designed DNA Nanotube Architectures

Rebecca Schulman
and Abdul M. Mohammed

Chemical and
Biomolecular Engineering

Johns Hopkins
University

The cytoskeleton and extracellular matrix consist of
semiflexible biopolymers that are dynamically assembled into precise topologies
and continuously reassembled based on inputs from cells and environmental
signals.  This assembly process
leads to specific interactions of the resulting materials with cells that
enable tissue formation and can lead to properties such as the capacity for the
polymer matrix to self-heal or to reassemble continuously, producing motion of
the structure. Recapitulating the same assembly mechanisms synthetically is a
current challenge that would lead to new materials with novel biological
interactions and programmable, active reformation.

We report initial steps toward designing mechanisms to
synthetically control the topology of DNA nanotube architectures.  DNA nanotubes consist of units called
tiles, approximately 14x4 nm structures that self-assemble via DNA
hybridization. Tubes have a persistence length that depends on the radius; for
the structures we assemble it is estimated to be 10-20 microns.  We show that the nucleation and
termination of tubes can be efficiently directed at specific locations, with
the result being that we can create nanotube asters or point-to-point nanotube
links. Both nucleation and termination are guided by designed DNA complexes,
folded structures that emulate the facet of a growing DNA nanotube.  We characterize controlled nanotube
growth using both fluorescence light microscopy to track growth and atomic
force microscopy to characterize the structure of individual DNA nanotubes.