Biomedical Engineering Reference
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the doubly thiolated DNA ligands appeared as a ladder of well-separated gel bands
during agarose gel electrophoresis, which could be eluted from the gel without
any destabilization problems (see Fig.
8.14
b). Our further work will make use of
the valence-controllable synthesis of AgNP-DNA conjugates for various purposes
including DNA-guided material assembly and the adaptation of this strategy to more
materials.
8.5
Summary and Outlook
DNA nanotechnology is experiencing a transition from structural controls to
functional explorations. Inorganic nanomaterials have rich physical and chemical
properties, but lack a programmable and highly parallel way to assemble them
into desired structures. The marriage between structural DNA nanotechnology and
materials science is therefore a very promising research direction to address this
challenge. Through the efforts of the past several years, several key breakthroughs
have been achieved, and new assembly strategies and materials have emerged,
including the development of new building blocks that may produce novel functions
for DNA-directed nanophase materials. On the other hand, surface-assisted nanopar-
ticle decoration and the involvement of DNA origami have enabled site-specific
DNA or nanoparticle attachment, which used to be a very difficult task. Carbon
nanotubes and gold nanorods have been employed to demonstrate an orientation
control of one-dimensional nano-objects on a DNA landscape, which is of great
significance for nanodevice fabrications. One-pot synthesis of nanoparticle-DNA
conjugates with a specific valence of the DNA ligands is now possible in the case of
quantum dots. Besides gold nanoparticles that have achieved an overwhelming use
for more than a decade, platinum and silver nanoparticles decorated with a discrete
number of DNA ligands are now available for valence-controlled nanoparticle
assembly toward more versatile functions.
In view of the most recent progresses, we can now have a more complete list
of DNA-conjugated and DNA-guided nanophase materials, which should include
the following: (1) periodically ordered and highly addressable nanoparticle arrays
based on tile-assembled DNA lattices or DNA origami, (2) hierarchical and discrete
nanostructures directed by designed DNA linkages, (3) chiral nanophase materials
with tunable handedness and optical activity, (4) surface-assembled nanostructures
that may not be attainable in a homogeneous solution, (5) gold and non-gold
building block materials with precisely controlled DNA bonding valence, and
(6) heteronanostructures formed between compositionally and morphologically
distinct nano-objects toward synergistic functions. Research toward these direc-
tions will attest to the versatility and programmability of DNA molecules, which
will keep evolving and expanding to incorporate more elements, functions, and
applications.
With the continuous development of DNA-directed nanophase materials and
their rapid branching into more disciplines, some challenges will be faced for
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