Biomedical Engineering Reference
In-Depth Information
DNA nanotechnology, including modified DNA bases (e.g., biotinylated). Another
catalyst for the rapid development of DNA nanotechnology came from the invention
and commercialization of atomic force microscopy (AFM). AFM, as a member of
scanning probe microscopy (SPM), can readily probe almost any samples deposited
at flat surfaces and perform measurements in three dimensions, x, y, and z, thereby
enabling the visualization of three-dimensional images of a given sample. AFM,
together with more recently developed technologies such as cyro-EM and super-
resolution fluorescent microscopy, provides a powerful set of toolbox for in-depth
characterization of self-assembled DNA nanostructures. With these technological
advances, numerous art-like elegant DNA nanostructures rapidly appeared, greatly
boosting the growth of this area.
In 1994, Adleman reported a DNA-based “wet-lab” solution for solving a
computational problem [ 7 ], which can arguably be regarded as one of the first
applications of DNA nanostructures in biological computing. Indeed, an area full
of nice structures (toys) without any applications cannot last long. Nearly a decade
ago, researchers started to rationally control variation of DNA nanostructures with
external triggers, which extended the area of DNA nanotechnology from structure
to function. One of the most attractive directions is to convert static DNA nanos-
tructures to dynamic, functional DNA “nanomachines” or DNA “nanodevices.”
An early, elegant example of DNA nanomachines is “DNA tweezers” reported
by Turberfield and Simmel in 2000 [ 8 ]. “DNA tweezers” were composed of two
DNA duplexes, which were connected by a short single strand acting as a flexible
hinge and which resemble a pair of open tweezers. The tweezers were then closed
by adding a “set” strand that the tweezers' ends could hybridize with. Reopening
of the tweezers was realized by using a “reset” strand that was attached to a
toehold on the set strand, which displaced the set strand from the tweezers through
branch migration. Visualization of the opening and closing of the tweezers was
fluorescently monitored by using a FRET pair attached to the two ends of the
tweezers.
The advance of DNA nanotechnology also benefited greatly from the rapid devel-
opment of another rapidly emerging area, functional nucleic acids (FNAs) (aptamers
and DNAzymes). Aptamers are artificially in vitro selected single-stranded DNA or
RNA with antibody-like high affinity and specificity [ 9 ]. Ribozymes or DNAzymes
are artificial selected nucleic acid with enzyme-like catalytic activities [ 10 , 11 ].
FNAs have many superior advantages over antibodies or enzymes, e.g., they can
be readily chemically synthesized with low cost and high purity, and they are
much more stable. In addition, they are inherently fully compatible with DNA
nanotechnology since both are nucleic acids. The introduction of FNA into DNA
nanostructure fertilized versatile applications of DNA nanotechnology, leading to
the development of functional DNA nanostructures for biosensing, nanoplasmonics,
and nanorobotics.
There appeared milestone work in DNA nanotechnology in 2006, i.e., DNA
origami invented by Rothermund [ 12 ]. This great strategy was inspired by the
ancient Asia paper-cutting art (origami is the pronunciation of Japanese, but might
be originated from China). In brief, DNA origami involves raster-filling a designed
Search WWH ::




Custom Search