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Researchers Create Versatile 3D Nanostructures Using DNA "Bricks"

NanostructuresBoston, MA -- Researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University have created more than 100 three-dimensional (3D) nanostructures using DNA building blocks that function like Lego® bricks -- a major advance from the two-dimensional (2D) structures the same team built a few months ago.

In effect, the advance means researchers just went from being able to build a flat wall of Legos®, to building a house. The new method, featured as a cover research article in the 30 November issue of Science, is the next step toward using DNA nanotechnologies for more sophisticated applications than ever possible before, such as "smart" medical devices that target drugs selectively to disease sites, programmable imaging probes, templates for precisely arranging inorganic materials in the manufacturing of next generation computer circuits, and more.

Computer-generated 3D models (left) and corresponding 2D projection microscopy images (right) of nanostructures self-assembled from synthetic DNA strands called DNA bricks. A master DNA brick collection defines a 25-nanometer cubic "molecular canvas" with 1000 voxels. By selecting subsets of bricks from this canvas, Ke et al. constructed a panel of 102 distinct shapes exhibiting sophisticated surface features as well as intricate interior cavities and tunnels. These nanostructures may enable diverse applications ranging from medicine to nanobiotechnology and electronics. [Image Credit: Yonggang Ke, Wyss Institute, Harvard University.]

Building with DNA bricksThe nanofabrication technique, called "DNA-brick self-assembly, " uses short, synthetic strands of DNA that work like interlocking Lego® bricks. It capitalizes on the ability to program DNA to form into predesigned shapes thanks to the underlying "recipe" of DNA base pairs: A (adenosine) only binds to T (thymine) and C (cytosine) only binds to G (guanine).

But there's a "twist" in the new method required to build in 3D.

The trick is to start with an even smaller DNA brick (32 bases in length), which changes the orientation of every matched-up pair of bricks to a 90 degree angle -- giving every two Legos® a 3D shape. In this way, the team can use these bricks to build "out" in addition to "up, " and eventually form 3D structures, such as a 25-nanometer solid cube containing hundreds of bricks. The cube becomes a "master" DNA "molecular canvas"; in this case, the canvas was comprised of 1000 so-called "voxels, " which correspond to eight base-pairs and measure about 2.5 nanometers in size - meaning this is architecture at its tiniest.

The master canvas is where the modularity comes in: by simply selecting subsets of specific DNA bricks from the large cubic structure, the team built 102 3D structures with sophisticated surface features, as well as intricate interior cavities and tunnels. "This is a simple, versatile and robust method, " says Peng Yin, Ph.D., Wyss core faculty member and senior author on the study.

The DNA-brick technique capitalizes on the ability of DNA strands to selectively attach to other strands, thanks to the underlying "recipe" of DNA base pairs. This animation shows how the DNA strands self-assemble to build a structure.

Another method used to build 3D structures, called DNA origami, is tougher to use to build complex shapes, Yin said, because it relies on a long "scaffold" strand of DNA that folds to interact with hundreds of shorter "staple" strands - and each new shape requires a new scaffold routing strategy and hence new staples. In contrast, the DNA brick method does not use any scaffold strand and therefore has a modular architecture; each brick can be added or removed independently.

ProQuest, UMI Dissertation Publishing Hydrothermal growth and characterization of titanium dioxide nanostructures for use in dye sensitized solar cells.
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Science, it's hard for RWers

by ProudCommunist

May 30, 2013
When Felix Fischer of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) set out to develop nanostructures made of graphene using a new, controlled approach to chemical reactions, the first result was a surprise: spectacular images of individual carbon atoms and the bonds between them.
"We weren't thinking about making beautiful images; the reactions themselves were the goal," says Fischer, a staff scientist in Berkeley Lab's Materials Sciences Division (MSD) and a professor of chemistry at the University of California, Berkeley

Nanotubes Increase Solar PV Conductivity 100 Million-Fold  — Sourceable
Carbon-based nanostructures are already being used as materials in solar cells with increasing frequency, yet their ability to enhance electrical performance has thus far been hampered by limited ability to assemble orderly networks using the materials.

BiblioGov Improved Solar Cell Efficiency Through the Use of an Additive Nanostructure-Based Optical Downshifter
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Elsevier Preparation of functionalized nanostructures on microchannel surface and their use for enzyme microreactors [An article from: Chemical Engineering Journal]
Book (Elsevier)
Nova Science Publishers Hybrid Nanostructures in Cancer Therapy (Cancer Etiology, Diagnosis and Treatments: Nanothechnology Science and Technology)
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