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Designing with DNA

Look at the tiny nanoscale structures emerging from research labs at Duke University and Arizona State University, and it’s easy to imagine you’re browsing a catalog of the world’s smallest pottery.

A new paper reveals some of these creations: itty-bitty vases, bowls and hollow spheres, one hidden inside the other, like housewares for a Russian nesting doll.

But instead of making them from wood or clay, the U.S. National Science Foundation-supported team of researchers designed these objects out of threadlike molecules of DNA, bent and folded into complex 3D objects with nanometer precision.

These creations demonstrate the possibilities of a new open-source software program developed by Duke researchers Dan Fu and John Reif. Described in the journal Science Advances, the software lets users take drawings or digital models of rounded shapes and turn them into 3D structures made of DNA.

The DNA nanostructures were assembled and imaged by ASU researchers. Each tiny hollow object is no more than 2 millionths of an inch across. More than 50,000 of them could fit on the head of a pin.

But the researchers say these are more than mere nano-sculptures. The software could allow researchers to create tiny containers to deliver drugs or molds for casting metal nanoparticles with specific shapes for solar cells, medical imaging and other applications.

To most people, DNA is the blueprint of life -- the genetic instructions for all living things, from penguins to poplar trees. But to these researchers, DNA is more than a carrier of genetic information; it’s source code and construction material.

Researchers have been experimenting with DNA as a construction material since the 1980s. The first 3D shapes were simple cubes, pyramids, soccer balls -- geometric shapes with coarse and blocky surfaces. But designing structures with curved surfaces more akin to those found in nature has been tricky. The team’s aim is to expand the range of shapes that are possible with this method.

To do that, Fu developed software called DNAxiS. The software relies on a way to build with DNA developed by ASU researchers. It works by coiling a long DNA double helix into concentric rings that stack on each other to form the contours of the object, like using coils of clay to make a pot. To make the structures stronger, the team also made it possible to reinforce them with additional layers.

Practical applications of the DNA design software in the lab or clinic may still be years away, the researchers said, but it's a step forward in automated design of new 3D structures.