Designing with DNA
No bigger than a virus, each of these nanostructures was built using new software that lets researchers design objects out of concentric rings of DNA. Models (top) shown alongside electron microscope images of the actual objects (bottom). Credit: Raghu Pradeep Narayanan and Abhay Prasad, Yan lab, Arizona State University.

It's easy to imagine you're looking at a catalog of the world's smallest pottery when you look at the structures emerging from research labs at Duke University and Arizona State University.

A new paper shows some of the teams' creations, including itty-bitty vases, bowls, and hollow spheres, which are hidden inside the other.

Instead of using wood or clay, the researchers designed these objects out of threadlike molecule of DNA, bent and folded into three-dimensional objects with nanometer precision.

There is a new open-source software program developed by a Duke student and his adviser. Users can use the software to turn drawings or digital models of rounded shapes into 3D structures made of DNA.

The co-authors of the book assembled and imaged the nanostructures in the lab of the professor. Two millionths of an inch is how deep each hollow object is. They could fit on top of a pin.

The researchers say these are more than just small sculptures. Researchers could use the software to create tiny containers to deliver drugs or make molds for casting metal nanoparticles for solar cells.

The blueprints of life are the genetic instructions for all living things. The source code and construction material of teams like Reif's andYan's are more important than the genetics of the project.

The four "letters" in the genetic code of DNA form the rungs of the ladder in our cells. The researchers have co-opted the strict base-pairing properties of the genetic material. They can program the strands to form different shapes by design.

The method involves folding one or a few long pieces of single-stranded DNA, thousands of bases long, with help from a few hundred short DNA strands that bind to the corresponding sequence on the long strands.

Since the 1980's, researchers have been experimenting with DNA as a construction material. Geometric shapes with coarse and blocky surfaces were the first 3D Shapes. It has been difficult to design structures that are similar to nature. The team wants to expand the range of shapes that can be achieved with this method.

Fu developed a software that could do that. The software is based on a way to build with DNA described in 2011. It works by coiling a long helix into rings that stack on each other to form the shape of the object. The team was able to reinforce the structures with more layers to make them stronger.

Fu shows off some of the different types of forms they can make. The first software tool that lets users design such shapes automatically is called DNAxiS, and it uses a method of determining where to place the short DNA "staples" to join the longer DNA rings.

The structure won't form correctly if there are too few or too many. The problem was made more difficult by the shape being curved.

The computer will spit out a list of strands that will fit into the right configuration if it is given a model of a mushroom. Once the strands are synthesised and mixed in a test tube, the rest takes care of itself by heating and cooling the DNA mixture within as little as 12 hours.

The researchers said that practical applications of their software in the lab or clinic are years away. It's a big step forward in terms of automated design of three-dimensional structures.

The Automated Design of 3D DNA Origami with Non-Rasterized 2D Curvature was written by Daniel Fu. Adv.ade4455

Journal information: Science Advances