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Research Teams Use DNA To Make 3-D Nanoparticle Structures With High Precision

Nanotechnology: One group assembles nanoparticle lattices that can be reshaped on demand, and the other builds structures that mimic the geometry of diamond

by Celia Henry Arnaud
February 5, 2016 | A version of this story appeared in Volume 94, Issue 6

Credit: Adapted from AR Tao, Science 351:6273 (2016); Illustration by N Cary.
Schematic showing DNA control of nanoparticle building blocks.
Credit: Adapted from AR Tao, Science 351:6273 (2016); Illustration by N Cary.

DNA strands anchored to the surface of nanoparticles allow researchers to assemble the particles into three-dimensional crystalline lattices. Such control allows researchers to make new materials with desirable properties. In two recent studies, independent teams adapted this approach to gain even more control over assembly.

Schematic showing DNA control of nanoparticle building blocks.
Credit: Adapted from AR Tao, Science 351:6273 (2016); Illustration by N Cary.
Gang’s team formed a diamond lattice using a DNA origami cage (top). Mirkin’s team used DNA hairpins that can open to make particles switch between lattice geometries (bottom).

One team, led by Chad A. Mirkin of Northwestern University, designed “transmutable” DNA-coated nanoparticles that can switch from one lattice structure to another on demand in response to chemical cues (Science 2016, DOI: 10.1126/science.aad2212).

To do that, Mirkin’s team coats the nanoparticle surface with DNA that folds back on itself in hairpin loops. The addition of short oligonucleotides complementary to the loops disrupts the hairpins and exposes a DNA recognition sequence that can bind to sequences on other nanoparticles. By using multiple hairpins that bind to different sequences, the researchers can cycle a given nanoparticle mixture between lattice structures by changing which hairpins are opened or closed.

“Until now, all DNA-programmable nanoparticles have been designed to build one particular structure. To get another structure, you must make a whole new batch of nanoparticles with different DNA linkers attached,” says Sharon C. Glotzer, a materials scientist at the University of Michigan. “With this breakthrough, one can embed multiple potential structures into a single batch of identical nanoparticles and then select the desired structure on demand. The nanoparticles are now transmutable.”

The other team, led by Oleg Gang of Brookhaven National Laboratory, made DNA nanoparticle structures with the same crystal lattice as diamond (Science 2016, DOI: 10.1126/science.aad2080). Scientists have been trying to make this structure for decades, Gang says.

His team succeeded by combining DNA-coated nanoparticles with tetrahedral cages made with DNA origami. Short, single-stranded DNA sequences on the tetrahedron bind to the DNA coating on the particles. One nanoparticle is trapped inside each tetrahedron; four others are attached to the vertices of the tetrahedron, mimicking the geometry of carbon in diamond.

Gang’s strategy marks the first time DNA origami has been combined with DNA-mediated nanoparticle assembly, Glotzer notes. Such an approach will lead to more complex assemblies than are accessible by more traditional approaches alone, she says.

“Combining Mirkin’s transmutable DNA strategy with Gang’s DNA cages could lead to pluripotent nanomaterials of extraordinary complexity down the road,” Glotzer says.



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