We've reported on the use of nanotechnology to develop better composites, fault-detecting paint, and energy-harvesting wearable fabric. It's also a methodology for developing devices that assemble themselves. Though many of those efforts have used carbon nanotubes, Harvard University's Wyss Institute for Biologically Inspired Engineering has harnessed DNA to create self-assembling nanodevices.

The emerging field of DNA nanotechnology is being explored for building tiny, programmable structures for diverse applications. So far, most research has focused on what's called DNA origami. This method uses a long biological strand of DNA as a backbone. Smaller strands are bound to its segments to create different shapes.

Researchers at the Wyss Institute took a different approach. A team led by Peng Yin, a Wyss core faculty member and assistant professor of systems biology at Harvard Medical School, used short synthetic strands of DNA to build complex nanostructures. These interlocking building blocks, called single-stranded tiles (SSTs), can be programmed to assemble themselves into precisely designed shapes.

Each SST consists of a unique 42-base DNA strand that folds into a 3nm x 7nm tile and binds to four local neighbors during self-assembly if they have complementary DNA sequences. Through a series of these interlocking connections, a group of SSTs can assemble themselves into different shapes. (You can watch a slideshow presentation with audio narration here.)

The researchers created more than 100 different designs (including numbers, letters, and Chinese characters) out of these tiles to demonstrate the DNA assembly method. For a single structure 100nm long, they used hundreds of tiles.

As synthetically based materials, the SSTs could have some important applications in medicine. They could organize themselves into drug delivery machines that maintain their structural integrity until they reach specific cell targets. Because they are synthetic, they can be tailored to be highly biocompatible.

The researchers, including Wyss postdoctoral fellow Bryan Wei and graduate student Mingjie Dai, say the approach is simple, versatile, and robust. They envision it as being developed for nanoscale devices for highly targeted drug delivery, among other applications.

The National Science Foundation, the National Institutes of Health, the Office of Naval Research, and the Wyss Institute supported this research.

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