The carnival workers of this world would, no doubt, be greatly relieved if someone would hurry along the development of the self-assembling tent. Tent poles do not stand on their own. Miles of rope—and the muscle to pull them—are needed both to erect the poles of the big top and to stabilize them.
If only their circuses took place on the nanoscale, the carnival workers' toils would be at an end. The folks at Harvard’s Wyss Institute of Biologically Inspired Engineering have managed to create self-assembling structures of string and strut, just nanometers tall—out of DNA.
Why use DNA as a building block? Two reasons. First, there’s the depth of our knowledge about the molecule. “DNA really is the best,” says Donald Inber, director of the institute. “We know so much about it: We know the molecular biophysics—not only the chemistry, but the amount of force the molecule creates. It literally forms a spring.”
Second, DNA is, naturally enough, compatible with all things biological, making it an ideal tool for targeting specific cells in the body. Just as important, it’s also biodegradable.
DNA structures can be the size of a chemical, are fully programmable, and could conceivably do far more specific things in far more specific places.
Designing DNA structures and their sequence of assembly has more to do with traditional mechanical engineering (or perhaps origami) than it does with biology. The lion’s share of work is done on a CAD program. The software breaks up any delineated structure into “what looks like Lincoln Logs—like multihelical struts,” says Inber.
When the design is complete, the engineer orders the sequences. When the DNA arrives, it’s no more difficult than making a batch of instant coffee. “You put it in a tube, shake it, and wait,” says Inber. “You look at it under a microscope and there it is—it’s as weird and simple as that.”
The tiny creations floating around under the microscope are made of a single, long DNA strand folded up into the determined scaffold. Smaller strands have pulled the larger struts into place and continue to hold them there, much as bones are held in place by tendons and ligaments, and tent poles are hoisted and held by ropes.
The principle is one architects call tensegrity, and it acts no different on the nanoscale than it does on the macro, aside from its power to amaze. “It’s like a science-fiction manufacturing plant,” says Ingber.
The molecules could be programmed to change shape when they encounter the right kinds of cell. “You can have one cell bind in whole blood, for example,” says Ingber. “When it binds, it can trigger the structure to change shape.” That change could release a drug to a specific site. Or, better yet, the DNA construction could replace a drug all together.
Or even drugs in general. DNA structures can be the size of a chemical, are fully programmable, and could conceivably do far more specific things in far more specific places.
The institute is now “trying to move toward applications,” says Ingber. And the pharmaceutical industry better watch out. “It’s one of these paradigm shifts. It would really knock the field on its head,” he says. “It is futuristic, but we’re doing it.”
If you want to try your hand at folding a strand of DNA to your liking, head here: http://wyss.harvard.edu/viewpage/m-o/interactive-feature-molecular-origami
Michael Abrams is an independent writer.
Designing DNA structures and their sequence of assembly, has more to do with traditional mechanical engineering (or perhaps origami) than it does with biology.
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