Duke University scientists are using self-assembling DNA molecules to build molecular meshes which can expand and contract, according to "Switchable net woven from DNA," published by Nature. Here are some excerpts.
US researchers have woven DNA into a net that expands and contracts1. It could be used as a nano-filter or in biological sensors.
It might even be the basis of a computer that has as its components lumps of metals or semiconductors just a few millionths of a millimetre -- nanometres -- wide. The switchable DNA net could turn electrical communication between these devices on and off by altering the distance between them.
In a sensor containing an array of proteins that latch onto other biological molecules, the mesh might activate or deactivate the process by plugging and unplugging the cavities of sensor molecules that bind their targets.
But how can we use these switchable DNA nets?
For example, the mesh-making team -- Hao Yan and colleagues at Duke University in Durham, North Carolina -- has also devised X-shaped DNA tiles that link up into a square grid2. Proteins can be arranged on this scaffold, by hooking them to the middle of an X. Coating the grid with silver creates a lattice of nano-wires, which could be used in ultra-miniature electronic circuits.
Here is a picture of these X-shaped DNA tiles. (Image: Copyright Science)
For more information, you also can read this Duke University news release, "Duke scientists 'program' DNA molecules to self assemble into patterned nanostructures."
"Our goal is to use DNA self-assembly to precisely control the location of other molecules," said Yan, a molecular chemist working as an assistant research professor in Duke's computer science department.
"The big promise is that if we can increase the size of our lattices we can template nanoelectronics onto them and make useful devices and circuits at a smaller scale than has ever been done before," added LaBean, a molecular biologist who is also an assistant research professor of computer science.
Ready for some technical explanations?
The Duke team [said) that they could make the DNA strands arrange themselves into cross shaped "tiles" capable of forming molecular bonds on all four ends of the cross arms. As a result, large numbers of the crosses could naturally stick together to form semi-rigid waffle-patterned arrays that the authors called "stable and well behaved."
Since two types of DNA component units called bases selectively pair up with the two others to form DNA strands -- that is, adenine with thymine and guanine with cytosine -- the scientists could exploit those biochemical properties to program different ways for their tiles to link together.
When the tiles were programmed to link with their faces all oriented in the same up or down direction, they self-assembled into narrow and long waffled "nanoribbons." But when each tile's face was programmed to point in the opposite direction from its neighbor, wider and broader waffled "nanogrids" were formed, the authors wrote.
In the case of the nanogrids, the authors found they could affix protein molecules to the cavities that the DNA tiles naturally formed at the center of each cross.
To affix the proteins, they first attached the chemical biotin to parts of the DNA strands they knew would self-assemble in the cavities. Then they added the protein streptavidin to the solution containing self assembled nanogrids. As a result, the biotin and streptavidin bound, in a reaction familiar to protein chemists. So complexes of protein molecules assembled atop those cavities.
If you want even more information and references, you can read "Programmable DNA Lattices: Design Synthesis and Applications."
Sources: Philip Ball, Nature, September 26, 2003; Duke University news release, September 25, 2003
1:45:48 PM Permalink
|
|
