DNA used to make different lifeless gold nanoparticle structures

Most gems, such as diamonds, rubies and sapphires, are crystalline inorganic and inert materials. Within each crystal structure, the atoms have precise locations, which give each material its unique properties. Diamond’s renowned hardness and refractive properties are due to its structure — the precise location of its carbon atoms.

Using just one kind of nanoparticle (gold), North West University researchers built two common but very different crystalline structures by merely changing one thing — the strands of synthesized DNA attached to the tiny gold spheres. A different DNA sequence in the strand resulted in the formation of a different crystal. DNA becomes the blueprint, contractor and construction worker to build a three-dimensional structure out of gold, a lifeless material.

The novel part of their work is that the researchers use DNA to drive the assembly of the crystal. Changing the DNA strand’s sequence of As, Ts, Gs and Cs changes the blueprint, and thus the shape, of the crystalline structure. The two crystals reported in Nature, both made of gold, have different properties because the particles are arranged differently.

This is a major and fundamental step toward building functional “designer” materials using programmable self-assembly. This “bottom-up” approach will allow scientists to take inorganic materials and build structures with specific properties for a given application, such as therapeutics, biodiagnostics, optics, electronics or catalysis.

The paper’s senior authors – Chad Mirkin, George Rathman, George Schatz and their team just used one building block, gold spheres, but as the method is further developed, a multitude of building blocks of different sizes can be used — with different composition (gold, silver and fluorescent particles, for example) and different shapes (spheres, rods, cubes and triangles). Controlling the distance between the nanoparticles is also key to the structure’s function.

For further information:

http://www.northwestern.edu/newscenter/stories/2008/01/dnamirkin.html

Elaine Warburton www.geneticsandhealth.com