Northwestern University researchers report they have used DNA as the blueprint, contractor and construction worker to build a three-dimensional structure out of gold, a lifeless material. Using just one kind of nanoparticle (gold) the 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. The technique ... is a major and fundamental step toward building functional designer" materials using programmable self-assembly. "We are now closer to the dream of learning, as nanoscientists, how to break everything down into fundamental building blocks, which for us are nanoparticles, and reassembling them into whatever structure we want that gives us the properties needed for certain applications," said Chad A. Mirkin, one of the paper's senior authors. The structures that finally form are the ones that maximize DNA hybridization. DNA is the stabilizing force, the glue that holds the structure together. "These structures are a new form of matter," said Mirkin, "that would be difficult, if not impossible, to make any other way."

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