Ars Technica: Creating specific shapes from nanoparticles can be difficult, but a new technique to create molds from DNA may provide a way to scale up the production of nanomaterial structures. In DNA, the patterns of the base pairs determine the shape that the molecule folds into. Computational modeling allowed researchers to create self-assembling DNA molecules that fold into 3D structures. Those structures then serve as molds for nanometals. A tube and two lids were made out of DNA. Then a gold nanoparticle was attached to the inside of the tube, which was sealed with the lids. Placed in a solution with dissolved gold atoms, the nanoparticle grows until it fills the tube. Then, silver nitrate and ascorbic acid were added to the solution, which caused the silver to bind to the gold inside the mold. The result was three silver cuboids. Further work created complex structures including a sandwich of silver trapped between two quantum dots, which could couple with electromagnetic radiation at wavelengths larger than the structure.
