Chemists have become very skilled at building 2-D nanostructures, but making 3-D patterned structures for drug delivery, electronics and other applications has proved more challenging. In particular, no one has been able to make 3-D structures with patterned surfaces.
David Gracias and Jeong-Hyun Cho of Johns Hopkins University in Baltimore have overcome this problem. They first made arrays of patterned, cross-shaped nickel structures on a silicon wafer, then added tin hinges. When placed in a plasma etching chamber, the flat structures folded up into cubes and released from the wafer. To make nanocubes as small as 100 nanometers a side, the researchers added another panel.
The work is described online in the journal Nano Letters, where the researchers write that it should apply to other polyhedral shapes as well.