DNA process stamps patterns

Many researchers are tapping DNA's ability to spontaneously assemble in order to make objects on the molecular scale.

Researchers from the Massachusetts Institute of Technology and Virginia Commonwealth University have devised a way to stamp patterns made of single-stranded DNA molecules onto a surface. The method also makes it possible to convert patterns composed of other material into DNA.

The method could be used to print microarrays of DNA that can be used for medical research and diagnosis. It could also be used to print many types of devices, including tiny channels that shunt fluids around biochips, optical biosensors and transistors, according to the researchers.

One of the main challenges of nanotechnology is developing methods of making objects in parallel to enable mass production. One of the advantages of the researchers' stamping method is that each pattern produced by a stamp can, in turn, be used as a stamp.

The technique can transfer patterns whose features are as small as 30 nanometers. A nanometer is one millionth of a millimeter, or the span of 10 hydrogen atoms. The researchers used the method to stamp lines, circles and squares.

To make a stamp, the researchers used lithography -- etching using light and chemicals -- to produce a master copy of the pattern, then chemically attached a set of DNA strands to it. They then attached another set of DNA strands to the first set, attached the chemically-modified ends of those strands to a surface, and detached the second set of DNA strands from the first to produce the stamped pattern.

In theory, the method will work with any pairs of molecules that recognize and attach to each other, then can be detached, including antibodies and antigens, according to the researchers. The stamped patterns can also be modified. The researchers added metal and fluorescent molecules to some of their prototype stamp patterns.

The work appeared in the June 13, 2005 issue of Nano Letters (Supramolecular Nanostamping: Using DNA as Movable Type).