Excerpts covering DNA nanotechnology from Technology Research News interview with New York University chemistry professor Nadrian Seeman

Full interview: http://www.trnmag.com/Stories/2005/050405/View_Nadrian_Seeman_050405.html

TRN: Tell me about the trends in research on the technological uses of DNA. What are the pluses and minuses of today's DNA technology research priorities? What do you see as the most urgent needs in these areas?

Published by

Seeman: DNA nanotechnology is still a field in its infancy, so it is in an era of "100 flowers blooming".

Many of us believe that DNA offers a powerful bottom-up method for the organization of nanoelectronic components.

I suggested 25 years ago that DNA could organize lattices to facilitate macromolecular crystallization, both for academic purposes and for drug discovery.

Nanorobotics is a coming area with many applications, from novel materials to nanotherapy. More government money needs to be directed to these efforts. Most of the practitioners in the area are scrambling for support. My sense is that the most urgent need is to develop high-resolution 3D periodic or pseudo-periodic arrays.

The most pressing technical problem is the lack of a convenient inexpensive method for purifying synthetic DNA strands of the lengths used (up to 150-mers) to chemical levels of purity.

...

TRN: What makes DNA particularly useful for nanotechnology, and what does it lack?

Seeman: It is important to realize that DNA is largely used in nanotechnology in branched motifs, which are easy to design, from both the perspectives of molecular architecture and sequence assignment.

It is possible to self-assemble these branched motifs into objects, periodic and aperiodic arrays and nanomechanical devices. It is possible to direct the assembly processes with high specificity using sticky ends and other cohesive interactions. This gives us an enormous range of structural possibilities, limited only by the imagination.

It is the molecule whose intermolecular interactions are best predictable, both regarding affinity and structure.

In addition, it is a stiff molecule, with a persistence length of 50 nanometers in normal conditions; it is convenient to make; there are commercially-available modifying enzymes; it is robust up to 90 degrees C; it is amenable to biotechnology methods; it has an externally readable code even when it is in the double helical form; it has functional groups every .34 nm along the helix axis where it can be derivatized; there are hundreds of derivatives of DNA with varied properties.

As for deficiencies, like any molecule, its overall physical properties may not be exactly suited to a particular application.

TRN: What do you mean by "structural purposes".

Seeman: I mean using 3D DNA lattices to act as a host lattice to scaffold guest biological macromolecules in periodic arrays for crystallographic structure determination.

TRN: Can you give me a brief explanation of sticky ends?

Seeman: If a double helix is made with strands that are not the same length, one strand will overhang one of the ends. This overhang, say 4 to 8 nucleotide units is called a 'sticky end'. If another double helical molecule has a complementary sticky end, the two double helices will cohere.

...

TRN: Nanotechnology is a broad, vague term encompassing the cutting edges of biochemistry, inorganic chemistry, materials science and electrical engineering. What does the term mean to you, and what of the many, well-hyped promises of nanotechnology do you see as plausible and which do you see as likely?

Seeman: My favorite one-line definition derives from Carlo Montemagno, "Nanotechnology is taking what you want and putting it where you want it and getting it to do what you want it to do, all on the nanometer scale." I think we'll be able to do that in many systems in the foreseeable future. The applications noted above are all plausible.

Technology Research News: www.trnmag.com