Engineers build DNA 'nanotowers' with enzyme tools

Source: KurzweilAI.net, Oct. 13, 2005

Engineers build DNA 'nanotowers' with enzyme tools

Duke engineers are creating the tools that will make bio-
manufacturing possible at an industrial scale.

"The development of bio-nanotechnological tools and fabrication
strategies, as demonstrated here, will ultimately allow the
automated study of biology at the molecular scale and will drive our
discovery and understanding of the basic molecular machinery that
defines life," said Stefan Zauscher, assistant professor of
mechanical engineering and materials science.

They can vertically extend short DNA chains attached to nanometer-
sized gold plates, using an enzyme called TdTase. The team starts
with a forest of short DNA strands that cover nanoscale patches of
gold, lithographed onto a silicon substrate. The researchers then
submerge the substrate in a solution that contains the TdTase
(terminal deoxynucleotidyl transferase) enzyme, a cobalt catalyst
and the molecular building blocks, called nucleotides, of DNA
chains.

Over an hour, the TdTase enzyme grabs the free-floating nucleotides
and builds nanoscale "towers" above the surface by extending each
DNA strand, increasing its height a hundredfold. In addition, the
process works at room temperature in an incubator that maintains
humidity.

Ashutosh Chilkoti, associate professor of biomedical engineering at
Duke's Pratt School of Engineering, said the next step towards bio-
nanofabrication is to create a little crane to pick up, move and
place biological molecules in precise locations on three-dimensional
DNA surfaces.

"When we can place molecules in the right configuration, then we can
get them to function. At that point, we can design and create
biological machines that accomplish something,"