[Paleopsych] Nanotech Gadgets to Be Built by Algae?

Steve Hovland shovland at mindspring.com
Wed Mar 30 12:08:02 UTC 2005

John Roach
for National Geographic News <http://news.nationalgeographic.com>
March 29, 2005
Ancient, single-celled organisms that are lowly anchors in the marine food 
chain may soon be integral players in the lofty realm of nanotechnology, 
the science of the very small.
Nanotech materials and devices measure less than a hundred nanometers, a 
unit of measurement that is one billionth of a meter. By contrast, a human 
hair is about 20,000 nanometers thick.
According to scientists and market analysts, the world is on the cusp of a 
nanotechnology revolution: The teeny, tiny materials and devices are 
beginning to show up everywhere from clothing and sporting goods to 
computer electronics and medical equipment.
But a limitation to the pending revolution is the high expense and 
inefficiency of making materials and devices at the nanoscale, according to 
Gregory Rorrer, a chemical engineer at Oregon State University in 
Rorrer believes a solution to the problem may lie in diatoms, single-celled 
marine life-forms that have been around since the age of the dinosaurs.
The algae are well known for their crucial role at the base of the marine 
food pyramid and for ridding the greenhouse gas carbon dioxide from the 
atmosphere. In addition, diatoms have a unique ability to pull silica from 
seawater and mill it into intricately-structured, rigid shells, Rorrer 
The organisms create their shells by employing special proteins and 
subcellular organs to first assemble silica nanoparticles, which are 
composed of just a few hundred atoms. The proteins and subcellular organs 
then orchestrate the assembly of those nanoparticles into shells, Rorrer 
"You've two levels of structure-these nanoparticles and then, what's way 
more interesting, is you can take these particles, and each one is like a 
little brick, and they are assembled into ornate microstructures," the 
chemical engineer said.
Last July Rorrer's lab at Oregon State University was awarded a four-year, 
1.3-million-dollar (U.S.) grant from the National Science Foundation to 
develop a process that harnesses diatom shell-construction to create 
nanostructured materials. (The foundation also funds National Geographic 
News's Pulse of the Planet news series, of which this story is a part.)
Products may include flexible computer screens, cheap and efficient solar 
cells, filtration devices, and drug delivery vehicles that can target, for 
example, a single cancer cell.
Rorrer's lab aims to incorporate elements such as silicon, germanium, 
titanium, and gallium into the diatoms' silica shells. At the nanoscale, 
these elements follow the laws of quantum mechanics instead of Newtonian 
physics, giving them unique and commercially desirable properties.
(Newtonian physics denotes well-known forces like gravity, while quantum 
mechanics describes laws of physics that apply at very small scales, such 
as those found in atoms.)
At the nanoscale, for example, the metal germanium glows blue when energy 
is applied to it. This has a host of applications in electronic and medical 
imaging technologies, Rorrer said.
The process to incorporate germanium nanoparticles in silica is "doable but 
difficult with existing technology," the scientist said.
The conventional process involves vaporizing a germanium crystal in a 
vacuum with a high-energy laser beam and coaxing the vaporized atoms to 
glom onto a silica surface.
"That has to be done at a high temperature [and] at a high vacuum and 
[with] all the equipment associated with the control of that," Rorrer said. 
"We do essentially the same thing by growing living organisms in a vat."
The trick for Rorrer and his Oregon State University colleague, Chih-hung 
Chang, is to add just enough dissolved metal to the vat to allow the 
diatoms to absorb it without dying.
To date "the concept for germanium incorporation has been proven," Chang 
said. "We will work on incorporating other metals very soon."
Another advantage to using diatoms, Rorrer said, is that when the algae 
divide, they make a perfect copy of themselves, meaning "we can make a 
gazillion of these, and they are all the same."
In addition to the ability of the diatoms to absorb these metals and create 
nanostructured materials, each diatom species makes shells with unique 
designs. And there are tens of thousands of diatom species.
Which means there are "tens of thousands of micro-templates," Rorrer said. 
"Some have holes, some ribs, some oval, some square-and all the 
microfabrication has been done by the organisms. We just put additional 
material on it."
In the future, the researchers hope they can use these diatoms to make 
intricate designs at the microscale that are currently not possible with 
existing technology.
To find the appropriate template, all a researcher would need is a 
searchable database of natural diatom designs. Genetic engineering may also 
one day make it possible to control diatom design.

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