Nanotech Gadgets to Be Built by Algae?

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 Corvallis.

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 said.

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 said.

"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.

Nanomaterials

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.

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