By Richard Acello
Small Times Correspondent
SAN DIEGO, Jan. 22, 2002 — Scientists are studying how nanotechnology can fight sudden invasions of brown tide and other forms of algae harmful to the seafood industry.
“Clams stop feeding and they starve to death,” said David Caron, a professor of biological sciences at the University of Southern California. “The Long Island scallop and clam industries lose millions of dollars to brown tide.”
But brown tide isn’t the only scourge lurking in the oceans. Urban runoff, sewage spills, and other harmful microorganisms pose a health threat to human and marine life. With a
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| A brown tide cell: Seafood industry’s public enemy No. 1. |
Using colloidal gold and silver balls as small as two nanometers, a group led by chief investigator and computer science professor Ari Requicha programs a computer-controlled atomic force microscope — a kind of scanning probe microscope — to slide gold balls onto slides mica or silicon. In this way, Requicha and Caron hope to attach antibodies to the sharp silicon tip (about 10 nanometers) of the microscope probe to interact with a sample.
“We’re going to go fishing,” Requicha explained. “When there’s an interaction between the antibodies and a corresponding antigen, it will bind” to the tip of the probe. This can be done at room temperature and in water, Requicha added.
Identifying pathogens in this way, Requicha said, takes minutes or hours, instead of days. Time is of the essence in warning the fishermen of brown tide, surfers of harmful bacteria or the existence of toxic agents in drinking water.
From the lab, Requicha plans to move his experiments to a 5-by-5-foot tank with microscopic robots searching for microorganisms. The group has already constructed a nanoscale single-electron transistor and an optical waveguide, used to guide light. The group is also working on a nanosize actuator or switch, and is starting to assemble 3-D nanostructures by building up successive layers of nanoscale assemblies.
But Requicha is still wrestling with ideas on how to make his robots mobile. “How do you get the robots to propel themselves or to swim?” he asks. “One idea is they could be propelled like bacteria with flagella.”
Eventually, though, the team wants to create robots that are as small as the microorganisms that they seek to monitor. In any event, Requicha said he’ll be ready to move his early stage robots into the ocean “in a couple of years or so.”
But the Holy Grail of the technology, said Requicha, is its use in the human body. “If you can make a system that can detect microorganisms in a marine environment, it could be deployed in blood. If you were successful, you could have artificial cells, you could program an artificial immune system for those with impaired immune systems. The possibilities are amazing.”