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E.Coli bacterium
is being used as a primary part of tiny, implantable drug
dispensers. The implantable dispensers can take the place
of repeated insulin or chemotherapy injections and can also
provide blood samples without using needles.
Several methods
are already underway to create smaller implants. One such
method uses microelectromechanical systems with gears the
size of a grain of pollen. However, the systems have very
high internal pressure, which causes them to leak.
Nonmechanical designs
are another method, which use electrical voltage to move fluid.
However, these devices can only dispense particular drugs
because they rely on electrical properties of the fluid.
Researchers then
turned to E. coli bacterium as an option, calling it "the
world’s smallest living motor." The bacteria, which
naturally spin either clockwise or counterclockwise, are modified
so that they all rotate in the same direction. When they are
planted in the dispenser their spin pushes the drug out of
the dispenser.
The E.coli bacterium,
widely known for its potentially deadly effects, has also
been genetically altered to be harmless in the body. Still,
some believe it will be a challenge to get the device approved
by regulatory agencies.
Another challenge
researchers face is how to seal the device. When the device
is open the cells can live, however, when it is closed the
cells begin to die.
Nonetheless, researchers
estimate that a working prototype will be ready within two
years, and suggest that it will be available commercially
in five to 10 years.
Wired
News February 28, 2003
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