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A shrinking world inside
agriculture
Fantastic
voyage
In
the 1966 sci-fi movie Fantastic Voyage, a team of scientists
is shrunk to micro size so that they can save the life of
a Soviet defector by traveling inside his body.
Purdue scientists hope to use a similar fantastic-voyage
concept to create sensors that could alert us to any number of problems.
They would employ devices the size of bacteria to point out the
danger. In some cases, the devices might actually be genetically
modified bacteria or viruses that could serve as microbial watchdogs
that would travel through food, plants or livestock to alert us
to the presence of harmful substances.
"In agriculture, the potential is to have really
small, intelligent devices that can sense and interpret conditions
in the field," says Michael Ladisch,
Purdue distinguished professor of agricultural and biological engineering
and professor of biomedical engineering.
Ladisch predicts that, if developed, such devices
would change much of the way agriculture functions. Instead of waiting
for problems to arise and then addressing them, producers and food
processors would be alerted to problems as soon as they appear.
"Let's say, for example, that you have a target
organism, like foot-and-mouth disease. You might have these sensors
attached to the animals or to the facilities, and, if the sensors
detected the virus, they would alert you long before you'd see any
symptoms," Ladisch says. "Another agent that could be
detected this way would be the prions that cause mad cow disease."
Such sensors would rely on antibodies isolated from
infected animals. These antibodies would be put into devices, and
when the offending microbe or protein was present, it would match
up with the specific antibody, sending a signal.
According to Ladisch, these devices--about the size
of bacteria--would be small enough that one million of them would
fit in 10 milliliters or less of fluid. These would be small enough
and cheap enough to be sprayed on crops. "They might be coated
with some sort of substance that would allow them to stick to the
crops," Ladisch says. "Then, you could imagine someone
walking by with a handheld sensor, which would power the devices
through radio waves and receive the information."
Applegate is exploring different avenues to create
biosensors. There is a specific type of bacteria, for example, that
uses magnetic forces to orient itself in the world. By genetically
modifying these magnetotactic bacteria to interact with specific
contaminants, they could be detected with specialized equipment.
Applegate is working with scientists at the Naval Research Laboratory
to develop the technique to detect and quantify the magnetotactic
bacteria.
Applegate and Ladisch are also working together on
another idea that employs bacteriophages, which are viruses that
infect bacteria and resemble microscopic versions of the Apollo
lunar lander vehicles. These would then be detected using antibodies
using technology similar to home pregnancy tests.
"We could make these to detect food contaminants,
or even bioweapons such as anthrax or small pox," Applegate
says, pulling a small plastic home pregnancy test out of his desk.
"They would be cheap, disposable and more than 90 percent accurate."
A shrinking world inside
agriculture
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