Nanosensors may create easy and cost effective methods to detect disease in cattle.
These tiny sensors use the properties of nanoparticles to detect changes in the environment. Some nanoparticles, for example, conduct small amounts of electricity when exposed to certain chemicals and could possibly be tuned to do so on contact with fertilizers and pesticides. Other nanoparticles may be designed to react to bacteria, disease or environmental conditions such as light and humidity.
“You look at one compound, you know you have a certain material it will react to, and through nanotech you find a way to optimize that response through roughness and composition and so on,” said Stéphane Evoy, principal investigator for devices and sensors at the National Institute of Nanotechnology in Edmonton.
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A small film, about a millimetre square and made up of nanoparticles, would be used to do the sensing, Evoy said. The particles’ reaction to environmental conditions would be transmitted to an electronic device, which Evoy estimates would be about the size of a cell phone. It could transmit the information to a computer.
“If you want to have something that communicates wirelessly, 90 percent of the volume of the box will be about that.”
The main difficulties that must be overcome in this field have nothing to do with nanosensors.
With the technology now available to create these detecting particles, the primary hurdles are to bring down costs and develop power sources that last a long time.
Hongda Chen, national program leader for bioprocessing and nanotechnology with the U.S. Department of Agriculture, said nanosensors are high on the department’s to-do list.
“Within this program area, we have four priorities, as it stands now, and the first one is the development of detection and intervention technology to assure food safety and agricultural biosecurity,” Chen said.
Because the sensors are so small they would be able to detect minute traces of bacteria such as E. coli, and possibly the prions thought to cause BSE.
“The rule of thumb is that the best sensor is at the size of your target,” Chen said.
“If you look at the detection of pathogenic bacteria … the best sensor is probably the size of the bacteria.”
Testing for bacteria is now done using a method known as enrichment. Animal tissue is placed in a petri dish that has been prepared to foster the growth of bacteria such as E. coli or listeria.
“The traditional method is that you take a sample, you enrich it and then you separate them, and for each bug you have a specific (test) … so that adds even more time for detection,” Chen said.
Live testing
In addition to making the test faster, it may be possible to use nanosensors for on-site testing for BSE. Instead of killing the animal and sending its brain away for BSE testing, inspectors may one day be able to wave a scanner over suspicious cattle.
A hand held device could test for several things at once.
“With very small devices, you take a drop of water or a drop of food, a sample, and you can do all these tests, and because of the small size you can put multiple sensors or sensing mechanisms in a very small (device),” Chen said.
