By using live cells, called biosensors, this technology can identify actively harmful pathogens but ignore those that are inactive, or harmless. Some analogous tests lack this capability, making them prone to false alarms and entailing a relatively lengthy incubation period to grow out any living microbes, Banerjee said. The new technology's discerning power also could help optimize processes to kill harmful microbes or deactivate toxins, he said.
Another advantage to the technique is its mobility and versatility, Bhunia said. The multi-well plates and their contents of gel-suspended mammalian cells could be efficiently prepared in a central location. When desired, the plates could then be shipped to the test location, like a food processing plant, so that analysis could take place on-site, he said.
This technology tests for bacteria and toxins that attack cell membranes. For this reason, researchers employed cells with high amounts of alkaline phosphatase, the signaling chemical released upon damage to the cell membrane. Researchers could conceivably employ other types of cells within this framework to detect additional types of pathogens, Bhunia said.
Samples of food and water are added to biosensor wells before being incubated for one to two hours. To each well a chemical is added that reacts with the biosensor's alkaline phosphatase, yielding a yellow product quantified by a special camera and a computer. A precise calculation may be unnecessary sometimes, however.
"When a large amount of pathogen is present, you can literally see the color change taking place before your eyes," Banerjee said.
The suspension of live mammalian cells within a collagen gel is unique, according to the researchers.
"This is the first time that anybody has trapped these kinds of cells alive in a collagen framework," Bhunia said.
Researchers are trying to get these cells to live within t
|Contact: Douglas M. Main|