Newswise — Food processors have ways to rapidly detect whether their products have any pathogenic bacteria on them. The problem is that the definition of "rapid" can mean a matter of hours. Yanbin Li's research team at the University of Arkansas Division of Agriculture is closing in on a way to reduce that to minutes " one hour at most.
The key is the immunosensor. Li, a biological and agricultural engineering professor who leads the project for the Food Safety Consortium, said the team has modified some existing technology with immunosensors to target foodborne bacteria quickly.
Immunosensors are compact analytical devices that use antibodies (protein substances produced in tissues) to produce a digital electronic signal that scientists use to determine if a particular pathogen is present. The deadly E. coli O157:H7 pathogen has been one target of Li's research.
"We make the sensor very specific and very sensitive," Li said. "We use electrochemical sensing technology. We measure the electrical current. The magnitude of the current is proportional to the cell number of target bacteria. That way we link the electronic signal to the biological signal."
To apply the procedure to foodborne pathogens, Li's group turned its attention to a couple of available technologies used in immunosensors: QCM (quartz crystal microbalance) and SPR (surface plasmon resonance). The QCM technology measures small amounts of particles on an electrode's surface based on its mass, while SPR accomplishes the task based on an optical sensor.
"We have those technologies in the equipment, but they are not designed for the detection of bacteria," Li explained. "They are basically designed for detecting some particular chemical compounds or small molecules substances."
Li's group developed its own protocol to integrate the technology into their immunosensors for biodetection. "We can modify this technology to be able to detect the pathogenic bacteria."
Detecting biological signals and comparing them to electronic signals is difficult because the researchers are looking for ultralow concentrations of bacteria in a sample (fewer than 10 cells per milliliter). Li's group determined that both QCM and SPR immunosensors are capable of finding their target bacteria in an hour. The research group is attempting to adapt other technologies, including nanomaterials and microfluidics, to biosensor design and is seeking to improve a final product's sensitivity to finding the bacteria.
The experiments were geared toward the detection of E. coli O157:H7, but it can be applied to other pathogens on a variety of foods. "This technology should be ready for any other pathogenic bacteria and for any meats and vegetables," Li said.
Li hopes to develop the technology further based on their five pending patents and to work with industry for transfer of the technology to commercial use in the next two to three years.
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