Nanotech-Based Biosensor Can Detect Listeria in Food

A nano-biosensor capable of detecting Listeria monocytogenes in food has been developed by researchers in Maine. The assay detected L. monocytogenes artificially inoculated on wild blueberries with specificity over other pathogens, the researchers reported.

“The biosensor we developed has great potential to ensure food safety,” said Vivian Wu, PhD, an associate professor of microbiology and food safety at the University of Maine in Orono. “Currently it is designed for detecting L. monocytogenes, but the technology could be further modified to target other important foodborne and waterborne pathogens and toxins.”

Dr. Wu is senior author of a report in Industrial Biotechnology describing the technology, which is based on screen-printed carbon electrode (SPCE) strips similar to those used by diabetic patients for blood glucose monitoring. The strips, modified by the addition of gold nanoparticles, are capable of detecting L. monocytogenes at 2 log CFU/g in wild blueberry samples. They can detect a single bacterial cell in as little as one hour, the researchers reported.

“This biosensor is inexpensive and portable, so it would be extremely beneficial for on-site screening tests conducted by the food industry and regulatory agencies,” Dr. Wu said in an email to Food Quality. “This will save a lot of time when compared to traditional methods. Perhaps, one day, it could be used by consumers at home once is it further optimized and commercialized, just like the glucose monitoring strips used by diabetic patients daily.”

Daniel Y.C. Fung, MSPH, PhD, a professor of food science and animal sciences at Kansas State University in Manhattan, Kan., is familiar with Dr. Wu’s research, although he was not himself involved in the work. He said the use of nanotechnology for rapid detection of pathogens is a field that is progressing quickly.

“I think nanotechnology has a lot of potential in this area,” Dr. Fung said in an interview. “The field is developing very fast for detecting individual organisms rapidly, such as in this case L. monocytogenes. If you had a panel of these types of detectors, you could detect many organisms individually. In the long run, we may see the development of multiplexing, where you can detect multiple organisms at the same time. Right now, these technologies are becoming very good at detecting specific organisms.”