Food-borne pathogenic bacteria like Salmonella, Listeria and Yersinia are responsible for thousands of deaths each year-and no small amount of anxiety in a society that imports food from across the globe.
Five UGA scientists, including one graduate student, are part of an international team that has developed a promising nanotechnology-based biosensor to detect these critical breakdowns in food safety and public health. The new method uses a silicon/gold nanorod array to produce an enhanced fluorescence screening procedure, marking important new benchmarks in detection speed and sensitivity.
In experiments published in the March 11 online edition of Nanotechnology, nanorod arrays were fitted with anti-Salmonella antibodies and dye molecules. Once these antibodies were captured by the bacteria, the nanorods emitted strong and easily detectable fluorescence under blue laser excitation. Where traditional, microbiological techniques can take up to five days to obtain a positive result, the single component nanostructures were designed to generate dependable signals almost immediately.
“Nanostructures have two very potent characteristics that are showing promise in biosensor applications,” said Yiping Zhao, associate professor in the department of physics and astronomy and a member of the UGA research team. “They can be designed with certain recognition mechanisms specified to particular antibodies or enzymes. And their distinguishing signal can be generated by molecules embedded in the nanostructures themselves.”
Junxue Fu, a graduate student in Zhao’s group, is the paper’s first author and conducted the major experiments. The research team included Ralph A. Tripp and Les Jones of UGA’s department of infectious diseases, Bosoon Park, UGA adjunct engineering professor who is also with the U.S. Department of Agriculture and a scientist from the Korea Food Research Institute.
The procedure employs hetero-nanostructures, with components made up of differing functional molecules to reach greater selectivity and specificity in the detection of bacteria.
In their experiments, Zhao, Park, Tripp and their colleagues were able to capture a single Salmonella bacterium with antibodies attached to the gold and detected by thousands of dye molecules immobilized on the silicon nanorods. The hetero-structured nanorod arrays were fabricated using the glancing angle deposition and sputtering growth techniques. Members of the group have been working on advanced nanotechnology fabrication techniques for a variety of applications, bringing a depth of disciplines and expertise to multi-faceted issues like food safety.
“The ability to detect threats like pathogenic bacteria in food or drinking water is crucial to protecting public health,” said Tripp, a Georgia Research Alliance Eminent Scholar who was formerly a researcher at the national Centers for Disease Control.
“The findings in the paper represent a foundational and enabling technology that bridges nanotechnology with microbiology to meet the rapid operational demands of our food processing and distribution systems.”