Foodborne pathogens such as Salmonella and E. coli are responsible for an estimated 600 million illnesses annually. Existing detection methods often rely on slow, overnight enrichment or costly antibody-based tools. Traditional techniques such as centrifugation and filtration face challenges like clogging, while immunomagnetic separation (IMS) struggles with fat-rich foods and high costs. While alternatives like amine-functionalized nanoparticles are available, they are time-consuming to prepare. Carbohydrate-coated nanoparticles have offered stability and affordability, but they have yet to be validated for diverse solid food matrices. This creates a pressing need for rapid, scalable solutions capable of detecting low concentrations of pathogens—essential for preventing outbreaks.
on March 25, 2025, in , a study by scientists at Michigan State University presents a novel glycan-coated magnetic nanoparticle (gMNP) system. This system extracts and concentrates E. coli and Salmonella from foods in less than four hours. The one-pot-synthesized nanoparticles are stable at room temperature and bind pathogens site-specifically, enabling detection via qPCR without the need for prior enrichment. Tested in melons, cucumbers, chicken, and lettuce, the method achieved concentration factors up to 5.8, surpassing traditional IMS techniques in both cost ($0.50 per sample) and speed.
The innovation of this study lies in the dual advantages of gMNPs: simplicity and versatility. The nanoparticles, synthesized in a single step, bind pathogens across a pH range of 3–9. Key findings include an 80% capture rate for E. coli and 20% for Salmonella Enteritidis in phosphate-buffered saline (PBS), with even higher yields in acidic conditions. Despite the presence of competing microbiota, Salmonella concentrations reached 5.8 times higher in melons, and E. coli showed superior performance in chicken (CF 2.8). Confocal microscopy confirmed that the nanoparticles bind specifically to the bacterial edges, ensuring accurate pathogen capture. The system significantly reduces detection time to less than four hours by eliminating the need for enrichment. qPCR validation showed lower Cq ratios, indicating enhanced sensitivity. Importantly, the gMNP method overcomes the limitations of IMS, including the need for cold storage and antibody interference, while being capable of handling larger sample volumes (up to 100 mL). However, challenges like variable capture factors in protein-rich foods suggest potential biofilm interactions that may require future optimization.
Dr. Evangelyn Alocilja, the study's lead author, emphasized the importance of this platform in revolutionizing food safety: "By replacing antibodies with glycan coatings, we've dramatically reduced costs and storage demands while maintaining high sensitivity. The ability to detect 100 CFU/mL directly in lettuce or chicken without enrichment is a paradigm shift for the industry." An independent food safety expert further commented, "The scalability and compatibility with qPCR make gMNPs a game-changer, offering a viable solution for both the food industry and low-resource settings."
The gMNP-qPCR system holds immense potential for rapid screening of perishable goods during transit, quicker outbreak traceability, and affordable testing in regions lacking laboratory infrastructure. Future advancements could include the automation of pathogen extraction for high-throughput testing and the expansion of pathogen targets. With 420,000 deaths linked to foodborne pathogens each year, the adoption of this technology could help meet the World Health Organization's goals for safer food systems, potentially reducing food recalls and hospitalizations worldwide.
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This research was supported by the Targeted Support Grant for Technology Development (TSGTD), Michigan State University Foundation, USA; the USDA Hatch project MICL 02782, USDA Hatch Multistate NC1194 MICL 04233, and the USDA-NIFA project 2022-67017-36982,.
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(FQS) is an open access, international, peer-reviewed journal providing a platform to highlight emerging and innovative science and technology in the agro-food field, publishing up-to-date research in the areas of food quality, food safety, food nutrition and human health. It is covered by SCI-E and the 2023 Impact Factor (IF)=3.0, 5-yr IF=4.7.
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