A new method using glycan-coated magnetic nanoparticles (gMNPs) is poised to change the way we detect foodborne pathogens like Escherichia coli and Salmonella in complex food matrices such as melons, lettuce, and raw chicken. Unlike traditional methods that rely on expensive antibodies or lengthy enrichment processes, this innovation offers a rapid detection system that extracts and confirms pathogens through qPCR in less than four hours. The gMNPs bind efficiently to pathogens, even in the presence of natural microbiota, across a wide range of pH levels and food matrices. At just $0.50 per test and without the need for cold storage, this approach has the potential to significantly reduce the global burden of foodborne illnesses.
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.
Published (DOI: 10.1093/fqsafe/fyaf007) on February 19, 2025, in Food Quality and Safety , 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.
