Rapid detection of Cronobacter sakazakii in dairy food by biofunctionalized magnetic nanoparticle based on nuclear magnetic resonance

In order to ensure the safety of infant formula powder in China, a rapid and sensitive detection method for food-borne bacteria is urgently needed. We have developed a reliable immunoassay based on nuclear magnetic resonance for the specific detection of Enterobacter sakazakii in dairy samples with biofunctionalized magnetic nanoparticles. This method is able to detect Cronobacter sakazakii in milk powder and cheese samples at 1.1 to 11 MPN using the most-probable-number (MPN) assay, within an incubation period of less than 2 h. Longer incubation time (>4 h) or higher pH (>7) will decrease the sensitivity of this method. This method does not fit for the detection of bacteria at higher concentrations (>1100 MPN). This method has great potential to becomea useful tool for the rapid detection of bacterial contaminations in food, environmental and agricultural samples.