Salmonella Typhimurium Detection on Fresh Food Surfaces Using a Surface-Scanning Coil Detector and Magnetoelastic Sensors

This study presents results from an investigation into the rapid, sensitive, real-time direct detection of Salmonella Typhimurium on food surfaces. The biosensor consists of a freestanding, strip-shaped magnetoelastic (ME) resonator as the signal transducer and E2 phage as the bio-molecular recognition element that selectively binds with S. Typhimurium (1). The ME resonator is a class of mass-sensitive biosensor that can be wirelessly actuated into mechanical resonance by an externally applied time-varying magnetic field (2). When the biosensor binds with S. Typhimurium, the mass of the sensor increases, resulting in a decrease in the sensor's resonant frequency (3). We have previously reported the possible use of ME biosensors for the detection of pathogenic bacteria on food surfaces (4). This new detection system consists of a planar spiral coil that excites and measures the resonant frequency of freestanding ME biosensors on the surface of fruits and vegetables (5). Multiple E2 phage-coated biosensors (measurement sensors) were placed on the food surfaces spiked with S. Typhimurium of various concentrations. Control sensors without phage were also used to compensate for environmental effects and non-specific binding. During binding with the bacteria, the resonant frequency of the sensor was wirelessly measured in real time.  This frequency change is directly proportional to the mass of the bacteria bound to the sensor surface.  

References

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