Simultaneous Detection of Salmonella typhimurium and Bacillus anthracis Spores Using Phage-Based Magnetoelastic Biosensors

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Deliberate contamination of the food supply has become a concern, Salmonella typhimurium and Bacillus anthracis spores being primary pathogens of interest. The objective of this research was to investigate simultaneous detection of these two biological pathogens using one type of sensor. The biosensors investigated are comprised of a magnetoelastic particle coated with phage as the biomolecular recognition element. An AC magnetic field is used to resonate the magnetoelastic particle. As bacteria/spores are captured by the phage, the mass of the sensor increases, which results in a decrease in the sensor’s resonant frequency. Two genetically engineered phages, binding with Salmonella typhimurium or Bacillus anthracis, were immobilized onto two separate magnetoelastic particles with different dimensions, allowing simultaneous measurement of two different resonance peaks. An analyte containing known concentrations of each target pathogen was passed through the system. Only the biosensor coated with the corresponding phage responded. The performances of the biosensors, including specificity, sensitivity, and response time, are reported. Microscopy techniques (TEM/SEM) were used to verify and quantify interaction of bacteria/spores with the corresponding phage on each biosensor. Results show that the measured number of bound bacteria/spores corresponds closely to the theoretically calculated number of bound bacteria/spores obtained from frequency shifts.

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Journal: TechConnect Briefs
Volume: 2, Technical Proceedings of the 2007 NSTI Nanotechnology Conference and Trade Show, Volume 2
Published: May 20, 2007
Pages: 515 - 518
Industry sector: Sensors, MEMS, Electronics
Topicss: Biomaterials, Chemical, Physical & Bio-Sensors
ISBN: 1-4200-6183-6