Oligopeptide Probe Coated Magnetoelastic Biosensors for the Rapid Detection of Salmonella Typhimurium

Magnetoelastic (ME) biosensors are composed of a resonating platform upon which molecular recognition probes are coated to capture and bind with a target species. Previously, we developed methods to isolate highly selective phage-displayed oligopeptide probes and immobilize them upon ME sensor platforms. These methods were used to isolate highly selective Salmonella enterica serovar Typhimurium probes that do not bind to other serovars of pathogenic Salmonella. The probes were tagged with Strep II tag before affinity immobilization upon a streptavidin coated ME sensor platform. The limits of detection were determined by testing over the range of 10² to 10⁶ cells and these ME biosensors were found to have greater sensitivity than other ME biosensors coated with E2 phage. The ME biosensors coated with oligopeptide probes were found to be highly selective for S. Typhimurium and did not react with S. Enteritidis, S. Newport, or E. coli O157:H7. These results demonstrate the efficacy of the ME biosensor method to detect S. Typhimurium and validate our approach to improve the sensitivity and selectivity of the sensor. The techniques developed in this work can be easily adapted for any foodborne or other agriculturally important bacterial pathogens.