Rapid detection of Salmonella enteritidis and Escherichia coli using surface plasmon resonance biosensor

The Biacore surface plasmon resonance (SPR)-based biosensor was used to detect Salmonella enterica serovar Enteritidis and Escherichia coli in spiked skim milk using specific antibodies. The optical SPR biosensor registers changes in the refractive index during binding of the analyte (bacteria) to the ligand (antibody) on the gold-coated sensor chip surface. Immobilized protein A-captured specific antibodies were used to detect the bacteria in less than an hour. The reaction was found to be specific, and the limits of detection of the assay were found to be 25 cfu/mL for E. coli and 23 cfu/mL for Salmonella. Because the assays were shown to be sensitive, reproducible and very specific, the SPR-based Biacore biosensor has the potential for near real-time, yet specific, detection and presumptive identification of bacteria in food and water.