ME biosensors show promise for pathogen detection on food surfaces
The surface-scanning coil detector excites and measures the resonant frequency of free-standing magnetoelastic (ME) biosensors that may be placed outside the solenoid coil boundaries.
Previously they had to be placed inside the coil before frequency measurement which limited their use to small objects or volumes that will fit within the coil, said Chai et al.
However, they found that the biosensor's frequency changes in a high humidity condition (95% RH).
ME biosensors demonstrated
Magnetoelastic (ME) biosensors consist of a transducer (ME resonator) that is coated with a bio-molecular recognition element for the capture and binding of pathogenic bacteria.
The coil measurement technique was demonstrated using an E2 phage-coated ME biosensor to detect Salmonella typhimurium on tomato surfaces.
Real-time, in-situ detection was achieved with a limit of detection (LOD) statistically determined to be lower than 1.5×103 CFU/mm2 with a confidence level of difference higher than 95% (p<0.05).
Salmonella and tomato test
A comparison study of the ME biosensor with polymerase chain reaction (PCR) and the plate culture method for detection of Salmonella on tomatoes was performed.
Salmonellawas grown on the tomatoes to mimic natural environmental conditions and results showed that the ME biosensor gave similar results to PCR and plate culture method with the ME biosensor being much faster, simpler and less costly than the PCR method.
ME biosensors placed directly on food surfaces for measurement can avoid time consuming and complex water wash procedures.
The researchers said the technique has benefits over enzyme-linking immunosorbent assay (ELISA) and PCR.
“First, the ME biosensor method uses phage as the bio-molecular recognition element. Phage has been shown to be highly robust and retain binding affinity even after high temperature storage and use in acid conditions. ME biosensors are wireless devices and require no on board power.”
Source: Biosensors and Bioelectronics volume 50, pages 311-317
Online ahead of print, doi: 10.1016/j.bios.2013.06.056
“A surface-scanning coil detector for real-time, in-situ detection of bacteria on fresh food surfaces “
Authors: Yating Chai, Shin Horikawa, Suiqiong Li, Howard C. Wikle, Bryan A. Chin
