The effect of incubation time for Salmonella Typhimurium binding to phage-based magnetoelastic biosensors

This study presents an investigation of the effect of incubation time on the binding of Salmonella Typhimurium (Salmonella) with E2 phage-based magnetoelastic (ME) biosensors. After inoculation of Salmonella on a tomato surface, the attachment and existence of Salmonella on the tomato surface was observed using scanning electron microscopy (SEM). Measurement sensors with immobilized E2 phage and control sensors devoid of phage were placed on the inoculated tomato surface and incubated for various times. The extent of binding of Salmonella to the ME biosensors was determined by measuring the resonant frequency shift of the sensors and confirmed by SEM. The attachment of Salmonella on the tomato surface increased as the inoculation concentration increased. Significant increases in the frequency shifts for the measurement sensors were observed between 15 and 30 min (P < 0.001), exhibiting 3439 ± 185 and 5312 ± 248 Hz, respectively. Further incubation times did not increase Salmonella binding with E2 phage whereas longer incubation times increased non-specific attachment from residual nutrients on the tomato surface. In contrast, there was either no or negligible binding of Salmonella on the control sensors. This study will contribute to the development of a practical protocol for the ME biosensor method.