Rapid and sensitive biosensor for Salmonella

The rapid and sensitive detection of Salmonella typhymurium based on the use of a polyclonal antibody immobilized by the Langmuir–Blodgett method on the surface of a quartz crystal acoustic wave device was demonstrated. The binding of bacteria to the surface changed the crystal resonance parameters; these were quantified by the output voltage of the sensor instrumentation. The sensor had a lower detection limit of a few hundred cells:ml, and a response time of B100 s over the range of 102–1010 cells:ml. The sensor response was linear between bacterial concentrations of 102–107 cells:ml, with a sensitivity of 18 mV:decade. The binding of bacteria was specific with two binding sites needed to bind a single cell. The sensors preserve 75 % of their sensitivity over a period of 32 days. © 2000 Elsevier Science S.A. All rights reserved