Rapid and sensitive biosensor for Salmonella

The rapid and sensitive detection of Salmonella typhymurium based on the us e of a polyclonal antibody immobilized by the Langmuir-Blodgett method on t he surface of a quartz crystal acoustic wave device was demonstrated. The b inding 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 re sponse time of < 100 s over the range of 10(2)-10(10) cells/ml. The sensor response was linear between bacterial concentrations of 10(2)-10(7) cells/m l, 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 similar to 75% of their sensitivity over a period of 32 days. (C) 2000 Else vier Science S.A. All rights reserved.