Detection of pathogen Escherichia coli O157:H7 using self-excited PZT-glass microcantilevers

Composite self-excited PZT-glass cantilevers (5 and 3 mm in length, 1.8 and 2.0 mm wide) were fabricated and their resonance characteristics were determined in air and at 1 mm liquid immersion. In air, resonance occurred at 65.8 and 63.4 kHz for the two cantilevers used in this paper. Monoclonal antibody (MAb) specific to the pathogen Escherichia coli ( E. coli) O157:H7 was immobilized at the cantilever glass tip, and then exposed to pathogen in the concentration range of 7 × 10 2 to 7 × 10 7 bacteria/mL. Resonance of the second mode decreased due to pathogen attachment in accordance with a proposed kinetic model. The specific attachment rate constant was found to be 3 × 10 −9 to 5 × 10 −9 min −1 (cell/mL) −1. Exposure to a mixed population containing both a pathogenic and non-pathogenic strain showed that the antibody-immobilized cantilever is highly selective, thus demonstrating its usefulness for detecting water-borne pathogens.