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 7x10(2) to 7x10(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 3x10(-9) to 5x10(-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.