Analytical Sciences

Escherichia coli O157:H7 Detection Limit of Millimeter-Sized PZT Cantilever Sensors is 700 Cells/mL

Gossett A. CAMPBELL and Raj MUTHARASAN

Department of Chemical Engineering, Drexel University, Philadelphia, PA 19104, USA

A composite self-excited millimeter-sized lead zirconate titanate (PZT) glass cantilever (2 mm × 1.8 mm; sensing area of 6 mm²) was fabricated for the detection of Escherichia coli (E. coli) O157:H7. The fundamental and second mode resonance in air was 10.95 ± 0.05 kHz and 43.45 ± 0.05 kHz, respectively. Affinity purified monoclonal antibody (anti-E. coli O157:H7) specific to the pathogen E. coli O157:H7 was immobilized at the cantilever glass tip, and then immersed in liquid containing the pathogen (70 to 7 × 10⁷ cells/mL). The resonant frequency showed a reduction and reached a steady state shift of 0 ± 5, 46 ± 5, 260 ± 5, and 1010 ± 5 Hz corresponding to 0, 700, 7000, and 7 × 10⁷ cells/mL. From the experiments conducted, the detection limit of the sensor was 700 cells/mL.

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