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Piezoelectric-Excited Millimeter Sized Cantilever (PEMC) Sensors for Highly Sensitive and Rapid Detection of Group a Streptococcus and Listeria Monocytogenes In Practical Matrixes

Harsh Sharma and Raj Mutharasan. Chemical and Biological Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104

The purpose of this study is to establish the feasibility of direct detection of infectious agents in practical matrixes (human serum for Group A Streptococcus [GAS] and chicken-wash for Listeria monocytogenes [LM]) and to determine the limit of detection for these antigen-matrix systems. We describe a biosensor-based approach for detection of the two infectious agents in practical matrixes in 15-20 min. The electrically-excited and electrically-sensed PEMC sensors show resonant frequency decrease as antigen binds to it. After immobilizing antibody to specific target pathogen, the sensor was exposed to test sample containing known concentrations of GAS or LM. Concentrations as low as 10 pathogens per ml show a decrease in resonant frequency of ~500 Hz while noise in measurement is ~30 Hz. Because the sensors were shown in our earlier work to exhibit mass-change sensitivity of a few femtograms, it is feasible to detect at concentrations as low as one pathogen per ml. Current experiments at low concentrations will be described.