title: Detect of Escherichia coli O157:H7 in ground beef samples using piezoelectric excited millimeter-sized cantilever (PEMC) sensors.
abstract: Piezoelectric-excited millimeter-sized cantilever (PEMC) sensors consisting of a piezoelectric and a borosilicate glass layer with a sensing area of 4 mm2 were fabricated. An antibody specific to Escherichia coli (anti-E. coli) O157:H7 was immobilized on PEMC sensors, and exposed to samples containing E. coli O157:H7 (EC) prepared in various matrices: (1) broth, broth plus raw ground beef, and broth plus sterile ground beef without inoculation of E. coli O157:H7 served as controls, (2) 100 mL of broth inoculated with 25 EC cells, (3) 100 mL of broth containing 25 g of raw ground beef and (4) 100 mL of broth with 25 g of sterile ground beef inoculated with 25 EC cells. The total resonant frequency change obtained for the broth plus EC samples were 16+/-2 Hz (n=2), 30 Hz (n=1), and 54+/-2 Hz (n=2) corresponding to 2, 4, and 6h growth at 37 degrees C, respectively. The response to the broth plus 25 g of sterile ground beef plus EC cells were 21+/-2 Hz (n=2), 37 Hz (n=1), and 70+/-2 Hz (n=2) corresponding to 2, 4, and 6 h, respectively. In all cases, the three different control samples yielded a frequency change of 0+/-2 Hz (n=6). The E. coli O157:H7 concentration in each broth and beef samples was determined by both plating and by pathogen modeling program. The results indicate that the PEMC sensor detects E. coli O157:H7 reliably at 50-100 cells/mL with a 3 mL sample.
authors.affiliation: Department of Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, United States.
authors.forename: Gossett A
authors.initials: GA
authors.lastname: Campbell
authors.forename: Joe
authors.initials: J
authors.lastname: Uknalis
authors.forename: Shu-I
authors.initials: SI
authors.lastname: Tu
authors.forename: Raj
authors.initials: R
authors.lastname: Mutharasan
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation*; D002417:Cattle; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005516:Food Microbiology; D008460:Meat / Q000382:microbiology*