title: Detection of Escherichia coli O157:H7 and Salmonella in ground beef by a bead-free quantum dot-facilitated isolation method.
abstract: The aims of this study were to introduce a new immunological bead-free cell detection method using quantum dots (QDs) as reporter markers for foodborne pathogen detection. QDs are nanosized particles with long-term photostability, high quantum yield, broad absorption spectra, and narrow, symmetric emission and high signal-to-noise ratio. The chemical compound [(1-ethyl-3-3-dimethylaminopropyl) carbodiimide hydrochloride] (EDC) and protein A were used as crosslinkers for manufacturing QD-antibody conjugates. To minimize the inhibition of QD fluorescence by the magnetic beads, the beads were removed after the primary pathogen isolation and before fluorescence measurement. Detection signals were increased four-fold after employing the bead-free isolation method. With a 24-h enrichment, the bead-free QD-facilitated detection method was able to detect 10 CFU/g Escherichia coli O157:H7 and Salmonella from artificially contaminated ground beef. To our knowledge, this detection method is the first research that combined a new EDC-protein A QD-labeling technique and bead-free fluorescence measurement to detect E. coli O157:H7 and Salmonella in ground beef.
authors.affiliation: Food Science Program, Division of Food Systems and Bioengineering, 256 WCS Wing, Eckles Hall, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Luxin
authors.initials: L
authors.lastname: Wang
authors.forename: Chung-Shieh
authors.initials: CS
authors.lastname: Wu
authors.forename: Xudong
authors.initials: X
authors.lastname: Fan
authors.forename: Azlin
authors.initials: A
authors.lastname: Mustapha
mesh_terms: D000818:Animals; D000906:Antibodies; D002234:Carbodiimides / Q000737:chemistry; D002417:Cattle; D004123:Dimethylamines / Q000737:chemistry; D004926:Escherichia coli; D019453:Escherichia coli O157 / Q000276:immunology / Q000302:isolation & purification*; D005453:Fluorescence; D005506:Food Contamination; D018189:Immunomagnetic Separation / Q000379:methods; D008460:Meat / Q000382:microbiology*; D045663:Quantum Dots; D012475:Salmonella / Q000276:immunology / Q000302:isolation & purification*; D059629:Signal-To-Noise Ratio
chemical_list: D000906:Antibodies; D002234:Carbodiimides; D004123:Dimethylamines; C569266:N-ethyl-N'-(3-(dimethylamino)-propyl)carbodiimide