title: Evanescent wave fiber optic biosensor for salmonella detection in food.
abstract: Salmonella enterica is a major food-borne pathogen of world-wide concern. Sensitive and rapid detection methods to assess product safety before retail distribution are highly desirable. Since Salmonella is most commonly associated with poultry products, an evanescent wave fiber-optic assay was developed to detect Salmonella in shell egg and chicken breast and data were compared with a time-resolved fluorescence (TRF) assay. Anti-Salmonella polyclonal antibody was immobilized onto the surface of an optical fiber using biotin-avidin interactions to capture Salmonella. Alexa Fluor 647-conjugated antibody (MAb 2F-11) was used as the reporter. Detection occurred when an evanescent wave from a laser (635 nm) excited the Alexa Fluor and the fluorescence was measured by a laser-spectrofluorometer at 710 nm. The biosensor was specific for Salmonella and the limit of detection was established to be 10(3) cfu/mL in pure culture and 10(4) cfu/mL with egg and chicken breast samples when spiked with 10(2) cfu/mL after 2-6 h of enrichment. The results indicate that the performance of the fiber-optic sensor is comparable to TRF, and can be completed in less than 8 h, providing an alternative to the current detection methods.
authors.affiliation: Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, Indiana 47907, USA; E-Mails:  valadeza@gmail.com  (A.M.V);  mmorgan@purdue.edu  (M.T.M).
authors.forename: Angela M
authors.initials: AM
authors.lastname: Valadez
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Lana
authors.forename: Shu-I
authors.initials: SI
authors.lastname: Tu
authors.forename: Mark T
authors.initials: MT
authors.lastname: Morgan
authors.forename: Arun K
authors.initials: AK
authors.lastname: Bhunia