Fiber optic fluoro-immunosensor for detection of Salmonella based on evanescent wave absorption

In this study, the fiber optic fluoro-immunosensor was designed to detect Salmonella typhimurium positive control antigen. The fabricated system is consisted of the multimode optical fiber on which goat antiSalmonella was immobilized. And a sandwich assay is applied to the fabricated the fiber optic fluoro-immunosensor. In the ´sandwich´ binding format, a primary or ´capture´ antibody is immobilized on the core surface of the multimode optical fiber and a secondary or named as ´tracer´ antibody was added to the bulk solution. A tracer is that an antibody is labeled Fluorescein isothiocyanate (FITC: λ_ex=492 nm , λ_em=520 nm). Concentrations of 0.5, 1, 5, 10, 20, 30, 40 μg/ml Salmonella antigen were tested in different fibers. The detection limit of the manufactured system was 1 μg/ml, 0.5 μg/ml in nonlabeled monolayer phosphate buffered saline (NMP), nonlabeled monolayer carbonate bicarbonate buffer (NMC), respectively.