Magnetic focusing immunosensor for the detection of Salmonella typhimurium in foods

Philip E. Pivarnik; He Cao; Stephen V. Letcher; Arthur H. Pierson; Arthur Garth Rand

doi:10.1117/12.335777

12 January 1999 Magnetic focusing immunosensor for the detection of Salmonella typhimurium in foods

Philip E. Pivarnik, He Cao, Stephen V. Letcher, Arthur H. Pierson, Arthur Garth Rand

Proceedings Volume 3544, Pathogen Detection and Remediation for Safe Eating; (1999) https://doi.org/10.1117/12.335777
Event: Photonics East (ISAM, VVDC, IEMB), 1998, Boston, MA, United States

Abstract

From 1988 through 1992 Salmonellosis accounted for 27% of the total reported foodborne disease outbreaks and 57% of the outbreaks in which the pathogen was identified. The prevalence of Salmonellosis and the new requirements to monitor the organism as a marker in pathogen reduction programs will drive the need for rapid, on-site testing. A compact fiber optic fluorometer using a red diode laser as an excitation source and fiber probes for analyte detection has been constructed and used to measure Salmonella. The organisms were isolated with anti-Salmonella magnetic beads and were labeled with a secondary antibody conjugated to a red fluorescent dye. The response of the system was proportional to the concentration of Salmonella typhimurium from 3.2 X 10⁵ colony forming units (CFU)/ml to 1.6 X 10⁷ CFU/ml. The system was developed to utilize a fiber-optic magnetic focusing problem that attracted the magnetic microspheres to the surface of a sample chamber directly in front of the excitation and emission fibers. The signal obtained from a homogenous suspension of fluorescent magnetic microspheres was 9 to 10 picowatts. After focusing, the signal from the fluorescent labeled magnetic microspheres increased to 200 picowatts, approximately 20 times greater than the homogeneous suspension. The magnetic focusing assay detected 1.59 X 10⁵ colony forming units/ml of Salmonella typhimurium cultured in growth media. The process of magnetic focusing in front of the fibers has the potential to reduce the background fluorescence from unbound secondary antibodies, eliminating several rinsing steps, resulting in a simple rapid assay.

Citation Download Citation

Philip E. Pivarnik, He Cao, Stephen V. Letcher, Arthur H. Pierson, and Arthur Garth Rand "Magnetic focusing immunosensor for the detection of Salmonella typhimurium in foods", Proc. SPIE 3544, Pathogen Detection and Remediation for Safe Eating, (12 January 1999); https://doi.org/10.1117/12.335777

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