MEMS: From Micro Devices to Wireless Systems

Vol. 7, Special Issue, October 2009, pp.191-202

Magnetic Bead and Fluorescent Silica Nanoparticles Based Optical Immunodetection
of Staphylococcal Enterotoxin B (SEB) in Bottled Water

Shiva K. RASTOGI, Veronica J. HENDRICKS, Josh R. BRANEN
and A. Larry BRANEN

Biosensors and Nanotechnology Application Laboratory, University of Idaho,
721 Lochsa Str. Ste. 3, Post Falls, ID-83854, USA

Tel.: 1-208-262-2019, 1-208-777-2407

E-mail: srastogi@uidaho.edu

Received: 28 August 2009   /Accepted: 28 September 2009   /Published: 12 October 2009

Abstract: Staphylococcal enterotoxins (SEs) are a major cause of food-borne diseases, most commonly SEs assayed immunologically with ELISA. An immunoassay based on fluorescein dye doped silica dioxide nanoparticles (F-SiNPs) and magnetic bead (MB) is described here for the detection of staphylococcal enterotoxin B (SEB). F-SiNPs have unique optical properties which make them attractive for biosensing. The water-in-oil (W/O) reverse microemulsion method was used for the synthesis of F-SiNPs (~ 95 nm of diameter). The F-SiNPs were characterized using SEM, TEM and FTIR spectroscopy. The detection of SEB is preformed in PBS buffer, and bottled drinking water using sandwich immunoassay format. Target analytes were captured using MBs modified with the antigen-specific “capture” antibody, and detected using F-SiNP labeled secondary antigen-specific antibody. We report a limit of detection down to 1 ng/mL SEB spiked sample in less than 2 hr assay time using fluorocount method. This study demonstrates the bio warfare agent SEB capture by magnetic beads and detection using F-SiNPs.

Keywords: Fluorescein dye, Silica dioxide nanoparticles, Magnetic beads, Sandwich immunoassay, Toxin biosensor

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