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

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