NSTI Nanotech 2009

Fluorescent Silica Nano-Particles and Magnetic Bead Based Immunoassay: an Optical Tool for Detection of Staphylococcal enterotoxin B in Milk for High-Throughput Screening

S.K. Rastogi, J.R. Branen, S. Gibbon, A. Larry Branen
University of Idaho, US

Keywords: FSNPs, magnetic-bead immunoassay, SEB, milk

Abstract:

This paper describes the use of fluorescent silica nanoparticles (FSNPs) as luminescent signal amplifiers in biological system based on digital counting of individual particles and measuring of average fluorescence intensity, because FSNPs emit intense yellow-green luminescence upon excitation with an emission maximum at 535 nm of wavelength. A simple method was applied to prepare FSNPs (60, 100, and 850 5 nm) using a co-condensation of tetraethyl orthosilicate (TEOS) with trimethoxysisylpropyl-fluoroscien dye in water-in-oil (W/O) microemulsion method. The particles were characterized using SEM and TEM images for morphology characterization and dye distribution patterns and the FTIR spectroscopy for functional group characterization. The dye molecules are well protected in FSNPs from environmental oxygen and provide; high quality, and strong luminescent signal, excellent photo-stability, easy surface modification and size uniformity. The specific antibody was immobilized onto the FSNPs through silica chemistry. The staphylococcal enterotoxin B (SEB) initially captured from milk using a specific antibody bound to the magnetic bead. The magnetic bead complex was then reacted with the antibody-FSNPs. The significance of this method is that the SEB can be reliably and quickly detected in with detection limit of 25 50 pg/ml in milk samples
 
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