Analytical chemistry | 19 Dec 2012
AV Orlov, JA Khodakova, MP Nikitin, AO Shepelyakovskaya, FA Brovko, AG Laman, EV Grishin and PI Nikitin
Method of highly sensitive registration of magnetic nanoparticles by their non-linear magnetization is used in a novel sandwich-type immunoassay for detection of staphylococcal toxins in complex media of virtually any volume, with increasing sensitivity at higher sample volume. The signal is read out from the entire volume of a non-transparent 3D fiber structure employed as a solid phase, which provides large reaction surface, quick reagent mixing as well as antigen immunofiltration directly in the course of the assay. The method has demonstrated near-linear dose-response curves within wide range of ~3 decades while detection of staphylococcal enterotoxin A (SEA) and toxic shock syndrome toxin (TSST) in neat milk without sample preparation. The limits of detection (LOD) as low as 4 and 10 pg/mL for TSST and SEA, respectively, were obtained in 2-hour format using 30-mL samples. The second, 25-minute format, showed the LOD of 0.1 and 0.3 ng/mL for the same toxins in a 150 µL sample. The developed immunoassay can be applied in food safety control, in vitro diagnostics and veterinary for a variety of research from express tests in the field to highly sensitive laboratory tests.
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