Magnetic Immunoassay for Detection of Staphylococcal Toxins in Complex Media

Abstract

Method of highly sensitive registration of magnetic nanoparticles by their nonlinear 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 nontransparent 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 a 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-h format using 30-mL samples. The second, 25-min 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.

Biosensors based on spectral correlation interferometry for biomedical research and diagnostics

“…The MP are very attractive nanolabels for biosensors [2]. Such application required knowledge of recognition properties of antibodies (AB) immobilized on MP surface.…”

Metal nanoparticles as a new type of labels in rapid immunoassay methods

“…An analytical method for highly sensitive quantification of staphylococcal tox ins in food has been designed based on such a system using magnetic nanoparticles [51].…”

Recent Developments in Antibody-Based Assays for the Detection of Bacterial Toxins

“…, 100 zeptomoles or 100,000 molecules of CT in a sample volume of 0.1 mL. Furthermore, nonlinear magnetization of MNPs has been used for a novel sandwich immunoassay on a 3D fiber solid phase for the detection of Staphylococcal Enterotoxin A (SEA) and TSST in milk samples [53]. This label-free assay achieves a limit of detection as low as 4 pg mL −1 and 20 pg mL − 1 for TSST and SEA, respectively.…”