Magnetic nanocomposites: versatile tool for the combination of immunomagnetic separation with flow-based chemiluminescence immunochip for rapid biosensing of Staphylococcal enterotoxin B in milk.

Abstract

Immunomagnetic separation (IMS) was combined with flow-based chemiluminescence sandwich immunoassays (CL-SIA) for the quantification of Staphylococcal enterotoxin B in milk. Therefore, iron oxide-shell silica-core magnetic nanocomposites were conjugated to biotinylated anti-SEB antibodies (MNC-IgGs). MNC-IgGs were applied successfully for (i) capturing SEB in milk samples by an affinity reaction, (ii) magnetophoretic collection on antibody spots in a channel of a flow-based immunochip, and (iii) sensitive enzymatic chemiluminescence detection of biotin labels by poly(horseradish peroxidase)-streptavidin. IMS was performed in 0.6mL and 100mL milk samples resulting in detection limits of 50ngL-1 and 0.39ngL-1, respectively, for the combined analytical method. It was shown that the assay sensitivity was dramatically improved by the combination of IMS with flow-based CL-SIA compared to CL-SIA directly applied with milk samples (detection limit 130ngL-1). The IMS-CL-SIA has a time-to-result of 2-3h. The reported combined analytical method can be used for a rapid control of SEB in complex food matrices such as milk. In future, even the monitoring of multiple contaminants in food or water may be performed by IMS-CL-SIA. Graphical abstract.