Biomolecule-functionalized magnetic nanoparticles for flow-through quartz crystal microbalance immunoassay of aflatoxin B1

Abstract

A flow-through quartz crystal microbalance (QCM) immunoassay method has been developed based on aflatoxin B₁ antibody (anti-AFB₁)-functionalized magnetic core-shell Fe₃O₄/SiO₂ composite nanoparticles (bionanoparticles) in this study. To construct such an assay protocol, anti-AFB₁, as a model protein, was initially covalently immobilized onto the Fe₃O₄/SiO₂ surface, and then the functionalized nanoparticles were attached to the surface of the QCM probe with an external magnet. The binding of target molecules onto the immobilized antibodies decreased the sensor’s resonant frequency, and the frequency shift was proportional to the AFB₁ concentration in the range of 0.3–7.0 ng/ml. The regeneration of the developed immunosensor was carried out via attaching or detaching the external magnet from the detection cell. In addition, the selectivity, reproducibility, and stability of the proposed immunoassay system were acceptable. Compared with the conventional ELISAs, the proposed immunoassay system was simple and rapid without multiple labeling and separation steps. Importantly, the proposed immunoassay method could be further developed for the immobilization of other antigens or biocompounds.