Development of Surface Plasmon Resonance-Based Immunoassay for Aflatoxin B₁

Abstract

Aflatoxins are a group of highly toxic fungal secondary metabolites that occur in Aspergillus species and may contaminate foodstuffs and feeds. Two different anti-aflatoxin B(1) antibodies were examined to develop a surface plasmon resonance (SPR)-based immunoassay to aflatoxin B(1). A conjugate consisting of aflatoxin B(1)-bovine serum albumin (BSA) was immobilized on the dextran gel surface. Competition between immobilized aflatoxin B(1) conjugate and free aflatoxin B(1) in solution for binding to antibody injected over the surface formed the basis for the assay. Regeneration of the antibody from the immobilized conjugate surface is essential for the development of such an inhibitive immunoassay. Problems were encountered with the regeneration of the sensor surface, due to the high-affinity binding of the antibodies. Conventional regeneration solutions consisting of low concentrations of NaOH and HCl worked to a degree, but regeneration was at the expense of the integrity of the immobilized conjugate. A polyclonal anti-aflatoxin B(1) antibody was produced and was found to be regenerable using an organic solution consisting of 1 M ethanolamine with 20% (v/v) acetonitrile, pH 12.0. This combined high ionic strength and extreme pH, as well as chaotrophic properties and allowed the development of an inhibitive immunoassay. The assay had a linear range of 3.0-98.0 ng mL(-1) with good reproducibility.

Aptamer based surface plasmon resonance sensor for aflatoxin B1

“…It is relatively challenging to develop SPR sensors for small [27], inhibition [28] or sandwich strategies [29]. Dary et al [30] described a SPR-based immunoassay to the detection of AFB1 using an indirect competitive sensing method. A conjugate consisting of AFB1-bovine serum albumin (AFB1-BSA) was attached on sensor chip.…”

Sensitive detection of aflatoxin B1 molecules on gold SPR chip surface using functionalized gold nanoparticles

“…Some research groups focus on the rapid and simple detection from maize grift samples. The usual methods in AFB1 detection include HPLC, immunoassay and SPR methods (Daly et al 2000;Li and Zhang 2009;Moricz et al 2007). Urusov et al (2014a) describe a sensitive method for the immunochromatographic determination of aflatoxin B1.…”

“…Although numerous procedures can detect and determine the aflatoxin derivatives, the most typical one is the time-delayed analysis of aflatoxin derivatives by thin-layer chromatography, high-performance liquid chromatography, overpressuredlayer chromatography, and enzyme-linked immunosorbent assay (Li and Zhang 2009;Manetta et al 2005;Moricz et al 2007;Peiwu et al 2009;Urusov et al 2014b;Var et al 2007). The detection of mycotoxins by SPR from food-stuff has already been reported in several publications and those with low molecular weight (aflatoxin, ochratoxin A) were determined by SPR immunosensors (Daly et al 2000;Hodnik and Anderluh 2009;Homola 2008;Li et al 2012;Yuan et al 2009). The guest molecules (AFB1) interact with the cavity of the host molecule with non-covalent forces (Szejtli 2004).…”

“…4). The absorbed quantities in the function of the concentration are presented in Fig 4. In case the AubCD NPs are attached to the surface of the Au film, plasmonic coupling takes place on the surface between the Au film and the AubCD NPs, since -according to the Kretschmann measuring setup -in this case the spreading plasmons excited within the Au film are coupled with the localized plasmons (LSPR) of the AuNPs (Daly et al 2000). Figure 4 shows that AFB1 adsorbed preferentially on the βCD-modified AuNP surface, the adsorption capacity is ~30% more than on βCD-(SH) 2 surface, i.e.…”

“…This direct method thus is suitable for determination of AFB1 in important alimentary target compounds by functionalized AuNPs. An additional advantage is that no additional reagents are needed for the analysis as compared to previous studies (Daly et al 2000;Dunne et al 2005;Moon et al 2012). …”