Detection of Aflatoxin B1 with a Label-Free Ellipsometry Immunosensor

Abstract

The method of spectroscopic ellipsometry in total internal reflection mode (TIRE) was utilised for detection of Aflatoxin B1. The method of TIRE with the improved data analysis was capable of detection of aflatoxin molecules in low concentrations (down to 0.04 ng/ml) using a label-free and cost-effective direct immunoassay format. TIRE study of the binding kinetics yielded a large value of the association constant in the range of 10 6 l mol −1 which is typical for highly specific immune reactions. The comparison of the experimental data for three mycotoxins studied (e.g. aflatoxin B1, T-2 mycotoxin, and zearalenone) confirmed a common mechanism of the sensitivity boost due to the aggregation of hydrophobic molecules of mycotoxins in aqueous solutions.

Purification of substances contaminated with mycotoxins using functionalyzed microparticles

“…Test experiments were carried out using the TIRE method in order to find out the concentration of ZON in the solution after the treatment. In these measurements the antibodies to ZON were electrostatically immobilized on the surface of gold via the layers of P AH and protein A following well established experimental routine described in detail earlier [7][8][9][10]. A clear solution containing the residues of ZON was collected with a micropipette after sedimentation of microparticles was injected into the measurement cell and TIRE spectra were recorded.…”

“…Detection of mycotoxins, a challenging task due to low molecular weight of these molecules, was addressed in our previous publications; the method of total reflection 978-1-4577 -0624-0/11/$26.00 ©2011 IEEE ellipsometry (TIRE) was successfully utilised for detection of T2 mycotoxin [7,8], zearalenone [9] and aflatoxin B1 [10]. The sensitivity of TIRE measurements was high enough to allow label-free detection of the above toxins in low concentrations (down to 0.1 ng/ml) in a cost-effective direct immunoassay with respective specific antibodies.…”

“…After depositing another two PSSIP AH bi-Iayers containing NaCI the polyelectrolyte shell is complete, stage (d). Immobilization of antibodies on the outer surface of particles was performed in the same way as described earlier in [7][8][9][10], i.e. by deposition of a layer of protein A and then antibodies to ZaN, stage (e).…”

“…The TIRE experimental set-up was built on the basis of J.A. Wollaam spectroscopic ellipsometer M2000V and it was described in detail earlier [7][8][9][10]. The response of TIRE biosensor was obtained by recording the spectra of two ellipsometric angles \fI and � single in a standard Tris/HCI buffer solution (pH 7.5) after completing each adsorption (or binding) steps followed by the data fitting.…”

“…The response of TIRE biosensor was obtained by recording the spectra of two ellipsometric angles \fI and � single in a standard Tris/HCI buffer solution (pH 7.5) after completing each adsorption (or binding) steps followed by the data fitting. The TIRE measurements routine and data processing procedures were described in detail previously [7][8][9][10].…”