A surface plasmon resonance sensor for the detection of deoxynivalenol using a molecularly imprinted polymer

Abstract

The aim of the present work was to investigate the feasibility of applying the molecular imprinting polymer technique to the detection of the mycotoxin deoxynivalenol (DON) using a surface plasmon resonance (SPR) transducer. A molecularly imprinted polypyrrole (MIPPy) film was prepared via electropolymerization of pyrrole onto a bare Au chip in the presence of a template DON molecule. Atomic force microscope SPR analysis showed that the MIPPy film was deposited homogeneously on the Au surface, with a thickness of 5 nm. The MIPPy-SPR sensor exhibited a linear response for the detection of DON in the range of 0.1-100 ng/mL (R2 = 0.988). The selectivity efficiency of the MIPPy film for DON and its acetylated analogs 3-ADON and 15-ADON was 100, 19, and 44%, respectively. The limit of detection for DON with the MIPPy-SPR for a standard solution was estimated at >1 ng/mL. These results suggest that the combination of SPR sensing with a MIPPy film as a synthetic receptor can be used to detect DON.

Keywords: deoxynivalenol; molecular imprinting polymer; polypyrrole; surface plasmon resonance; synthetic receptor.

Figure 1.

SPR spectra (a) and thickness change (b) during the formation of the DON–MIPPy film according to the charge applied at 900 mV on bare Au. (a) Resonance angle curve of the dried films measured in air. (b) The left-side Y-axis (▴) represents the difference of the resonance angle of the MIPPy film (θ) and bare (θ_bare) obtained from Figure 1(a), and the right-side Y-axis (•) represents the film thickness, as assessed using AFM.

Figure 2.

AFM images of surface morphology changes before (a) and after (b) the formation of the DON–MIPPy film. (a) is the surface image of the bare Au chip used for SPR measurements and (b) is the image of the DON–MIPPy film (1 mC; 900 mV) formed on the bare Au chip, and (c) is the image (2D, 3D and line profile) scanned on the border line between Au and MIPPy film.

Figure 3.

Reaction sensorgram of the DON–MIPPy (▴), DON–antibody (○), and non-MIPPy (▪) films (used as receptors) formed on SPR bare Au chips using the DON solution (100 ng/mL). The SPR angle shift represents the difference between the angle after injection of the DON solution and the angle of the running solution.

Figure 4.

Resonance angle shift of DON–MIPPy chips according to varying concentrations of the DON solution. For DON measurement, at least, three different replications were done.

Figure 5.

Selectivity of DON–MIPPy chips regarding several structurally similar DON analogs. The SPR angle shift represents the difference in resonance angle before and after the addition of 10 ng/mL of DON or its analogs onto the DON–MIPPy chip.