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. 2024 Feb 13;9(8):8754-8762.
doi: 10.1021/acsomega.3c04619. eCollection 2024 Feb 27.

Nafion-Immobilized Functionalized MWCNT-based Electrochemical Immunosensor for Aflatoxin B1 Detection

Kai Deng  1   2 , Yining Zhang  1   2 , Hang Xiao  1 , Yujiao Hou  3 , Qingbin Xu  3 , Ying Li  3 , Weijun Kong  1   2 , Li Ma  1
Affiliations

Nafion-Immobilized Functionalized MWCNT-based Electrochemical Immunosensor for Aflatoxin B1 Detection

Kai Deng et al. ACS Omega. .

Abstract

The ubiquitous aflatoxin B1 (AFB1) contamination in foods and other complex matrices has brought great challenges for onsite monitoring. In this study, an ultrasensitive Nafion-immobilized functionalized multiwalled carbon nanotube (MWCNT)-based electrochemical (EC) immunosensor was developed for trace AFB1 detection. The introduced Nafion film could steadily stabilize functionalized MWCNTs with uniform distribution and tiling on the surface of a Au electrode. Functionalized MWCNTs with a large specific surface area, numerous active sites to couple with abundant anti-AFB1 monoclonal antibodies (mAbs), and high conductivity served as the signal amplifier for remarkably enhancing the sensing performance of the immunosensor. In the presence of AFB1, it was specifically captured by mAbs to reduce the amplified current signals, which were recorded by differential pulse voltammetry for the accurate quantitation of AFB1. Because of the synergistic effects of Nafion on the stabilization of functionalized MWCNTs as signal enhancers, the developed EC immunosensor exhibited an extremely high selectivity, excellent sensitivity with a limit of detection as low as 0.021 ng/mL, and a wide dynamic range of 0.05-100 ng/mL, besides fascinating merits of easy construction, low cost, good stability in 7 days, and good reusability. The anti-interference ability of the immunosensor was verified against three other mycotoxins, and the practicability and accuracy were confirmed by measuring AFB1 in fortified malt, lotus seed, and hirudo samples with a satisfactory recovery of 92.08-104.62%. This novel immunosensing platform could be extended to detect more mycotoxins in complex matrices to ensure food safety.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Scheme 1
Scheme 1. Illustration of a Highly Sensitive Functionalized MWCNT-Based EC Immunosensor for AFB1 Detection
Figure 1
Figure 1
(A) SEM image and (B) FTIR spectrum of the functionalized MWCNTs.
Figure 2
Figure 2
(A) DPV and (B) CV curves of the (a) bare Au electrode, (b) Au/MWCNTs/Nafion, (c) Au/MWCNTs/Nafion/EDC-NHS, (d) Au/MWCNTs/Nafion/EDC-NHS/mAbs, (e) Au/MWCNTs/Nafion/EDC-NHS/mAbs/BSA, and (f) Au/MWCNTs/Nafion/EDC-NHS/mAbs/BSA/AFB1 Ag in 5 mM K3[Fe(CN)6] solution.
Figure 3
Figure 3
Optimization of the fabrication conditions for the EC immunosensor under different (A) concentrations of functionalized MWCNTs, (B) concentrations of Nafion solution, (C) proportions of EDC and NHS, (D) incubation times of EDC/NHS, (E) activation temperatures of EDC/NHS, (F) concentrations of anti-AFB1 mAbs, (G) incubation times of anti-AFB1 mAbs, (H) incubation temperatures of anti-AFB1 mAbs, (I) incubation times of AFB1, and (J) incubation temperatures of AFB1.
Figure 4
Figure 4
(A) DPV peak current for different concentrations (0–100 ng/mL) of AFB1, and (B) the calibration curve between ΔI and the logarithm of AFB1 concentration by using the developed EC immunosensor (n = 3).
Figure 5
Figure 5
Change in DPV current intensities of the as-prepared immunosensors with the addition of the blank solution (1 × PBS, pH 7.4), 1 ng/mL AFB1, and 100 ng/mL OTA, ZEN, and DON in 1 × PBS solution (pH 7.4).
Figure 6
Figure 6
Change in DPV current intensities of the developed immunosensor in a 1 × PBS (pH 7.4) solution at 4 °C.
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