Electrochemical Immunosensor Made with Zein‐based Nanofibers for On‐site Detection of Aflatoxin B1

Abstract

A disposable electrochemical immunosensor for on-site detection of aflatoxin B1(AFB1), one of the most toxic mycotoxins in agri-food products, was fabricated through a low-cost cut-printing method and then modified with zein/polypyrrole(PPy) electrospun nanofibers onto which anti-AFB1 monoclonal antibodies were immobilized covalently. Fabrication was possible with an innovative and simple approach to adsorb nanofibers onto the working electrode during electrospinning. Electrochemi-cal impedance spectroscopy was employed as the principle of detection, and the data collected with a portable potentiostat were treated with information visualization techniques. The nanostructured immunosensor showed a high sensitivity for AFB1 with a linear detection range from 0.25 to 10 ng mL À 1 and a theoretical limit of detection of 0.092 ng mL À 1 , which is adequate to detect AFB1 in food, according to regulatory agencies.

Nanoarchitectonic E-Tongue of Electrospun Zein/Curcumin Carbon Dots for Detecting Staphylococcus aureus in Milk

“…The crystalline nature of cCDOT is revealed in the high-resolution TEM image in Figure 1 B with an interlattice distance of 0.27 nm, which corresponds to the diffraction planes (102) of the sp 2 graphitic carbon structure. 30 , 31 The UV–vis absorption spectrum in Figure 1 C for cCDOTs features bands at 275 nm assigned to π → π* transition of C=C (sp2 aromatic domains) and at 340 nm due to n → π* transition of C=O and C–O n → π* transition of C=O and C–O. 31 The maximum emission for these cCDOTs occurs at 460 nm under an excitation wavelength of 340 nm in Figure 1 D .…”

“… 30 , 31 The UV–vis absorption spectrum in Figure 1 C for cCDOTs features bands at 275 nm assigned to π → π* transition of C=C (sp2 aromatic domains) and at 340 nm due to n → π* transition of C=O and C–O n → π* transition of C=O and C–O. 31 The maximum emission for these cCDOTs occurs at 460 nm under an excitation wavelength of 340 nm in Figure 1 D .…”

“…Disposable electrodes were prepared with a simple, low-cost cut-printing method as described in ref ( 31 ). A conductive ink made of graphite and carbon black powders (90/10 w/w) (Synth, Brazil) suspended in shellac (Acrilex, Brazil) in a proportion of 30% (w/w) was homogeneously deposited onto the adhesive paper and then dried in an air-circulating oven for 1 h at 40 °C.A mask with electrodes, with 12.9 mm 2 , containing 1 pair of fingers (spaced by 1.6 mm), was cut from the conductive sheets using a cut printer (Silhouette, model 3, Moema/SP, Brazil) (see Figure S1 in the Supporting Information).…”

“…Electrospinning was performed for 10 min at a working distance of 8 cm, applied voltage of 22 kV at 25 ± 3 °C, and relative humidity of 30%. Fibers were directly electrospun over the electrode partially covered with aluminum foil and attached to a stainless-steel drum collector, according to Dos Santos et al 31 The modified electrodes were removed from the aluminum foil and stored in a desiccator before further use.…”

An Electrochemical Immunosensor Based on Chitosan–Graphene Nanosheets for Aflatoxin B1 Detection in Corn

“…When the immunosensor was incubated with AFB1 (15 ng/mL), a clear reduction in peak current was detected. The EIS was also a powerful tool for characterizing the step-by-step manufacturing process of the electrode [30]. The electron transfer resistance ( CT R ) was analyzed by fitting the diameter of the semicircle using the Randles equivalent circuit (inset in Figure 4b).…”