Novel Electrochemical Sensor Based on PDA/MXene/MWCNTs/NiCo2O4 Nanocomposites for Rapid, Sensitive, and Selective Detection of Aflatoxin B1

This work established a novel nucleic acid aptamer sensor for the sensitive and selective detection of AFB1 (Aflatoxin B1), which has important implication for food safety. In a word, we synthesized MXene/MWCNTs/NiCo 2 O 4 composite nanomaterials to improve the sensitivity of the aptamer sensor. The surface of the composite nanomaterials was modified with PDA (poly dopamine) in order to immobilize the NH 2 -cDNA-aptamer complex on the electrode surface by the Schiff base reaction. Characterization of MXene/MWCNTs/NiCo 2 O 4 nanocomposites was carried by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Meanwhile, 4-carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical (TEMPO-COOH) was used as an electrochemical signal to detect AFB1. Under optimal conditions, the electrochemical DPV signal decreased with increasing AFB1 concentration, ranging from 2.5 to 200 ng/mL, and the lowest limit of detection (LOD) at 1.890 ng/mL (S/N = 3). In addition, the ensemble sensor showed great reproducibility, stability, and selectivity, which has been successfully applied to the determination of AFB1 in maize flour and maize residue samples with recoveries in the 92.2 ~ 109.8% range. Compared to other detection methods for AFB1, this approach afforded comparable detection limits and detection ranges, in reduced analysis time (within 5 min). Thus, a time-saving, sensitive, and selective approach was achieved for the rapid determination of AFB1 in food.