Applying hollow octahedron PtNPs/Pd-CuO nanozyme and highly conductive AuPtNPs/Ni-Co NCs to colorimetric -electrochemical dual-mode aptasensor for AFB1 detection.

BACKGROUND

Aflatoxin B1 (AFB1) is a secondary metabolite produced by Aspergillus flavus and Aspergillus parasiticus. This toxin is highly carcinogenic and toxic, posing a serious threat to human and animal health. AFB1 primarily enters the human body through contaminated food, particularly peanuts, corn, nuts, and wheat. These foods are easily contaminated with AFB1 during planting, harvesting, storage, and processing. Therefore, the establishment of an accurate and sensitive method for the detection of AFB1 is essential to safeguard food safety and human health.

RESULTS

This study applied catalytic hairpin assembly (CHA), hybridization chain reaction (HCR), hollow octahedron PtNPs/Pd-CuO bifunctional nanozyme, and AuPtNPs/Ni-Co NCs to develop a colorimetric-electrochemical dual-mode aptasensor for AFB1 detection. Here, Pd-CuO corner-etched octahedra with cavities and oxygen vacancy defects were first designed, followed by the synthesis of PtNPs/Pd-CuO through the loading of PtNPs to enhance the peroxidase-like activity of Pd-CuO. PtNPs/Pd-CuO effectively catalyzed the generation of blue oxidation products from 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (HO). It also enhances the redox reaction of methylene blue (MB) at the electrode and improves the electrochemical signal. AuPtNPs/Ni-Co NCs possess a large specific surface area and excellent conductivity, enhanced the redox signal of MB. Additionally, the aptasensor combined the enzyme-free amplification strategies of CHA and HCR to improve sensitivity. The aptasensor reached limit of detection (LOD) 0.76 pg/mL in electrochemical mode and 0.49 pg/mL in colorimetric mode.

SIGNIFICANCE

The designed colorimetric-electrochemical dual-mode aptasensor exhibits high selectivity, specificity, stability, and reliability. The dual-mode aptasensor had been successfully applied to the spiked analysis of edible oils, peanuts, and cornmeal, demonstrating excellent recovery rates. Therefore, the dual-mode aptasensor had a wide application prospect in the field of quality supervision and food safety.