An Immuno-Separated Assay for Ochratoxin Detection Coupled with a Nano-Affinity Cleaning-Up for LC-Confirmation

A self-supported electrochemical immunosensor based on Cu2O/CuO@AuNPs heterostructures for sensitive and selective detection of ochratoxin A in food

Accurate and rapid detection of ochratoxin A (OTA) residues in food can significantly reduce cancer risk due to their potent renal and liver toxicity. Herein, a heterojunction structure material used as enhanced antibody load labels is modified on flexible carbon paper to construct a novel self-supported electrochemical immunoassay for ultrasensitive OTA detection in foods. The heterojunction structure was constructed on Cu2O hexagonal crystal with exposed high-energy facets through galvanic exchange reaction, in which the surface of Cu2O was oxidized to CuO, and Au3+ was reduced to Au0. The Cu2O/CuO@AuNPs/anti-OTA modified electrode exhibited good sensitivity and selectivity for OTA detection due to the synergistic effect of exposed (110) crystallographic facets, the increase of active sites, the copper mixed valence that promotes redox reactions at the interface between electrode and analyte, along with the immune effect of OTA antibody to specific recognition. The OTA sensor shows a linear range spanning 0.05-200 ng mL-1 and a low detection limit of 0.2 pg mL-1, which could be further applied in corn and soybean solution with good recovery ranging from 94 % to 106 %. Moreover, the elliptical joint confidence region result shows that the OTA sensor has good accuracy.

Development of a visual immunosensing platform based on fluorescent microspheres for the rapid detection of ochratoxins in cereals

Ochratoxins (OTs, including OTA, OTB, and OTC), exhibit nephrotoxicity, carcinogenicity, teratogenicity, and immunotoxicity, contaminating wheat, maize, and rice, so endangering human health. In this study, we designed and screened haptens using computational chemistry to prepare mAb 4G11, which simultaneously recognized OTA, OTB, and OTC with high sensitivity and specificity. We developed a fluorescent microsphere immunochromatographic assay (FMIA), which could detect the total amount of OTs with a visual detection limit of 0.5 ng/mL and a quantification limit of 0.27 ng/mL. Recovery experiments ranged from 95.94 % to 106.01 % with coefficients of variation ranging from 2.74 % to 6.30 %. The results obtained from the FMIA were found to be in alignment with those obtained from liquid chromatography-tandem mass spectrometry. The FMIA reliability was further demonstrated using real samples. FMIA can serve as a valuable instrument for the surveillance of the content of OTs in cereals.

Nucleic acid aptamer based thermally oxidized porous silicon/zinc oxide microarray chip for detection of ochratoxin A in cereals

A nucleic acid aptamer based thermally oxidized porous silicon/zinc oxide microarray chip was constructed for the detection of ochratoxin A. The hybrid chains formed by aptamer and complementary chains labeled with fluorescent groups and fluorescent burst groups were used as recognition molecules, and the detection of toxins was accomplished on the chip by the principle of fluorescence signal burst and recovery. The modified QuEChERS method was used for sample pretreatment and the performance of the method was evaluated. The results showed that the linear range was 0.02 ∼ 200 ng/kg with the detection limit of 0.0196 ng/kg under the optimal detection conditions. The method was applied to different cereals with the recoveries of 90.30 ∼ 111.69 %. The developed microarray chip has the advantages of being cost-effective, easy to prepare, sensitive and specific, and can provide a new method for the detection of other toxins.