Development of immunochromatographic strips for the detection of dicofol

Pesticide biosensors: trends and progresses

Pesticides, chemical substances extensively employed in agriculture to optimize crop yields, pose potential risks to human and environmental health. Consequently, regulatory frameworks are in place to restrict pesticide residue concentrations in water intended for human consumption. These regulations are implemented to safeguard consumer safety and mitigate any adverse effects on the environment and public health. Although gas chromatography- and liquid chromatography-mass spectrometry (GC-MS and LC-MS) are highly efficient techniques for pesticide quantification, their use is not suitable for real-time monitoring due to the need for sophisticated laboratory pretreatment of samples prior to analysis. Since they would enable analyte detection with selectivity and sensitivity without sample pretreatment, biosensors appear as a promising alternative. These consist of a bioreceptor allowing for specific recognition of the target and of a detection platform, which translates the biological interaction into a measurable signal. As early detection systems remain urgently needed to promptly alert and act in case of pollution, we review here the biosensors described in the literature for pesticide detection to advance their development for use in the field.

Lateral flow immunoassay based on gold nanoparticles for rapid and sensitive detection of zoxamide in grape, tomato and cucumber samples

In the study, we discovered zoxamide hapten (ZOX-hapten) by introducing a carboxyl extension chain, combined it with protein to make a complete antigen to immunize mice, and generated a monoclonal antibody (mAb) against ZOX. To identify ZOX residues in grape, tomato, and cucumber samples, we used our anti-ZOX mAb to develop a lateral flow immunoassay (LFIA) strip. In grape, tomato, and cucumber samples, the calculated detection limit of the LFIA strip in grape, tomato and cucumber samples was 3.44, 4.78 and 3.53 ng/g, respectively. Using the LFIA strip, the recovery rate from grape samples was 96.4-106.8%, and that from tomato samples was 98.4-107.5%, while the recovery from cucumber samples was 99.4-111.3%. These results showed that our LFIA strip could be expected to achieve rapid screening of ZOX residues in fruits and vegetables.

Preparing monoclonal antibodies and developing immunochromatographic assay strips for the determination of propamocarb levels

Propamocarb is a carbamate fungicide used to control Phytophthora disease. Frequent and large-scale use of propamocarb means that it poses a potential threat to the health of consumers. Monoclonal antibodies against propamocarb were prepared using a hapten of propamocarb that was generated by introducing a benzene ring and a carboxyl group into the structure of propamocarb. A lateral flow immunoassay strip was developed for the detection of propamocarb in tomato and cucumber samples using the gold nanoparticle-labeled antibody. The immunoassay strip was found to provide a visible limit of detection was 5 ng/g and the cut-off value was 250 ng/g for propamocarb in food samples. For quantitative analysis, the calculated limits of detection (LODs) of the immunoassay strip were 1.43 ng/g and 0.44 ng/g in cucumber and tomato, respectively. Using the immunoassay strip, the average recoveries ranged from 95.5 ± 5.4% to 108.8 ± 6.8%, with CVs of 3.1-6.2% for the cucumber, and the average recoveries were 95.1 ± 6.5%-111.9 ± 4.2%, with CVs ranging from 3.7% to 6.8% for tomato samples. All the results demonstrated that the immunoassay strip was suitable for the detection of propamocarb in fruits and vegetables.

Antibody Generation and Rapid Immunochromatography Using Time-Resolved Fluorescence Microspheres for Propiconazole: Fungicide Abused as Growth Regulator in Vegetable

Propiconazole (PCZ) is a fungicide popularly used to prevent and control wheat and rice bakanae disease, etc. However, it was recently found to be illegally employed as a plant regulator to induce thick stems and dark green leaves of Brassica campestris, a famous vegetable in Guangdong, South China. Due to a lack of available recognition molecules to the target analyte, it is still a big challenge to establish a rapid surveillance screening method. In this study, a novel chiral hapten was rationally designed, and an artificial immunogen was then prepared for the generation of a specific antibody against propiconazole for the first time. Using the obtained antibody, a highly sensitive time-resolved fluorescence microspheres lateral flow immunochromatographic assay (TRFMs-LFIA) was established with a visual limit of detection of 100 ng/mL and a quantitative limit of detection of 1.92 ng/mL for propiconazole. TRFMs-LFIA also exhibited good recoveries ranging from 78.6% to 110.7% with coefficients of variation below 16%. The analysis of blind real-life samples showed a good agreement with results obtained using HPLC-MS/MS. Therefore, the proposed method could be used as an ideal screening surveillance tool for the detection of propiconazole in vegetables.

Gold nanoparticle-based lateral flow immunoassay for the rapid detection of flumetralin in orange

A sensitive monoclonal antibody (mAb) against flumetralin was produced and a gold nanoparticle-based lateral flow immunoassay (LFIA) strip was developed for screening flumetralin in orange.

A gold-based immunochromatographic strip for the detection of sirolimus in human whole blood

The schematic of a colloidal gold-based immunochromatographic strip for the detection of sirolimus in human whole blood.

A fluorescent paper biosensor for the rapid and ultrasensitive detection of zearalenone in corn and wheat

Zearalenone (ZEN) is a kind of estrogen-like mycotoxin which contaminates primary crops and their products under natural conditions and becomes a serious hazard to human health. In this study, we prepared a sensitive and specific anti-ZEN monoclonal antibody (mAb) belonging to the IgG2b subclass, with a 50%-inhibitory concentration of 0.034 ng mL^-1. A lateral flow fluorescence microsphere immunochromatographic test strip (FM-ICTS) for the rapid and ultrasensitive detection of zearalenone in corn and wheat samples was developed based on this mAb. After optimizing experimental parameters, the visual limit of detection (LOD) of the strip assay in both corn and wheat samples was 2.5 ng mL^-1, and the cut-off value was 25 ng mL^-1. The LOD was calculated to be 0.68 ng mL^-1 in corn samples and 0.48 ng mL^-1 in wheat samples. Recovery experiments showed that the test results of the strip were consistent with those of ic-ELISA. As a result, this FM-ICTS assay is reliable, simple and sensitive, and can be used for rapid detection of ZEN in corn and wheat.