Anna Yu. Kolosova

Lateral flow colloidal gold based immunoassay for the rapid detection of deoxynivalenol with two indicator ranges

A lateral-flow immunoassay using a colloidal gold-labelled monoclonal antibody was developed for the rapid detection of deoxynivalenol (DON). Different parameters, such as the amount of immunoreagents, type of the materials, composition of the blocking solution and of the detector reagent mixture, were investigated to provide the optimum assay performance. The experimental results demonstrated that such a visual test had an indicator range rather than a cut-off value. Thus, tests for DON determination with two different indicator ranges of 250-500 and 1000-2000 microg kg(-1) were designed. The method allowed detection of DON at low and high concentration levels, which could be useful for research and practical purposes. The assay applied to spiked wheat and pig feed samples demonstrated accurate and reproducible results. The applicability of the developed lateral-flow test was also confirmed under real field conditions. The test strips prepared in Belgium were sent to Mexico, where they were used for the screening of DON contamination in different bread wheat entries from Fusarium Head Blight inoculated plots. The results were compared with those obtained by ELISA and LC-MS/MS. A poor correlation between ELISA and LC-MS/MS was observed. Visual results of the dipstick tests were in a good agreement with the results of the LC-MS/MS method. Coupled with a simple and fast sample preparation, this qualitative one-step test based on the visual evaluation of results did not require any equipment. Results could be obtained within 10 min. The described assay format can be used as a simple, rapid, cost-effective and robust on-site screening tool for mycotoxin contamination in different agricultural commodities.

Molecular and cellular effects of food contaminants and secondary plant components and their plausible interactions at the intestinal level

The intestinal mucosa is not simply a barrier allowing entry of compounds such as nutrients or chemicals, and restricting that of others. Intestinal cells and activities perform selective absorption, biotransformations and efflux back to the lumen. Furthermore, food substances affect both bioavailability and intestinal function. Some are able to act as transcriptional regulators and enzyme modulators. This review points out plausible interactions between food contaminants and/or natural constituents at molecular and cellular levels and focuses on the effects of classical (pesticides and veterinary drugs), environmental (heavy metals, PCBs, dioxins, etc.) and food processing generated (PAHs, heterocyclic amines, etc.) contaminants on absorption, metabolism and efflux. Special attention is given to secondary metabolites of molds (mycotoxins) and plants (polyphenols). Molecular targets are briefly described as well as regulation mechanisms. Where possible, data referred to deal with human intestinal functions in vivo, and with in vitro studies on human intestinal Caco-2 cells; however, since data related to the intestine are rather scarce, effects on molecular targets in liver are also considered. This review also points out the urgent need for fully validated high throughput in vitro tools to screen combinations of substances, at realistic intestinal concentrations. A higher priority could then be given to combinations of nutrients, xenobiotics and food contaminants, with hazardous or beneficial impacts on human health.

Fluorescence polarisation immunoassays for strobilurin fungicides kresoxim-methyl, trifloxystrobin and picoxystrobin

Fluorescence polarisation immunoassays (FPIAs) based on monoclonal antibodies for detection of three strobilurin fungicides - kresoxim-methyl (KM), trifloxystrobin (TF) and picoxystrobin (PC), were developed and optimised. Fluorescein-labelled derivatives of target antigens (tracers) were synthesised and purified by thin-layer chromatography. Influence of tracer structures on the assay parameters was investigated. For KM and TF, the best assay performance was achieved with the homologous pairs of reagents. For the PC assay, the heterologous tracer, i.e. fluorescein-labelled derivative of TF, was used. The developed FPIAs were applied to the determination of KM, TF and PC in red wine. Most optimal sample preparation was achieved with cross-linked poly(vinylpyrrolidone) as a sorbent. This clean-up is simple, rapid and allows determination of all three strobilurin fungicides in one sample. Detection limits of the developed FPIAs in red wine were 28, 6 and 5ng/mL for KM, TF and PC, respectively. Recovery in spiked samples averaged between 80% and 104%. Intra- and inter-assay coefficients of variance were less than 12%. The developed FPIA methods can be applied to screening of wine samples for KM, TF and PC residues without complicated cleanup.