Optimization of a lateral flow immunoassay for the ultrasensitive detection of aflatoxin M1 in milk

A high sensitive immunoassay-based lateral flow device for semi-quantitatively determine aflatoxin M1 (AFM1) in milk was developed. Investigation and optimization of the competitor design and of the gold-labelling strategy allowed the attainment of the ultra-sensitive assessment of AFM1 contamination at nanograms per litre level (LOD 20 ng L−1, IC50 99 ng L−1), as requested by European regulations. A one order of magnitude detectability enhancement in comparison to previously reported gold colloid immunochromatographic assays for this toxin was obtained.Direct detection of the target toxin in milk could be obtained by acquiring images of the strips and correlating intensities of the coloured lines with analyte concentrations. The one-step assay can be completed in 17 min, including a very simple and rapid sample preparation, which allowed the application of the assay to milk samples which differ in fat and protein contents. Although imprecise (mean RSD about 30%), the method proved to be accurate and sensitive enough to allow the correct attribution of sample as compliant or non-compliant according to EU legislation in force. Agreeing results to those of a reference ELISA were obtained on 40 milk samples by matrix-matched calibration in pasteurized milk.

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► The development of a high sensitive lateral flow immunoassay is described.
► The developed assay allowed aflatoxin M1 detection in milk at level required by EU regulations.
► Article describes advances in lateral flow technology towards high sensitivity.
► A simple and rapid sample pre-treatment was proposed to overthrow matrix interference.