Sensitive detection and quantification of gliadin contamination in gluten-free food with immunomagnetic beads based liposomal fluorescence immunoassay

•Immunomagnetic beads are used for specifically isolating gliadin from food.•Immunoliposomal nanovesicles are used for instantly amplifying the assay signal.•Detection limit of this assay was lower than those of commercial ELISA kits.•This magnetic bead detection platform is suitable for a high-throughput screening.•Results of this assay are comparable to those of an AOAC ELISA kit in testing food.

Gliadin from wheat is a common food allergen that can induce baker’s asthma, wheat-dependent exercise-induced anaphylaxis, atopic dermatitis, and celiac disease. This gliadin assay focuses on rapidly screen and check for gluten contamination in raw materials and in the gluten-free food production process, not only for wheat-sensitive patients but also for the industries producing gluten-free foodstuffs. The developed assay incorporates the use of anti-gliadin antibody-conjugated immunomagnetic beads (IMBs) to capture the gliadin in samples and fluorescent dyes-loaded immunoliposomal nanovesicles (IMLNs) to produce and enhance the detection signal. Hence, a sandwich complex is formed as “IMBs–gliadin–IMLNs”. Experimental results indicate that this detection platform exhibits good sensitivity for gliadin with a detection limit as low as 0.6 μg mL−1 of gliadin; as the polyclonal antibody showed slight cross-reactions with barley and rye. Excellent recovery rates were found ranging from 83.5 to 102.6% as testing the spiked samples. Moreover, the CV (%) of intra- and inter-assay of this developed assay are 4.8–10.6% and 3.5–9.9%, respectively. Based on a parallel analysis of twenty food samples, the results of this developed assay provide a good consistency with those of an AOAC-approved ELISA kit without any false-negative results. The proposed assay method is thus a highly promising alternative method for detecting the contamination of gliadin in the food industry.

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