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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