Seafood product safety: A hybrid graphene/gold-based electrochemical immunosensor for fish allergen analysis

Seafood product labels with accurate allergen contents can avoid and/or minimize allergic reactions. Therefore, an electrochemical immunosensor for the analysis of β-parvalbumin (β-PV, a major fish allergen) was developed. Screen-printed carbon electrodes were nanostructured with reduced graphene oxide and gold nanoparticles. The platform was characterized by scanning electron microscopy and elemental analysis. In a sandwich-type assay (∼75 min), the antigen-antibody interaction was detected by chronoamperometry using horseradish peroxidase and TMB-H2O2. A linear range of 25-3000 ng/mL, a sensitivity of 2.99 µA.mL/ng, and a limit of detection of 9.9 ng/mL (corresponding to 0.40 ng in the analysed aliquot) were obtained. The selectivity and possible interferences were assessed by analysing several other food allergens and a marine toxin. The sensor was applied to the analysis of 17 commercial foods and the effect of culinary processing (e.g., grilled, canned, smoked) on the β-PV concentration was assessed. Traces of β-PV were successfully quantified and ELISA was used to assess the results.

Detection of fish allergen by droplet digital PCR

Fish is one of fourteen allergens that must be highlighted on the label within the ingredients list. The European regulation is very restrictive to allergens with zero tolerance. Therefore, it is important to establish sensitive and specific methods for detecting fish allergen. Applicability to detect and quantify fish allergen by droplet digital polymerase chain reaction (ddPCR) has been evaluated in this work. Genomic DNA of three species belonging to the most common fish families were analyzed. PCR primers were designed to amplify a 166 bp region of the 18S rRNA gene. Comparative studies were performed to establish the optimal primer and probe concentrations. Annealing temperature was determined by using thermal gradient. The results have shown good applicability of the optimized 18S rRNA gene-method to detect and quantify small amounts of the target in samples analyzed. However, validation studies are needed in order to apply ddPCR technology for routine allergens analysis.