First biosensing platform for detecting traces of almonds in processed foods by electrochemical determination of the allergenic protein Pru du 6

A novel electrochemical bio-platform for Pru du 6 determination, one of the most abundant and allergenic almond proteins, was developed to detect traces of almonds in processed foods. The bio-platform combines the application of a sandwich immunoassay on the surface of magnetic beads using specific antibodies unmodified or conjugated to horseradish peroxidase as capture and detection antibodies. The resulting magnetic bioconjugates are trapped on the surface of disposable carbon electrodes, and amperometry in the presence of hydrogen peroxide and hydroquinone is employed to measure the change in the cathodic current, which is proportional to Pru du 6 concentrations. The developed bio-platform exhibited good selectivity and sensitivity, offering a detection limit of 0.12 ng mL−1 of Pru du 6. It could determine Pru du 6 in raw dough and baked cookies incurred with 0.2 µg g−1 of almond protein with acceptable precision, providing results comparable to those obtained using an ELISA technique.