Electrochemical magnetoimmunosensing platform for determination of the milk allergen β-lactoglobulin

A very sensitive magnetoimmunosensor for the determination of beta-lactoglobulin (beta-LG) is reported in this work. A sandwich configuration involving covalent immobilization of the capture antibody (anti beta-LG) onto activated carboxylic-modified magnetic beads (HOOC-MBs) and incubation of the modified MBs with a horseradish peroxidase labeled antibody (HRP-anti beta-LG), is used. The resulting modified MBs are captured by a magnet placed under the surface of a disposable carbon screen-printed electrode (SPCE) and the amperometric responses are measured at -0.20 V (vs. Ag pseudo-reference electrode), upon addition of hydroquinone (HQ) as electron transfer mediator and H2O2 as the enzyme substrate. The beta-LG magnetoimmunosensor exhibited a wide range of linearity (2.8-100 ng mL(-1)) and a low detection limit of 0.8 ng mL(-1) (20 pg in 25 mu L sample). The magnetoimmunosensing platform was successfully applied for the detection of beta-LG in different types of milk without any matrix effect after just a sample dilution. The results correlated properly with those provided by a commercial ELISA method offering a truthful analytical screening tool. These features make the developed methodology a promising alternative in the development of user-friendly devices for on-site determination of beta-LG in dairy products. (C) 2014 Elsevier B.V. All rights reserved.