Disposable electrochemical microfluidic device for ultrasensitive detection of egg allergen in wine samples

Food allergies have been increasing all over the world. Egg is an important component in the food industries and the second most common cause of food allergy, shortly after milk. In the wine industry, egg white is applied as a fining agent for tannin removal. In this study, a sandwich-based immunoassay for ultrasensitive detection of ovalbumin (OVA) in wine samples was developed. The assay involves the use of magnetic beads (MBs) decorated with a polyclonal anti-OVA antibody (Ab₂) and horseradish peroxidase (HRP), used as a label for the quantification in a disposable electrochemical microfluidic device (DEμD) here developed. The Ab₂-MB-HRP prepared was applied to capture, separate, and pre-concentrate OVA from wine samples. In the DEμD, OVA was immune-magnetically captured (OVA-Ab2-MB-HRP), producing a sandwich structure (GO-Ab₁-OVA-Ab₂-MB-HRP) on the electrodes surface. This arrangement results in an ultrasensitive device, achieving the ultralow limit of detection of 0.2 fg mL⁻¹ OVA. The proposed method was successfully applied for OVA determination in samples of white and red wines showing results with excellent agreement with results obtained by enzyme-linked immunosorbent assay (ELISA). Finally, the magneto-immunoassay strategy developed in this study can be easily adapted for fast and simple detection of other proteins as allergens in foods and drinks, as well as, multiplex detection of allergens.