Rapid and label-free detection of egg allergen traces in wines by surface plasmon resonance biosensor

The development of a surface plasmon resonance (SPR)-based biosensor tailored to the fast detection of egg-related fining allergens in wines is herein described. Ovalbumin (OVA) was chosen as the target protein to be monitored due to its highest abundance in the egg white powder, a typical fining agent used by the winery industry to promote wine clarification. A direct assay was designed, basing on the use of polyclonal anti-OVA antibody as bio-specific receptor. With the aim of optimizing the assay conditions, different parameters able to influence the final biosensor response were carefully investigated (i.e., pH, ionic strength, and additional surfactant concentration). After the fine tuning of these parameters, the assay was tested in the direct analysis of OVA in commercial wines artificially contaminated with egg white powder at different concentration levels in order to assess the reliability of the biosensor in detecting traces of OVA in complex matrices. The devised assay allowed to trace, in a short analysis time and with a minimal sample pre-treatment required, the presence of egg allergens at the lowest concentration comprised between 0.03 and 0.2 μg/mL. Finally, the response provided by the developed biosensor was correlated with an established liquid chromatography mass spectrometry (LC-MS) method developed in our laboratories, and performances of both approaches were assessed for the fast monitoring of egg allergen contamination in fined wines.