Spectrometer-free plasmonic biosensor for rapid detection of egg allergen ovomucoid

Food allergies are immune-mediated disorders triggered by specific food proteins, with symptoms ranging from mild to severe. Prevalence is increasing globally, particularly in children, prompting regulatory measures such as allergen labeling. However, accidental exposure remains a concern, especially in processed foods. Although biosensors offer promising on-site detection capabilities, their range remains limited. Ovomucoid (OVM), the dominant and highly antigenic egg allergen, is underrepresented in biosensing studies despite its clinical significance, highlighting the need for targeted development.

We developed a spectrometer-free, colorimetric plasmonic biosensor for the direct detection of ovomucoid (OVM), the primary allergen in egg allergy. The sensor employs silver nanodome arrays that exhibit plasmonic color shifts upon target binding, quantified by changes in color space coordinates. A direct immunoassay enabled the detection of OVM within a concentration range of several to several tens of μg/mL, which corresponds to levels known to induce allergic reactions. The detection limit was determined to be 0.024 μg/mL. High selectivity for OVM was confirmed, with no significant response to non-target proteins. Additionally, the sensor produced clear signals from egg white powder, demonstrating its applicability to real food samples. Finally, a proof-of-concept demonstration of OVM detection in a food matrix was achieved.

This study introduces a compact, spectrometer-free plasmonic biosensor integrating metasurfaces, antifouling chemistry, and simple imaging for sensitive, label-free detection of food allergens. Its scalability, ease of use, and compatibility with smartphone-based analysis highlight its potential for on-site applications and pave the way for self-used food allergen testing.