Rapid Gluten Quantification by Aggregation-Driven Magnetophoretic Transduction Using Core–Satellite Magnetic Particles

Abstract

Reliable detection of trace amounts of gluten in food products is essential to safeguard individuals affected by coeliac disease and other gluten-related disorders. However, standard immunoassays such as ELISA, while highly sensitive, are time-consuming, laboratory-bound, and not easily adaptable to rapid on-site screening. In this work, we present a magnetophoretic biosensor based on core–satellite magnetic particles (CSMPs), functionalised with anti-gliadin antibodies through a photochemical immobilisation strategy integrated into a 3D-printed microfluidic mixer. Upon antigen binding, CSMPs undergo aggregation, which enhances their magnetophoretic migration under an external magnetic field, producing a quantifiable change in optical transmittance. A custom 3D-printed cuvette holder incorporating a permanent magnet enables time-resolved measurements with a portable spectrophotometer. The analytical response, obtained from transmittance monitoring in under 30 min, follows a sigmoidal dose–response curve with a limit of detection of 3 mg kg^-1, below the 20 mg kg^-1 regulatory threshold defined for gluten-free labelling. Validation with both commercial and spiked food samples demonstrated strong agreement with the reference R5 ELISA method across diverse matrices, confirming analytical robustness and applicability to real samples. Owing to its rapidity, low cost, and minimal instrumentation requirements, the proposed system represents a promising tool for preliminary gluten screening and on-site quality control in food safety monitoring.