Magnetophoretic Biosensor for the Detection of Deoxynivalenol in Food Safety Applications

This study presents an innovative biosensing technique based on the magnetophoretic migration of core-shell Fe₃O₄@Au nanoparticles functionalized with anti-DON IgG for the detection of the mycotoxin deoxynivaenol (DON). Magnetophoresis describes the movement of magnetic particles under an external magnetic field, where migration velocity is influenced by particle size and aggregation state. The detection strategy is based on the analyte-induced aggregation of nanoparticles: the presence of DON triggers the formation of aggregates whose size and number increase proportionally with DON concentration. These larger aggregates exhibit higher magnetophoretic mobility under a magnetic field, thus enabling quantification of DON through their accelerated migration toward the magnetic poles. Measurements were conducted using a specially designed 3D-printed cuvette holder with four magnets, to monitor transmittance variation over 1 hour after a 30-minute pre-incubation of the sample with the functionalized nanoparticles. The sensing parameter, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i>₀ (inflection point of the logistic fit of transmittance kinetics at 530 nm), was used to correlate migration speed with DON concentration. The sensor achieved a detection limit of 0.5 ppm, exceeding regulatory thresholds for many foods. These results highlight the potential of magnetophoretic biosensing for rapid detection of DON, offering an alternative to conventional techniques.