Fe3O4 @polydopamine-based microchannel resistance immunosensor for detecting deoxynivalenol in wheat samples

Food security problems caused by deoxynivalenol in grains have aroused widespread concern. Rapid analysis of deoxynivalenol still suffers from complex operation, low sensitivity, and insufficient accuracy. Herein, the Fe3O4 @polydopamine (PDA) nanoparticle with a core-shell structure was synthesized, which could conveniently conjugate the antibody of deoxynivalenol, thus forming a novel immunomagnetic separation carrier Fe3O4 @PDA-antibody for the specific enrichment of the target. Furthermore, the Fe3O4 @PDA-antibody nano-recognizer could act as the elicitor to activate the aggregation of complete antigen (BSA-deoxynivalenol) func-tionalized polystyrene (PS) beads through the antigen-antibody reaction. The aggregated Fe3O4 @PDA-antibody-antigen-PS immunocomplex was driven into the microchannel by the electroosmotic flow, inducing a remarkable change in current due to the blocking effect, which was related to the amount of deoxynivalenol. In this approach, Fe3O4 @PDA-antibody nanoparticles integrated extraction, immuno-reaction, and detection effec-tively, and the microchannel resistance sensor (MCRS) could immediately monitor the change in the current. The whole process could be completed within 1 h, which improved the efficiency and decreased the interference. This Fe3O4 @PDA-antibody-mediated MCRS was developed for the ultrasensitive detection of deoxynivalenol with a linear range of 0.05 -1000 ng/mL, and the limit of detection (LOD) was 20.7 pg/mL, which was a 21-fold enhancement compared with the enzyme-linked immunosorbent assay, providing a tool for hazardous target analysis.