A magnetic-separation-based homogeneous immunosensor for the detection of deoxynivalenol coupled with a nano-affinity cleaning up for LC-MS/MS confirmation

A magnetic separation-based immunosensor for deoxynivalenol assay, coupled with a nano-affinity cleaning up for instrumental confirmation, was developed. Maltose-binding protein with mimic epitope of DON was coupled to CdSe/ZnS quantum dot nanobeads for fluorescent reporter. Graphene oxide was linked with magnetic nanoparticles and protein G for immunomagnetic adsorbent. The magnetic separation of reporter could be inhibited by DON so the fluorescent remained in the solution indicates a good quantitative correlation to DON concentration. The DON separated by immune adsorbent can be cleaned up for instrumental confirmation. The optimized immunosensor showed results as follows: the linear range was in 0.3–3000 ng mL−1. The limits of detection (S/N = 3) were 0.50, 1.0, and 3.0 ng mL−1 in different backgrounds. The recoveries for DON-spiked samples range from 78.7% to 88.5%. Both results of UPLC-MS/MS based on affinity column purification and coupled with nano-affinity cleaning up showed a good agreement with the current immunosensor.