Preparation of size-tunable FeO magnetic nanoporous carbon composites by MOF pyrolysis regulation for magnetic resonance sensing of aflatoxin B with excellent anti-matrix effect.

Magnetic nanoporous materials represent a new emerging category of magnetic materials for construction of magnetic resonance sensors. In this study, we adopted the metal-organic framework materials, MIL-101(Fe), as the precursor to prepare series nanoporous-carbon-FeO (NPC-FeO) composites. Results showed that FeO were uniformly distributed in MIL-101(Fe) and the size of MNP was precisely tuned at different pyrolysis temperatures, conferring the optimal NPC-FeO-450 °C composite with dramatically improved T relaxivity. The NPC-FeO-450 °C composite was modified with antibodies and antigens, respectively, for detection of aflatoxin B in various food samples with complicated matrix. Range from 0.010 ng mL to 2.0 ng mL, extreme low detection limit of 5.0 pg mL, and satisfied recoveries were successfully achieved, indicating excellent anti-matrix effect. These findings offer a new dimension to engineer novel magnetic materials with improved relaxivity for simple and easy sensing of food hazards in complicated food matrix without any purification or separation procedures.