Combining magnetic MOFs as a highly adsorbent with homogeneous chemiluminescent immunosensor for rapid and ultrasensitive determination of Ochratoxin A

Ochratoxin A (OTA) is a fungal secondary metabolite produced by certain species of Aspergillus and Penicillium, and is generally found in contaminated grains, presenting considerable risks to human and animal health. Poor stability and insufficient miniaturization of equipment are the two main shortcomings of existing optical biosensors. Herein, we proposed a novel strategy where a magnetic metal-organic framework (MMOF) was used for the pre-enrichment of OTA in complex food matrices through magnetic-solid phase extraction, followed by a competitive optical fiber-mediated homogeneous chemiluminescent immunosensor (OFCI) for specific recognition of OTA in grain samples. A homemade miniaturized portable chemiluminescent device (PCD) was designed and applied as the signal readout. The MMOF performs well on OTA adsorption and its adsorption behavior could be well-described by the pseudo-second-order and Freundlich isotherm models. Compared with other MOF materials, this magnetic UiO-66-NH2 can simply synthesize, has convenient operation, and has high performance with a superior adsorption efficiency of 94 % within 10 min. The proposed MMOF-OFCI was able to quantify OTA from 0.1 to 100 ng/mL, with the limit of detection of 0.28 ng/mL. This sensor exhibited consistent results in comparison with those obtained by the HPLC-MS on real matrices of wheat and corn, thus making it more suitable for on-site detection.