Developing a Ni-grafted magnetic nanoparticle for direct CotA capture in rapid detoxification of aflatoxin B1

Aflatoxin B1 (AFB1) exposure often causes serious food safety problems and illnesses in humans and animals, even at extremely low content. Therefore, effective degradation of AFB1 is vitally significant. Biodegradation by enzymes is an effective method to eliminate hazardous toxins, but the degradation efficiency and cost of the enzyme limit its wide application. In this work, we found that CotA derived from Bacillus subtilis can rapidly degrade AFB1 into small molecules with low toxicity. Molecular docking analysis was used to evaluate the feasibility of rapid degradation of AFB1 by CotA, and the UPLC-Q-TOF-MS was used to deduce the degradation products and pathways. Two biotransformation pathways were proposed based on the structures of these degradation products. Inspired by commercial Ni-NTA purification media, Ni-grafted magnetic nanoparticles (PNMP) were designed to capture CotA from cell-lysis buffer onto the PNMP surface, enabling direct immobilization of CotA to form PNMP@CotA. The PNMP@CotA exhibits higher activity, good tolerance to temperature and pH than free CotA. Furthermore, in vitro and in vivo experiments revealed a significant reduction in the toxicity of AFB1 degradation products.