Fe-Co-Based Metal-Organic Frameworks as Peroxidase Mimics for Sensitive Colorimetric Detection and Efficient Degradation of Aflatoxin B.

Building multifunctional platforms for integrating the detection and control of hazards has great significance in food safety and environment protection. Herein, bimetallic Fe-Co-based metal-organic frameworks (Fe-Co-MOFs) peroxidase mimics are prepared and applied to develop a bifunctional platform for the synergetic sensitive detection and controllable degradation of aflatoxin B (AFB). On the one hand, Fe-Co-MOFs with excellent peroxidase-like activity are combined with target-induced catalyzed hairpin assembly (CHA) to construct a colorimetric aptasensor for the detection of AFB. Specifically, the binding of aptamer with AFB releases the prelocked Trigger to initiate the CHA cycle between hairpin H2-modified Fe-Co-MOFs and hairpin H1-tethered magnetic nanoparticles to form complexes. After magnetic separation, the colorimetric signal of the supernatant in the presence of TMB and HO is inversely proportional to the target contents. Under optimal conditions, this biosensor enables the analysis of AFB with a limit of detection of 6.44 pg/mL, and high selectivity and satisfactory recovery in real samples are obtained. On the other hand, Fe-Co-MOFs with remarkable Fenton-like catalytic degradation performance for organic contaminants are further used for the detoxification of AFB after colorimetric detection. The AFB is almost completely removed within 120 min. Overall, the introduction of CHA improves the sensing sensitivity; efficient postcolorimetric-detection degradation of AFB reduces the secondary contamination and risk to the experimental environment and operators. This strategy is expected to provide ideas for designing other multifunctional platforms to integrate the detection and degradation of various hazards.