Magnetic three-phase single-drop microextraction for highly sensitive detection of aflatoxin B1 in agricultural product samples based on peroxidase-like spatial network structure

[Display omitted] •A spatial network structure as peroxidase-like mimic was designed.•Magnetic three-phase single-drop microextraction was used for a rapid enrichment.•Catalyzed reaction combined with microextraction enhanced the sensitivity.•Aflatoxin B1 was detected successfully in agricultural product samples. In this work, a highly sensitive method for aflatoxin B1 (AFB1) detection was developed based on a peroxidase-like spatial network structure. The specific antibody and antigen of AFB1 were coated on a histidine-modified Fe3O4 nanozyme to form the capture/detection probes. Based on the competition/affinity effect, the spatial network structure was constructed by the probes, which could be rapidly (8 s) separated by a magnetic three-phase single-drop microextraction process. In this single-drop microreactor, the network structure was applied to catalyze a colorimetric 3,3′,5,5′-tetramethylbenzidine oxidation reaction for AFB1 detection. The signal was amplified significantly due to the strong peroxidase-like ability of the spatial network structure and the enrichment effect of the microextraction. Thus, a low detection limit (0.034 pg/mL) was achieved. The matrix effect of real sample can be eliminated by the extraction approach, and the practicability of this method was proved by agricultural product samples analysis.